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Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

Biological organisms face multiple requirements to survive in their environments. This article describes a design method for multiobjective optimization to construct a bioinspired robot that performs multisprings-driven fast movements by exploiting several mechanical elements, such as springs, latches, and linkages. To control the duration required for preparatory loading and unloading, it is important for this power-amplification system to design the parameters of independent springs acting in the translational and rotational directions of the joint and the inertia of the arm. In our previous study, we designed an antagonistic drive mechanism with the exoskeletal springs that realizes a motion far exceeding the muscle contraction. However, the modulus of two types of elastic elements and the arm inertia were not considered. Here, we numerically simulate and experimentally demonstrate the effects of the elastic modulus of the two types of springs acting in the translational and rotational directions of the joint and arm inertia on the duration and the maximum speed and shock absorption of the arm of the mechanism. The results reveal that the compression spring stiffness to 100 N/mm (mass: 0 kg), 1000 N/mm (0.20 kg), and 100 000 N/mm (0.40 kg) minimizes the impact duration to 0.06 s, 0.121 s, and 0.148 s. In addition, varying the compression spring stiffness from 14 to 20 N/mm maximizes the arm speed to 6.4 m/s (mass: 0 kg), 3.3 m/s (0.20 kg), and 2.9 m/s (0.40 kg). Interestingly, when the inertia was low, the arm vibrated for the modulus exceeding 0.2 N/mm, with the loading duration progressively increasing. Based on these findings, a model in the multisprings-driven mechanism was proposed.

DOI： 10.1109/tmech.2023.3347727

Scopus

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DOI： 10.1109/SII58957.2024.10417700

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Other Link： https://dblp.uni-trier.de/db/conf/sii/sii2024.html#TaharaSSNMN24

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DOI： 10.1109/SII58957.2024.10417399

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Other Link： https://dblp.uni-trier.de/db/conf/sii/sii2024.html#MommaYHIN24

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DOI： 10.1109/SII58957.2024.10417527

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Other Link： https://dblp.uni-trier.de/db/conf/sii/sii2024.html#EnomotoUNSN24

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DOI： 10.1109/ROBIO58561.2023.10354762

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Other Link： https://dblp.uni-trier.de/db/conf/robio/robio2023.html#KawanoUYN23

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DOI： 10.1109/ROBIO58561.2023.10354781

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Other Link： https://dblp.uni-trier.de/db/conf/robio/robio2023.html#UzawaHON23

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DOI： 10.1109/ROBIO58561.2023.10354779

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Other Link： https://dblp.uni-trier.de/db/conf/robio/robio2023.html#OkumaNIN23

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Because exoskeletal assistive devices are worn directly by a person, enhancing cooperation is important. However, existing assistive devices have problems in terms of their cooperation with human behaviors. This is because existing assistive devices are driven by estimating the wearer’s movement intention based on predetermined movement time and device angle information. Although these methods are expected to work as expected, in practice, it is difficult to achieve the expected behavior. Therefore, an assistance method is required to reduce such misalignment with time and misalignment between the device and wearer. Therefore, this study focused on the viscoelastic properties that generate force in response to movement and are expected to enhance coordination. In a previous study, the authors confirmed the effects of viscoelastic properties or an assistive device with variable stiffness. However, viscous characteristics during movement have not been considered. In this study, we aimed to improve the coordination by focusing on the viscous characteristics. The viscous torque outputs in response to the angular velocity are expected to be driven in response to actual human motion. In this study, the viscous torque was calculated as the product of the command viscosity coefficient and the joint angular velocity and was applied to a lower-limb exoskeleton-type assist device equipped with a magneto-viscous fluid brake and a planetary gear mechanism. In addition, a viscous command that changes the torque according to speed (proposed method), a time command that changes the output value according to the passage of time, and an angle command that changes the command value according to the angle information of the device were applied to the assist device, and surface EMG measurements and command signals were compared. The target movement was a seated movement, and the left and right vastus medialis and semimembranosus muscles were measured. More than half of the subjects showed a decrease in myopotential for five subjects for all three command methods, confirming the effectiveness of the viscous command.

DOI： 10.1186/s40648-023-00262-y

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Other Link： https://link.springer.com/article/10.1186/s40648-023-00262-y/fulltext.html

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Authorship：Last author,　Corresponding author  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/access.2023.3297147

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Authorship：Last author,　Corresponding author  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author  

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Authorship：Last author,　Corresponding author  

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/lra.2023.3264725

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

In recent years, the number of pipes that have exceeded their service life has increased. For this reason, earthworm-type robots equipped with cameras have been developed to perform regularly inspections of sewer pipes. However, inspection methods have not yet been established. This paper proposes a method for anomaly detection from images in pipes using Generative Adversarial Network (GAN). A model that combines f-AnoGAN and Lightweight GAN is used to detect anomalies by taking the difference between input images and generated images. Since the GANs are only trained with non-defective images, they are able to convert an image containing defects into one without them. Subtraction images is used to estimate the location of anomalies. Experiments were conducted using actual images of cast iron pipes to confirm the effectiveness of the proposed method. It was also validated using sewer-ml, a public dataset.

DOI： 10.1186/s40648-023-00246-y

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Other Link： https://link.springer.com/article/10.1186/s40648-023-00246-y/fulltext.html

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press Ltd.  

In a virtual reality (VR) space, wearing a head-mounted display can help with the visualization of objects; however, users cannot experience realistic tactile sensations. Recently, several force feedback devices have been developed, including wearable devices that use straight-fiber-type pneumatic muscles and magnetorheological fluids. This allows the devices to render elastic, frictional, and viscous forces during spatially unrestricted movement. Nevertheless, a problem remains in that previous devices could handle many bilateral upper limb movement tasks. Therefore, this study aims to develop a device that can handle movements that interact with both arms. Based on experiments concerning the pushing motion in a VR space, the influence of the pseudo force sense was determined to not be small. In addition, we confirmed that the force sensation presented by this system was more realistic when the robot was operated with both arms than when operated with the right arm.

DOI： 10.20965/jrm.2023.p0180

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/sii55687.2023.10039173

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/sii55687.2023.10039449

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/sii55687.2023.10039212

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.polymertesting.2022.107800

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It is estimated that 250 million visually impaired people reside worldwide, and this number is expected to increase. Even though Braille blocks and guide dogs are used to guide the visually impaired, availability of installation location and cost are some of the major issues in implementing the same. Therefore, there is a need for a device for personal guidance that does not limit the location of use. Therefore, this study focuses on force-sensing presentation using the reaction force of air jets. The proposed white cane-type force-sensing device consists of a white cane, an air pressure source, solenoid valves, and a nozzle is attached to the white cane to inject compressed air. The reaction force obtained at the time of jetting generates a moment in the hand of the user, presenting force perception. Here, as a part of an initial study of the device, the effectiveness of the directional presentation, an obstacle avoidance experiment using an ultrasonic sensor, and a demonstration experiment of guidance were conducted.

DOI： 10.1109/SII55687.2023.10039470

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/iecon49645.2022.9968757

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

In this study, we propose a method to reduce the traveling load by designing a distributed robot arrangement that considers the shape of a pipeline for a cabled in-pipe mobile robot. The objective of this study is to establish a method to reduce the friction acting on the wires of a self-propelled in-pipe mobile robot and develop a robotic system that can inspect long-distance pipes. This study contributes the purpose of this research in that it proposes a model for estimating the tension acting on the wires of a mobile robot in a pipe and describes a method for reducing the traveling load using a distributed arrangement of robots. The friction acting on the wires in the bent pipe becomes a load for the robots moving in the pipe while towing the wires. Therefore, it is difficult for these robots to inspect complex, long-distance pipelines. Furthermore, we clarified the factors that cause friction forces in long-distance pipes and modeled and quantified the friction forces acting on the wires in the pipes so that each factor could be addressed. Using this model, we propose a distributed deployment method, in which multiple mobile robots are deployed. By driving two robots separated by a distance, we confirmed that two robots could move at 2.5 mm/s in a pipeline that could not be moved by a single robot. Moreover, we proposed a method for controlling the robot according to the load acting on it and confirmed that the robot equipped with this control could inspect a narrow pipe with an inner diameter of 108 mm, where a load of approximately 340 N acted on the back end of the robot, with an efficiency that was approximately 1.7 times higher. This result has the potential to enable the configuration and control of robots, which would be difficult to achieve using conventional methods.

DOI： 10.1109/LRA.2022.3191962

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Publishing type：Research paper (scientific journal)  

In this letter, we describe simulations and experiments on the occurrence of cavitation with an instantaneous force generation mechanism based on the motion of the mantis shrimp. This study aims to strengthen the striking force of the developed mechanism by realizing the mechanism of cavitation occurrence. This letter presents a motion and cavitation model for the developed mechanism and provides the results of the simulations and experiments considering the occurrence of cavitation. In previous studies, mantis shrimp have been shown to have two consecutive impacts on a hard object with cavitation in water. However, no robot can imitate the striking mechanism of the mantis shrimp and replicate two consecutive impacts. In this study, the mechanism was designed and developed based on a mantis shrimp model. From the experiment, it was observed that the developed mechanism caused cavitation only at the point of impact, rather than during arm swing. This result suggested that the striking force was strengthened, providing insight into the striking mechanism of the mantis shrimp.

DOI： 10.1109/LRA.2022.3190614

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

Recently, force feedback devices have been developed to improve the virtual reality (VR) experiences. However, most conventional force feedback devices target the upper limbs. In addition to achieving force feedback to the upper limbs, realizing force feedback to the lower limbs will make it possible to realize an experience in the VR space, which would not be achieved by force feedback to the upper limbs alone. The authors have elucidated the perceptual characteristics of the human dropping sensation to present force feedback to the lower limbs. In this study, we develop a pair of wearable force feedback shoes that can realize the falling sensation in the VR space. The proposed device meets the required specifications for descent height and acceleration to render the falling sensation. Furthermore, we confirm the usefulness of the theoretical equation by measuring the basic characteristics of the developed device.

DOI： 10.1109/IECON49645.2022.9968554

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

In recent years, force feedback devices have been developed to improve the reality of virtual reality (VR) experiences. However, most of the general force feedback devices target the upper limbs. By realizing force feedback to the lower limbs, it is possible to realize an experience in VR space that cannot be achieved by force feedback to the upper limbs alone. Therefore, in this study, we developed a lower limb force feedback device based on a physical model of the human lower limb. The output torque of the developed device that met the target torque by the experiment was confirmed. The device was then experimented with to determine if it could reproduce an impact force similar to that of a soccer pass as an initial study. The results suggested that even a low torque of 10 Nm could reproduce a soccer pass.

DOI： 10.1109/IECON49645.2022.9968915

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

Because information transmission by force is a vector quantity with magnitude and direction, it can directly affect humans. However, most existing force feedback devices are stationary, and their movement is restricted. On the other hand, wearable force-feedback devices induce a strange feeling, as they must support the reaction force of the presented force at the body fixing part. Therefore, in this paper, we propose a posture guidance method using force feedback provided by air jets. Specifically, for table tennis movement guidance, we developed a prototype with two degrees of freedom using a table tennis racket. We also conducted a hand posture guidance experiment and confirmed that the proposed method can guide the wrist posture without disturbing the wearer's movement.

DOI： 10.1109/IECON49645.2022.9968815

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/LRA.2022.3190614

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There is an urgent requirement to solve the problem of global warming. The sea ice beneath the Arctic Ocean strongly affects the global climate. However, it has not been fully explored. The range of Autonomous Underwater Vehicles (AUV) used for under-ice exploration is limited owing to their short communication range. To solve this problem, we propose a communication relay system that uses a sea ice drilling robot. We conducted excavation and gripping experiments on actual sea ice to study the parameters and control methods required to design a sea ice drilling robot. The required specifications of excavation and propulsion units were obtained from the experimental results, and a recovery method was developed to address drilling failure.

DOI： 10.1109/IECON49645.2022.9968618

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In this paper, we describe the development of short-fiber oriented rubber and its application to elongation-type actuators. Short-fiber oriented rubber, i.e., rubber containing oriented short fibers with lengths of 3 mm, has anisotropy in the direction of fiber orientation. In a previous study, it was shown that short fiber-reinforced artificial muscles made of short-fiber oriented rubber can achieve up to 17% shrinkage. However, in that study, characteristics other than the amount of shrinkage were not measured, the basic characteristics of the developed artificial muscle were unclear, and the shrinkage ratio was smaller than that for existing straight-fiber-type artificial muscle. In the present study, we developed a new method for fabricating short-fiber oriented rubber and measured the tensile characteristics in the direction of fiber orientation and vertical to the orientation direction. Moreover, we developed an elongation-type artificial muscle from the rubber sheet and measured its elongation characteristics. Test results indicated that the fabricated rubber sheet had anisotropy. They also indicated that the anisotropy increased with the fiber concentration and that the fiber restraint acted not only in the orientation direction but also in the vertical direction. Furthermore, the developed elongation-type artificial muscle was three times more anisotropic in the ratio of axial changes to diametral changes. On the basis of these results, we expect to develop an automated production method for soft actuators.

DOI： 10.1109/IECON49645.2022.9969096

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For space rockets, a rotating mixer is used to produce solid fuel. However, mixing with the rotary mixer is subject to high shear forces that limit the equipment drive. In a previous study, the authors developed a new production method using a pneumatically driven peristaltic mixing pump that simulates the intestine and a sensing system with pressure and flow rate sensors. Solid rocket fuel was successfully produced by a small pump unit. In this study, mixing experiments of solid propellant consisting of several types of powders, including metal powder and highly viscous fluids were conducted using a pump unit with a volume size eight times larger than that used in the previous study. In this experiment, mixing was performed with the materials packed in a plastic bag to increase efficiency. This reduces the contact area between the rubber tube and the contents of the device. Because only part of the mixing process is reflected in the behavior of the device, it is difficult to see differences in the sensor values, and it is unknown whether existing methods can be applied. The results of the experiment showed that the existing sensing system could be used to confirm the differences in characteristics due to the mixing process based on the time series data of air pressure and flow rate. By using Gaussian mixture model, which is a type of clustering, the mixing state was roughly binary discrimination from the acquired sensor values. This suggests that it is possible to estimate the mixing degree in large pumps using existing systems.

DOI： 10.1109/IECON49645.2022.9968625

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/IECON49645.2022.9968391

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/LRA.2022.3191962

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/access.2022.3227068

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Language：Japanese   Publisher：THE VIRTUAL REALITY SOCIETY OF JAPAN  

Various haptic devices for application to virtual reality have been developed. Most of them have to be stationary on a desk, thus users cannot move around. To overcome this shortcoming, we propose a wearable force feedback device that uses air jet. In this paper, a prototype for hand position guidance which is able to provide force in any direction is developed, and its performance to guide the wearer’s hand is evaluated by experiments.

DOI： 10.18974/tvrsj.27.3_264

CiNii Research

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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DOI： 10.1007/978-3-031-15226-9_6

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Other Link： https://dblp.uni-trier.de/db/conf/clawar/clawar2022.html#FujikawaTTOT0K22

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1007/978-3-031-15226-9_33

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Other Link： https://dblp.uni-trier.de/db/conf/clawar/clawar2022.html#NaruseTIW022

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DOI： 10.1007/978-3-031-15226-9_50

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Other Link： https://dblp.uni-trier.de/db/conf/clawar/clawar2022.html#ObaON022

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DOI： 10.1007/978-3-031-15226-9_49

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Other Link： https://dblp.uni-trier.de/db/conf/clawar/clawar2022.html#IshiiIK022

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DOI： 10.1109/RO-MAN53752.2022.9900630

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Other Link： https://dblp.uni-trier.de/db/conf/ro-man/ro-man2022.html#ShimodaFMONN22

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/ICIT48603.2022.10002720

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.20965/jrm.2022.p0276

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI  

With the diversification of robots, modularization of robots has been attracting attention. In our previous study, we developed a robot that mimics the principle of human joint drive using a straight-fiber-type pneumatic rubber artificial muscle ("artificial muscle") and a magnetorheological fluid brake ("MR brake"). The variable viscoelastic joints have been modularized. Therefore, this paper evaluates the basic characteristics of the developed Joint Module, characterizes the variable viscoelastic joint, and compares it with existing modules. As basic characteristics, we confirmed that the Joint Module has a variable viscoelastic element by experimentally verifying the joint angle, stiffness, viscosity, and tracking performance of the generated torque to the command value. As a characteristic evaluation, we verified the change in motion and response to external disturbances due to differences in driving methods through simulations and experiments and proved the strength of the variable viscoelastic joint against external disturbances, which is a characteristic of variable viscoelastic joints. Based on the results of the basic characterization and the characterization of the variable viscoelastic drive joint, we discussed what kind of device the Joint Module is suitable to be applied to and clarified the position of the variable viscoelastic joint as an actuator system.

DOI： 10.3390/act11030089

Web of Science

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This paper describes the development of a compact pneumatic valve that can obtain a high flow rate in a periodically pneumatically driven pipe-moving robot. Plumbing facilities around the world have fallen into disrepair in recent years. Pneumatically driven mobile robots are widely used as an inspection method due to the small inner diameter and complicated shape of the pipes. Various types of robots have been studied, such as earthworm, inchworm, and spiral tube robots. However, these robots are driven by existing pneumatic valve technologies, such as needle-type and solenoid valves, which limit the use of small mobile robots. Small pneumatic valves have a low flow rate, and the entire system is complicated because multiple air pressures are controlled by multiple electrical systems. Thus, focusing on the structure and periodic motion of the ball valve, we developed a pneumatic valve that can periodically apply pressure to multiple pneumatic actuators using only rotational motion with one degree of freedom. We also applied this pneumatic valve to a wave propagation robot and discussed the theoretical running speed of the robot with this valve.

DOI： 10.1109/ACCESS.2021.3135035

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In this paper, it is proposed a grease dust cleaning mechanism using a planetary gear mechanism to remove accumulated grease in ventilation ducts.In existing research, cleaning robots have been developed to remove dust from air-conditioning ducts. The robot successfully removed dust from the ducts by rotating and scraping the brushes and using air pressure. However, no cleaning mechanism has been developed to remove the highly viscous grease that adheres to the ventilation ducts installed in restaurants. Thus, it is difficult to clean the oil and dust ducts, which are impenetrable.Therefore, in this paper, the authors propose a grease-cleaning mechanism using a planetary gear mechanism for cleaning grease from round ducts. This mechanism cleans the inside of the pipe by scrubbing off the grease from the walls by the rotation and revolution of the brush. This paper describes the selection of the cleaning mechanism, the modeling of the brush trajectory, the control method, and the evaluation experiment of the control method. The evaluation experiment of the control method confirmed the validity of the model and the fact that the brushes made contact with the entire inside of the pipe. This shows the possibility that the inside of the pipe could be efficiently cleaned by the intermittent collisions of the dispersed brushes.

DOI： 10.1109/SII52469.2022.9708739

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Other Link： https://dblp.uni-trier.de/rec/conf/sii/2022

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DOI： 10.1109/SII52469.2022.9708865

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Other Link： https://dblp.uni-trier.de/rec/conf/sii/2022

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)  

In this study, the authors comprehensively evaluated the traveling performance of a flexible pipe inspection robot (PI-RO) that can actively output both propulsion and traction forces. Household pipes must be frequently inspected for cracks and corrosion to ensure continuous provision of water and gas. As these pipes are essential for our everyday life, it is difficult to suspend their usage for long periods; hence, inspection should be conducted for short durations. In addition, inspecting entire pipelines using existing methods is challenging because the pipes are constructed over long distances and have complex structures. Therefore, we developed a flexible robot that can actively output propulsion and traction forces to inspect long-distance complex pipelines, such as household pipelines. Herein, we describe the flexible structural design of a PI-RO that inspects thin one-inch pipes (inner diameter of approximately 28 mm) typically present in household piping. We also evaluated the characteristics of each PI-RO unit. Finally, we confirmed that the PI-RO is not significantly affected by the traveling environment, such as long distances and complex small-diameter pipes, by conducting traveling experiments on small pipes (inner diameter 28 mm) and long-distance (up to approximately 11.7 m) complex pipes composed of horizontal, vertical, and 90° bend pipes.

DOI： 10.1109/ACCESS.2021.3114698

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J-GLOBAL

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We propose herein a method for estimating the mixing state of the contents of a peristaltic continuous mixing conveyor simulating the intestine, developed for mixing and conveying powders and liquids. This study serves to improve a previously proposed method for estimating the mixing state using a logistic regression model with the pressure and flow rate sensors installed in the device as inputs. Moreover, the estimation accuracy of the proposed method is better than that of the previous method. The generalizability of the proposed method is evaluated for four conditions in which the feeding order of the contents, powder, and liquid are changed. The feeding order is as follows: powder first, liquid first, and powder and liquid alternately. As a result, a highly accurate estimation of mixing is achieved under the condition wherein the powder component is in the unit adjacent to the lid, but not under the condition wherein the liquid component is fed first. It is speculated that this is because the movement of the powder component inside the device is more easily reflected by the pressure and flow rate sensors installed in the device than in the liquid component.

DOI： 10.1109/ACCESS.2021.3112614

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：Springer  

In this study, the authors started to develop a robot that can clean grease in ventilation ducts. We determined the required specifications of the robot, constructed a model of the cleaning brush, and developed grease samples. We also conducted experiments to evaluate the performance of the cleaning tools in cleaning grease with different materials, bristle shapes, and rigidity. As a result, it was found that the brush-type could scrape the grease off the cleaning surface and adsorb more grease between the bristles of the brush than the sponge-type. It was also confirmed that the contact area of the brushes affected the cleaning performance. The brush composed of nylon bristles showed the highest cleaning performance at 94%.

DOI： 10.1007/978-3-030-86294-7_31

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Other Link： https://dblp.uni-trier.de/rec/conf/clawar/2021

Authorship：Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：Springer  

The results of an excavation experiment in an actual sea area using the earth worm type seabed exploration robot are reported in this paper. The robot tested in the experiments is SEAVO II, which has been developed by the authors. Seawater-resistant processing was applied to the SEAVO II, and field experiments were conducted on the coast of Izu Oshima island. Four types of experiments were conducted: vertical excavation in sand, gravel, and water, and horizontal excavation in sand. In the vertical excavation on sand, the SEAVO II successfully excavated 490 mm, which is the same level as that of the previous studies. However, although the excavation was difficult and the excavating distance was limited to 100 mm or less for the other three conditions, the issues in each environment could be clarified.

DOI： 10.1007/978-3-030-86294-7_30

Scopus

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Other Link： https://dblp.uni-trier.de/rec/conf/clawar/2021

Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：Springer  

DOI： 10.1007/978-3-030-86294-7_13

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Other Link： https://dblp.uni-trier.de/rec/conf/clawar/2021

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In this study, we evaluate the dropping sensation for the development of a wearable lower limb force feedback device that can render both dropping and walking sensations. The developed device can render the dropping sensation at a smaller height than in reality by decelerating and stopping descent during the rendering of the drop image. Considering the user will be walking with the device, a smaller device height leads to better safety. The purpose of this study is to clarify the required specifications of the height of the vertical range of motion of the platform part, and the feasibility of the concept of rendering the dropping sensation. For this purpose, the dropping sensation for the difference in human acceleration time and human deceleration acceleration was evaluated. The results showed that the rendering of the dropping sensation required more than 0.41 s of descent at an acceleration of approximately 1377 mm/s2. Moreover, the dropping sensation and sense of reality were not impaired, even when the platform part of the foot was decelerated. This result indicates that the device can be made smaller.

DOI： 10.1109/RO-MAN50785.2021.9515498

Scopus

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/AIM46487.2021.9517503

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Other Link： https://dblp.uni-trier.de/rec/conf/aimech/2021

Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Investigation of the lunar subsurface environment is expected to lead to the elucidation of the origin of stars and the discovery of new resources. However, there are still many unknowns in this regard. In a previous study, we developed a drilling robot for lunar exploration and succeeded in drilling vertically up to 938 mm. However, control methods for the robot have not been studied in detail so far, and the grasping state of the propulsion unit during drilling has not been observed. In the study described in this paper, threshold coordination method for the current of the propulsion unit's motors is introduced to achieve effective hole grasping and propulsion. Subsequently, gripping force and penetrating force characteristics of the propulsion unit are tested to understand the grasping state of the propulsion unit during drilling based on the current value and the angle information of the motor. Finally, in-pipe propulsion and excavation experiments were conducted. From the experimental results, we concluded that the proposed control method can be used to grasp the hole with changing hole diameter and monitor the grasping state of the propulsion unit in the hole.

DOI： 10.1109/AIM46487.2021.9517536

Scopus

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/AIM46487.2021.9517474

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Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

We developed a robot generating instantaneous force inspired by the smashing mantis shrimp, and conducted dynamic analysis using the mechanistic model. We compared the performance with and without the elastic elements of the exoskeleton to examine the contribution of each spring element. Previously, we confirmed the operation of the proposed mechanism of the shrimp-inspired-system. Because the effectiveness of the mechanism has not fully been examined as an integrated system of elastic components, here we further performed the rigorous numerical simulation using the model otherwise understanding would be limited in the physical robot. From the numerical results, it was confirmed that the proposed mechanism including the spring shortened the time to strike by 0.737 times and increased the impulse at the time of strike by 1.702 times compared with the mechanism using only pneumatic artificial muscles. The results of the simulations demonstrated the interaction between the pneumatic artificial muscles and the elastic elements of the exoskeleton. Our findings can give an insight into the integrative design of the artificial muscles and elastic mechanisms by capitalizing on a design evolved in nature.

DOI： 10.1109/lra.2021.3094740

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Publishing type：Research paper (international conference proceedings)  

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In a virtual reality (VR) space, wearing a head-mounted display can help with the visualization of objects although users cannot experience realistic tactile sensations. Recently, several force feedback devices have been developed, including wearable devices that use straight-fiber-type pneumatic muscles and magnetorheological fluids. This allows the devices to render elastic, frictional, and viscous forces during spatially unrestricted movement. However, during friction and viscosity rendering, the elasticity of the artificial muscle is influenced by the elastic element of the muscle, preventing proper presentation of the force. Therefore, this study proposed a clutch mechanism to switch the force presentation of elastic elements by the contraction of artificial muscles. The mechanism was incorporated into a wearable four-degrees-of-freedom force feedback device, and its elastic, frictional, and viscous force feedback performances were quantitatively assessed via fundamental property experiments. Furthermore, a VR space was constructed to present the operator with force perceptions of virtual elastic, frictional, and viscous objects within that space, and the system's performance was qualitatively assessed. The results confirmed a reduction in the effect of elastic elements and an improvement in the presentation performance. Additionally, the use of this device in the VR space was confirmed to improve the realism of virtual objects in terms of friction and viscosity.

DOI： 10.1109/ICIT46573.2021.9453574

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Aeronautical and Space Sciences  

DOI： 10.2322/tastj.19.211

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To reduce lower back pain of workers, we developed an assist suit for lumbar support in our previous studies. This suit, called AB-Wear II, has mechanisms to aid muscle strength through the inflating power of artificial muscles and balloon actuators, and reduce compressive forces acting on the spine through leaf springs. However, due to the stiffness of the leaf spring and the soft fabric supporter fixed to the wearer's waist, the device slipped out of place during a lifting motion, causing a loss of assistive force. In this study, a new version, AB-Wear III, was developed. The leaf springs in AB-Wear III are composed of a soft material that allows them to follow a wearer's movements. The leaf spring supports the posture of the spine by applying pressure against the back, and it should also reduce the shear force that causes lower back pain. In addition, a lumbar fixation mechanism using a leaf spring wound in an arc shape near the pelvis was developed to fix the device to the body of a wearer and prevent the device from slipping. Based on the electromyography (EMG) of the erector spinae muscles during a lifting motion while wearing AB-Wear III and a questionnaire, the optimal contact position between the back and leaf spring was found to be 60% of the spine length. At the abovementioned length, EMG was reduced by 16.7% than without the device. Subjective experiments also confirmed that the wearers' endurance was improved and lower back pain was reduced using the device.

DOI： 10.1109/ICIT46573.2021.9453629

Scopus

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Aeronautical and Space Sciences  

DOI： 10.2322/tastj.19.205

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Robotics Society of Japan  

<p>In this paper, the authors described the modeling method of the instantaneous force generation mechanism inspired by the striking motion of Odontodactylus scyllarus and the evaluation of the mechanism. Animals use the contraction of living muscle as actuators to perform various movements. Some arthropods produce instantaneous movements by using the combined force of the exoskeleton spring and muscle force. Few reports deal with such an instantaneous force generation mechanism of the combined force in the numerical simulation. Our purpose of this study was to construct the instantaneous force generation mechanism by the combined force of elastic elements of the exoskeleton and pneumatic artificial muscles, inspired by the instantaneous force generation mechanism of Odontodactylus scyllarus. In the previous study, we have confirmed that the instantaneous force generation device and the possibility of generating instantaneous force by the physical model. In this paper, the authors further constructed a model of the proposed mechanism as a translational rotation system and performed a dynamic analysis by numerical simulation, confirming the effectiveness of the proposed model. </p>

DOI： 10.7210/jrsj.39.181

CiNii Research

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In this paper, the prototype of the assistive suit for lower limbs was developed. The prototype was based on an assist method with joint stiffness and antagonized angle control. The assist method comprises a system consisting of a pneumatic artificial muscle and a pull spring, which changes the joint stiffness and the antagonized angle to correspond to the movement phase and aims at coordinated motion assistance with the wearer. First, the characteristics of the developed prototype were tested. It was confirmed that the measured value of the prototype followed the target value in the relationship between torque and angle. In addition, there was hysteresis in the measured value, but it did not affect the assist. Next, the evaluation of standing-up and gait assist by measuring electromyography (EMG) of the knee extensor muscle was conducted using the prototype. In all subjects, a decrease in EMG due to the assist was confirmed. In one subject, the maximum decrease rate at the peak of the EMG was about 50% for standing-up motion and about 75% for gait motion. From the results of these assist evaluations, the effectiveness of the assist method based on the joint stiffness and antagonistic angle control using the prototype was confirmed.

DOI： 10.3390/act10010017

Scopus

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Springer  

DOI： 10.1007/978-3-030-86294-7_29

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Other Link： https://dblp.uni-trier.de/db/conf/clawar/clawar2021.html#TokoiTTWO0Y21

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.2139/ssrn.3996748

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Robotics Society of Japan  

<p>In recent years, the aging of pipelines has been severe and has caused fatal accidents. The pipe diameters are small, and the layouts are complex. Pneumatically driven mobile robots have become popular as inspection methods. Various types of robots have been studied, like earthworm-type robots, inchworm-type robots, and spiral-tube-type robots. Typically, they make periodic movements; however, they have challenges because they are driven by existing pneumatic valve technologies, which are limited to small mobile robots. Small pneumatic valves have low flow rates and limit the performance of pneumatic actuators. Therefore, we focused on the structure of the ball valve and periodic motion. Furthermore, in this paper, we developed the Compact Rotary Valve Mechanism for pneumatic mobile robots in pipe inspection, which generates periodic air pressure. </p>

DOI： 10.7210/jrsj.38.965

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In recent years, soft robots, such as those with high human affinity and those that excellently imitate the movements of natural creatures, have gained considerable attention. In soft robots, structurally flexible soft actuators need to be used, not conventional motors or hydraulic/pneumatic cylinders. Various types of soft actuators have been developed depending on the driving principle. A pneumatic rubber artificial muscle is a kind of soft actuator that acquires power through injection of a working fluid, such as air, into an elastic structure, such as rubber. In this study, the authors developed an actuator, namely, the straight-fiber-type artificial muscle, which exhibits excellent contraction characteristics. This artificial muscle consists of a rubber tube that contains reinforcing fibers arranged in the axial direction. When air pressure is applied to the rubber tube, the artificial muscle expands only in the radial direction and contracts in the axial direction due to the restraining effect of the reinforcing fiber. While this artificial muscle exhibits excellent contraction properties, it has some drawbacks. One is the difficulty in enclosing the reinforced fibers that have accumulated in the rubber tube, making this artificial muscle difficult to manufacture. In this study, we investigated short-fiber-reinforced artificial muscles that can be easily manufactured. First, a short-fiber-reinforced rubber was prepared, and anisotropy was evaluated via a tensile test. Then, the short-fiber-reinforced artificial muscles were prepared, and their contractions rates were evaluated. The results confirmed that a short-fiber-reinforced rubber can be useful for the manufacture of artificial muscles.

DOI： 10.3390/iecat2020-08526

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DOI： 10.1299/transjsme.20-00052

J-GLOBAL

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DOI： 10.20965/jrm.2020.p0863

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Welding is one of the forms of nonautomated, heavy labor used in the shipbuilding industry. In the shipbuilding process, the hull is first welded by an industrial automatic welding machine, then irregular welded part correction and welding in narrow places that machines cannot reach are performed by welding workers. Welding operators are required to weld indeterminate objects in narrow working spaces. In addition, it is difficult to perform high-quality welding because the ability to accurately trace a welding line at a constant speed requires a long training period. In this research, a welding training device that assists trainees in skill acquisition was developed. The proposed device, which comprises two magnetorheological (MR) brakes, renders a welding path and restricts welding speed. The MR brakes have a response speed comparable to that of powder brakes, have a high output-to-weight ratio, and are also considered to be suitable for use in welding training devices. A prototype and control strategy were developed, and the performance of the device in actual welding work was evaluated. Results shows that path rendering strategy is possible to present routes with an accuracy of 1 mm or better and speed control strategy can regulate the speed required for welding.

DOI： 10.1088/1361-665X/aba846

Scopus

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/RO-MAN47096.2020.9223476

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Other Link： https://dblp.uni-trier.de/db/conf/ro-man/ro-man2020.html#TanakaOONN20

Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/RO-MAN47096.2020.9223612

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Other Link： https://dblp.uni-trier.de/db/conf/ro-man/ro-man2020.html#YamadaAWFNK020

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In this paper, a mechanism for generating an impulsive force by using the distortion of an exoskeleton is described. Pneumatic artificial muscles not only have a high power to weight ratio, but also have a high affinity with the human body due to their use of air pressure. However, pneumatic artificial muscles have a slow stretch response rate due to their viscous properties. Therefore, earthworm type mobile robots and wearable assistive devices using artificial muscles move slowly and have difficulty assisting human movements. We focus on the mechanism of force generation using the distortion of the exoskeleton, similar to what is seen in the punching of a mantis or the jumping of a grasshopper, as a countermeasure against the delay in the response rate of the artificial muscle. In this study, we propose a new mechanism to generate a shooting force by incorporating an element similar to an exoskeleton spring into the antagonistic drive mechanism of an artificial muscle. We designed and developed a prototype then operated it and measured the impulsive force. It was found that the developed mechanism showed similar joint movements through muscle contraction to those of mantis shrimp and grasshoppers. Furthermore, it was shown that the time constant for the maximum strike force was 6.6 N and 63.2 % of the maximum impulsive force was 0.183 s.

DOI： 10.13180/clawar.2020.24-26.08.63

Scopus

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In the study, we propose a negative-pressure-driven soft linear actuator for the fixation part of an exoskeleton. In the study, a concept of the fixation part that is easy to wear with reliable force transmission is first proposed. Subsequently, a negative-pressure-driven soft linear actuator for the proposed fixation method is introduced and prototyped. Finally, basic characteristic experiments are conducted with a prototype. The results indicate that decreases in the pressure increase the actuator's contraction force and maximum contraction. It exhibits a large hysteresis that is approximately 50% at maximum contraction force. Increases in the width increase the contraction force. Increases in the height increase the force and rate of contraction.

DOI： 10.13180/clawar.2020.24-26.08.30

Scopus

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/AIM43001.2020.9158981

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Other Link： https://dblp.uni-trier.de/db/conf/aimech/aim2020.html#OkuiMTON20

Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/AIM43001.2020.9158954

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Other Link： https://dblp.uni-trier.de/db/conf/aimech/aim2020.html#AdachiMWHUYN20

Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/AIM43001.2020.9158861

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Other Link： https://dblp.uni-trier.de/db/conf/aimech/aim2020.html#MachidaKSYON20

Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/AIM43001.2020.9158934

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Other Link： https://dblp.uni-trier.de/db/conf/aimech/aim2020.html#ToyamaITWOYN20

Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/AIM43001.2020.9158972

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Other Link： https://dblp.uni-trier.de/db/conf/aimech/aim2020.html#SatoMIYONN20

Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2020 IEEE. A peristaltic continuous mixing conveyor that focuses on the mechanism of the intestine has been developed as a technology for the mixing and transport of a solid-liquid mixture and high viscosity fluids. The developed peristaltic continuous mixing conveyor succeeded in the mixing and transport of such mixtures in a previous study. A simple cyclic pattern is currently used as the movement pattern of the system, and the control method can be further improved. In this study, we aim to realize an intelligent mixing and generation of a conveyor pattern based on intestinal movement. The mixing state of content during activation was estimated through machine learning. The results from the time-series measurement data show that an internal mixing state in three units of the peristaltic continuous mixing conveyor was estimated.

DOI： 10.1109/RoboSoft48309.2020.9116058

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This study proposes the development of a locomotion robot using a deformable dielectric elastomer for actuation without pre-stretch. Electroactive polymers (EAPs) that are driven by electrical stimulation have recently garnered attention. Among EAPs, dielectric elastomer actuators (DEAs) are focused herein. DEAs have a structure wherein a dielectric is sandwiched between elastic electrodes. The performance of the DEA depends on the relative permittivity, Young's modulus, and the applicable voltage of the dielectric material. DEAs are usually used with pre-stretching, because of the material properties of the dielectric, which requires a large stress in the initial stage of extension, and the increase in the displacement of DEAs with the application of pre-stretch. However, because rigid frames are generally used for prestretching, there are few DEA applications that utilize their flexibility. Therefore, we focused on slide-ring materials (SRMs) as new dielectric materials. SRMs are polymer materials in which the cross-linking points move freely, and having excellent properties as dielectrics for DEA applications. Thus, pre-stretching is not required, and applications utilizing the flexibility of DEAs is possible. In previous research, a bending unit that did not require pre-stretching was manufactured by attaching non-stretchable tape to one side of the DEA using an SRM as the dielectric material. In addition, a locomotion robot with a bending unit was developed, and it was confirmed that the robot achieved locomotion because of a phase difference between the units. However, the basic characteristics of the bending unit and locomotion robot were not discussed. Therefore, in this research, we measured the frequency characteristics of the bending unit alone and demonstrated the locomotion of the robot.

DOI： 10.1117/12.2558422

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During overhead work, workers need to keep raising weights of approximately 2 to 4 kg with the muscular strength of their upper limbs, and the burden of this work is high. Therefore, we developed an assistive device, named TasKi, using a self-weighted compensation mechanism to reduce the burden on upper limbs during overhead work. It can compensate for upper limb weight using the force of a spring in various postures of the upper limbs, without a battery. In this study, to provide effective assistance to many users, we clarified the crucial assistance and parameter adjustment range of settings corresponding to physical differences. First, the assistive force value of TasKi to reduce the work burden of each user was confirmed via a subjective evaluation experiment and myoelectric potential-measurements. Next, we conducted a test survey of TasKi users and investigated the relationship between physique and the wearing feeling. According to the survey, 80% of the subjects provided favorable opinions on the assistive method used by TasKi. Finally, we had subjects of various physiques wear the device and investigated the relationship between physique and the wearing feeling with respect to shoulder joint movements. It was observed that the subjects with greater shoulder widths experienced difficulties when moving in the direction of internalexternal rotation because of the small size of TasKi. The influence on the ease of motion and perception of size was less in the direction of flexion-extension and adduction-abduction motions.

DOI： 10.20965/jrm.2020.p0138

Web of Science

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DOI： 10.1109/ACCESS.2020.2972572

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：FUJI TECHNOLOGY PRESS LTD  

Globally, lower back pain is a serious problem. For workers, it not only causes health problems but also has social and economic influences. Lower back pain could be attributed to burden on people's waists when they handle heavy objects. Ministry of Health, Labour and Welfare in Japan recommends squat lifting, a method of lifting objects with a smaller burden on waist. On the other hand, squat lifting is not commonly used because it requires deep bending of knees to lift an object, leading to a larger work load. Therefore, a leaf-spring type power assist suit for legs has been developed in order to assist squat lifting. However, if the fixing performance of a preceding machine was enhanced, a leaf spring could impede the bending of knee joints during gait motion. In the present study, we developed a power assist suit for legs using a slide mechanism. A leaf spring was chosen so as to meet a target assist torque determined by a motion analysis for lifting objects. In addition, we made a prototype machine with slide mechanism. EMG measurement of the thigh muscle during lifting actions using the prototype machine showed a decrease of up to 46%. It was also confirmed that a machine with slide mechanism could realize a more natural gait than a machine without it.

DOI： 10.20965/jrm.2020.p0209

Web of Science

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© 2020 IEEE. Powders are used in various devices, including printing presses. To prevent agglomeration, the powder in a printing press must be conveyed by a technique with low shear force and no temperature rise. The present study introduces a powder-conveyance robot based on peristaltic movements of the human intestinal tract, and evaluates it on the powder used in printing presses. The human intestinal tract is non-skeletal, soft and plays an important role as soft actuation. In our previous study, the peristaltic-motion type conveyor transported the powder at high speed (81.5g/s) without aggregation. However, the behavior of the inner tube after changing the characteristics and wavelength of the unit is unknown. This research investigates the conveyance amount and the inner-tube movement of a peristaltic-motion type conveyor unit operated at different wavelengths and operation intervals. By simultaneously mapping each parameter, we aim to increase the speed conveyance in future work.

DOI： 10.1109/SII46433.2020.9026224

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2020 IEEE. Recently, various types of soft actuators and their applications have been studied in the search for alternatives to conventional robots. In particular, pneumatic soft actuators have the advantages of a light weight and high power. One of the applications of such soft actuators is fusion with flexible structures. However, because these actuatable flexible structures consist of rubber, silicone, or flexible resin, it is difficult for them to support their own weight, owing to the effect of the square-cube law in the case of an increasing size. We have developed actuatable flexible structures. LayerCAKE is a laminated open-cell and closed-cell foam structure, where cell foam is a lightweight and flexible material that can be used to realize large actuatable flexible structures. LayerCAKE is actuated using the concept that open- and closed-cell foams contract differently when they are vacuumed. In this paper, the design of a large LayerCAKE mechanism is described and tested. A large actuatable flexible structure of size approximately 1250 mm that bends in a vertical direction was realized.

DOI： 10.1109/SII46433.2020.9026003

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2020 IEEE. Actuators known as pneumatic artificial muscles are superior for practical use because they do not require maintenance, are inexpensive, and can be assembled with a drive unit and an energy generation unit independently. However, because these actuators expand greatly in the radial direction when pressurized, one problem is that they occupy a large amount of space and consume a significant amount of flow. In this study, we propose a space-saving, constant-axis fiber-reinforced artificial muscle that does not expand and also takes advantage of the benefits of pneumatic artificial muscles. Hence, this paper reports on the driving principle of the proposed noninflatable pneumatic artificial muscle and the basic characteristics are then confirmed using a prototype.

DOI： 10.1109/SII46433.2020.9026201

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2020 IEEE. Force feedback devices are attracting attention as a way to apply virtual and augmented reality to entertainment, sports, and rehabilitation. We previously developed a force feedback device using pneumatic artificial muscle and a magneto-rheological fluid clutch. However, problems occurred, such as an increase in the weight of the device and complications in the control system. To solve these problems, a new force feedback method using an elastic spring and a magneto-rheological fluid clutch was therefore proposed. In addition, the force feedback characteristics of the force feedback method were modeled. A 1-degree-of-freedom force feedback device using the new force feedback method was also developed. The model characteristics of the force feedback for rendering the elasticity using the device were confirmed experimentally.

DOI： 10.1109/SII46433.2020.9025927

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2020 IEEE. We attempt to generate traveling waves by applying a dielectric elastomer actuator (DEA) with a sliding ring material (SRM). A normal DEA using silicon or acrylic rubber requires pre-stretching with a rigid frame to obtain a large displacement, owing to the material properties of the dielectric, which require a large stress to be applied at the initial stage of the extension. A DEA using an SRM does not need to be restricted by a rigid frame and can be expected to generate large displacements and complex motions while maintaining its flexibility. In this paper, we report the development of a traveling wave generator as an initial study. Through experiments, the developed DEA was confirmed to function as an actuator without pre-stretching. In the future, in addition to determining the optimum phase difference, frequency band, and shape of the constrained parts to increase the speed, we plan to develop a mobile robot utilizing a DEA traveling wave with a mechanism that would allow the units to overlap.

DOI： 10.1109/SII46433.2020.9026285

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© 2020 IEEE. In this paper, we describe the performance of a pneumatic artificial muscle integrally molded by a 3D printer that can mold materials with different stiffnesses.In the recent years, soft and hard materials can be integrally molded as the performances of 3D printers improve. For this reason, attention has been focused on the integral molding of actuators by using 3D printers. In this study, an artificial muscle is integrally molded by a state-of-the-art 3D printer, and the amount of contraction and contraction force generated are experimentally measured. In particular, the integrally molded artificial muscle formulated in this study is a pleated artificial muscle that does not require high material stretching performance. When the stiffness of the leaf spring material constituting the 3D printable artificial muscle is changed in a stepwise manner, the generated contraction amount and force were measured. From these measurement results, the usefulness of this actuator was confirmed by comparing the generated force with that of a pneumatic piston with the same inner diameter.

DOI： 10.1109/SII46433.2020.9026165

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Other Link： https://dblp.uni-trier.de/db/conf/sii/sii2020.html#ItoKON20

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© 2020 IEEE. In recent years, expectations for low-cost and high-frequency rocket launches for space exploration have increased. Solid fuel rockets are small, inexpensive, and easy to handle. However, in the production of solid fuel, the mixing process and the transportation process are separate batch processes, leading to an increase in maintenance costs and disposal costs. In addition, being a manual process, it is difficult to manufacture large amounts simultaneously in a safe method. The authors have developed a mixing and transportation device that simulates the movement of the intestinal tract by using an elastic duct and a low pneumatic drive. In addition, actual fuel production has been carried out in a mixing and transporting experiment using this device. The effectiveness of this device has been exhibited from the combustion test of the produced fuel. In this paper, we present a high-quality and efficient method of mixing and transporting solid propellant material. This is a mixing of solid and liquid achieved by peristaltic movement done in real-time by adjusting the mixing degree of the mixture inside the device. The degree of mixing is determined by the solid propellant's volume and viscosity change. Therefore, we first investigate whether the content volume can be detected when the rigid bodies with different volumes are inserted. Next, we focus on the change in the viscosity of the mixture that occurs during the mixing process. We also examine the viscosity of the contents when fluids having different viscosities are inserted.

DOI： 10.1109/SII46433.2020.9025893

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Other Link： https://dblp.uni-trier.de/db/conf/sii/sii2020.html#WakamatsuHAAIYH20

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© 2020 IEEE. Mineral resources have been discovered on the bottom of the ocean; to utilize them, seabed soil samples must be obtained and analyzed. This study aimed to develop a seafloor robotic explorer that can excavate and gather samples of the seafloor soil. In our previous study, we developed a drilling robot named SEAVO II that could excavate 430 mm into the sand ground underwater. However, in the present study, the target to be excavated was the rare earth mud layer. Therefore, we examined the drilling properties specific to the underwater clay ground. In addition, a drilling experiment in the clay ground was conducted using SEAVO II. The results showed that SEAVO II could successfully dri11430 mm into the clay ground underwater.

DOI： 10.1109/SII46433.2020.9026231

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Other Link： https://dblp.uni-trier.de/db/conf/sii/sii2020.html#IsakaTWTOYN20

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

This paper describes multi-segmentation of artificial muscles integrally molded by a 3D printer and simplification of post-processing. In recent years, with the improvement in performance of 3D printers, it has become possible to integrally mold flexible and hard materials. From this, attention has been focused on the integral molding of actuators that makes effective use of the complex structure of 3D printers. Most of the actuators using 3D printers use air pressure, and in consideration of the material properties, pistons using a bellows structure are common. However, the output of the piston is small because the pressure receiving area is small. Therefore, the pneumatic artificial muscle was integrally molded using the structural advantage. In this paper, we focused on the contraction length of the artificial muscle, and integrally molded the artificial muscle with the increased number of segments. In addition, the design was changed to reduce post-processing after molding. We also discussed the effect of increasing the number of segments on contraction by measuring the contraction of the artificial muscle.

DOI： 10.1299/jsmermd.2020.1p2-h14

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In the inspection of sewer pipes, it is necessary to identify the damaged part, and a pipe diagram is indispensable, but it is often dissipated and many pipe maps do not exist. Therefore, it is required to create pipeline diagrams. Therefore, the authors used an IMU sensor that measures three-axis acceleration and three-axis angular velocity, and corrected the cumulative error that occurred at that time by using the traveling characteristics of the earthworm's peristaltic motion, which is a periodic motion of progression and stopping. We tried to measure the pipe length and the pipe shape. In this report, we conducted a basic evaluation experiment to measure the pipe length with high accuracy, and investigated the effectiveness of this method.

DOI： 10.1299/jsmermd.2020.2a2-h06

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In the recent years, aged pipes are increasing, and many road collapse accidents occur. Therefore, it is necessary to inspect the condition of the pipe to efficiently determine whether a replacement or repair is necessary. However, pressure pipes that are capable of coping with complex terrains, the pipelines are complicated and are difficult to inspect with the existing inspection equipment. Therefore, based on the earthworm's peristaltic movement and artificial muscles, the authors developed a peristaltic robot in a previous research for inspecting the inside of a pressure-feeding pipe. However, owing to the unevenness its joint, the robot was unable to maneuver through the corners of a curved pipe. Therefore, in this study, we developed a high rigid joint attachment that enables the robot to pass through a curved pipe, and evaluated its effectiveness through traveling experiments by using a curved pipe.

DOI： 10.1299/jsmermd.2020.2a2-h07

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© 2019 IEEE. In this paper, we propose an assistance method that controls joint stiffness and the antagonized angle using variable elastic elements. The proposed system changes the stiffness and angle so that they correspond to the phase of movement and performs movement assistance in cooperation with the wearer. To achieve structural variability in the configuration of stiffness and the antagonized angle, we propose a joint structure in which the artificial muscle and tension spring are antagonistically arranged. While performing a movement, motion analysis was conducted to investigate the change in joint stiffness and antagonized angle. We confirmed that the proposed joint and human joint have the same tendency while in motion.

DOI： 10.1109/ICAR46387.2019.8981664

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DOI： 10.1109/IROS40897.2019.8967648

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DOI： 10.1109/IROS40897.2019.8967522

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Copyright © 2019. The Authors. Published by Elsevier Ltd. All rights reserved. In this paper, we propose a method to generate a 3D map in the narrow pipeline from inside images captured from a camera mounted on earthworm robot. Pipes that have reached the end of their useful life cause leaks and pits in the road; thus, it is necessary to inspect the inside of the pipe. In order to inspect the inside of the pipe, images in the pipeline are converted to development images and motion estimation of the camera is performed using the optical flow. Finally, the development images are connected to generate a 3D map.

DOI： 10.1016/j.ifacol.2019.11.053

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Copyright © 2019. The Authors. Published by Elsevier Ltd. All rights reserved. In this study, an experiment is conducted to evaluate a squat motion while using the wearable variable viscoelastic assistive suit “Airsist I,” and the assistive effect of the suit is confirmed. Wearable assistive suits help in reducing the burden on laborers. Airsist I was developed in a previous study, based on the characteristics of variable viscoelasticity. In addition, a variable viscoelastic control strategy was proposed. However, an evaluation has not been performed to confirm the assistive effect of Airsist I. Therefore, this study reports on the confirmation of the assistive effect of the variable viscoelastic suit Airsist I.

DOI： 10.1016/j.ifacol.2019.11.050

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Copyright © 2019. The Authors. Published by Elsevier Ltd. All rights reserved. In the shipbuilding industry, welding is one of the forms of nonautomated heavy labor, and the welding operator is required to weld indeterminate objects in a narrow working space. Therefore, it is difficult to use large equipment, such as industrial robots. In addition, it is not easy to perform high-quality welding, because tracing a welding line accurately at a constant speed requires a long training period. In this research, the aim was to develop a welding assist device that can be applied to a welding environment. The proposed device fixes to the welding surface by magnetic force and assists semiautomatic welding with a magnetorheological (MR) brake. MR brakes have a sufficient response speed compared with powder brakes, have a large output weight ratio, and are considered to be suitable for welding assistance. In this work, a strategy for control of path rendering and speed restriction by MR brakes is proposed. Its effectiveness was confirmed by experiments with a prototype.

DOI： 10.1016/j.ifacol.2019.11.057

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Using a head-mounted display, users can immerse themselves in virtual reality space and users can via the visual recognition of virtual objects. However, users do not experience the same haptic perception when they interact with these objects, that they do with actual objects. Force feedback devices can render haptic perception. They are classified into desktop and wearable types. A wearable 1 degree of freedom force feedback device using magnetorheological fluid brake, magnetorheological clutches, and pneumatic artificial muscles has been previously developed and it was confirmed that the device can render elasticity, friction, and viscosity. In addition, a wearable 4 degrees of freedom force feedback device using magnetorheological fluid clutches and pneumatic artificial muscles that can render elasticity was also previously developed. However, it was not established that the device could render friction, and viscosity using magnetorheological fluid clutches and pneumatic artificial muscles. In this report, it is confirmed that such a device can render friction and viscosity using magnetorheological fluid clutches and pneumatic artificial muscles without the need for magnetorheological fluid brake.

DOI： 10.1109/IECON.2019.8927514

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/AIM.2019.8868604

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DOI： 10.1109/lra.2019.2902016

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In this study, we made the assumption that the feeling of a firm handshake is related to the stiffness of the elbow joint and we performed handshake experiments under variable stiffness conditions to verify the assumption. EMG signals were recorded to be used as an evaluation. Then human-robot handshake experiments were performed utilizing a handshake manipulator proposed in the previous research. The joint of the manipulator was driven by antagonized artificial muscles, which are considered to be soft actuators designed to mimic the movement of real human muscles. The muscle activations of the subject were compared when the subject shook hand with the experimenter and the manipulator. And it has been demonstrated that even though the subject was not aware of the experiment conditions, the muscle activations are higher in the firm handshake condition in both human-human handshake and human robot handshake experiments, which indicated that firmness of handshakes are related to the stiffness of the joint and the EMG signals can used as an evaluation method.

DOI： 10.1109/ICARM.2019.8833897

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：一般社団法人 日本ロボット学会  

&lt;p&gt;Seabed mineral resources were found on the bottom of the ocean. To utilize these resources, it is necessary to collect and analyze samples. Therefore, we intend to develop a seafloor robotic explorer that can excavate and sample the seafloor soil. In a previous study, we developed a drilling robot and experimentally demonstrated the ability of this robot to produce curved boreholes with a turning radius of 1,670[mm], and a depth of 613[mm] in land environment. However, an underwater excavation has not been successful. It is necessary to improve the gripping torque and to reduce the drilling resistance for underwater excavation. In this paper, we present a propulsion unit with the setae that imitates an earthworm&#039;s setae. As a result, the drilling robot succeeded in drilling into the ground while underwater. In addition, we aim to reduce the drilling resistance. We adjusted the penetration speed and the rotational speed of the drilling robot based on the drilling properties of underwater ground. We also consider the shape of the earth auger to reduce the drilling resistance. As a result, we succeeded in reducing the drilling resistance, which both lowered the excavation energy by 39.2% and reduced the completion time. &lt;/p&gt;

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DOI： 10.1109/ACCESS.2019.2930994

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Japan Society for Aeronautical and Space Sciences  

DOI： 10.2322/tastj.19.211

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In this study, a handshake manipulator with variable viscoelastic joints was proposed. The variable viscoelastic joint system comprised of antagonized artificial muscles and a magneto-rheological fluid brake. This joint system resembles the characteristic of real human joint. The objective of this study is to evaluate the proposed manipulator's effectiveness in the research of human-robot physical interaction and to verify that by adjusting the viscosity and stiffness of the joint it is possible to create handshakes with different feelings. In this research two sets of experiments were conducted; the first set of experiments was to conducted on the manipulator alone in order to test the performance of the manipulator. And the second set of experiments was the subjective evaluation of the manipulator when subjects shook hand with the manipulator under variable viscosity and stiffness conditions. The results of these experiments indicated that the manipulator was suitable for doing research on human-robot handshake, and the variable viscosity and stiffness of the elbow joint did create distinctive feelings to the subjects.

DOI： 10.1088/1361-665X/ab0d9b

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A dielectric elastomer actuator (DEA) is a soft actuator with low manufacturing cost and high energy efficiency. The structure of a DEA consists of a dielectric material interlayered with elastic electrodes, and DEA expands when an electric field is applied. The degree of freedom of movement of the DEA can be increased by devising the electrode arrangement in DEA. The performance of DEA is determined by permittivity, Young's modulus, and applicable electric field. Material properties including hysteresis loss are also important when a DEA is used as a sensor or high precision actuator. Generally, silicon and acrylic rubbers are used as the dielectric layer. This study focused on the use of a slidering material (SRM) as a more suitable dielectric for DEA than silicone and acrylic rubbers in terms of its dielectric constant and hysteresis loss. In a previous study, a DEA was developed using SRM as a dielectric, and the image correlation method (ICM) was applied to measure the strain distributions in a two-dimensional plane and the basic characteristics of DEA with one pair of electrodes. Here, the strain distribution was measured when the electrodes of the DEA were segmented into several pairs as the next step in the investigation of its basic characteristics. Patterns of electrode arrangements and the amount of DEA prestretching were changed, and strain distribution was measured using ICM.

DOI： 10.1117/12.2514194

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Various types of soft actuators have been developed for application in wearable movement-assist devices or soft robots. The authors have developed a straight-fiber-reinforced pneumatic rubber artificial muscle (SF-ARM). The SFARM is composed of rubber that is reinforced with fibers aligned only in the axial direction. When air pressure is applied to the SF-ARM, the reinforced fibers limit the rubber expansion to the radial direction so that the muscle contracts in the axial direction. The SF-ARM contracts by 38% at maximum, and this contraction rate exceeds the contraction rate of the McKibben artificial muscle. However, the SF-ARM is not well-suited for practical use because the strain on the SF-ARM while it is actuated is large which can cause fatigue failure of the rubber. This study focuses on suppressing the growth of cracks using strain-induced crystallization of the natural rubber, to prolong the lifetime of the SF-ARM. Natural rubbers form a crystalline layer in the direction perpendicular to the direction of stretching. This crystal layer effectively suppresses the growth of cracks in the SF-ARM when under strain. Deliberately developing a crystal layer should extend the lifetime of the SF-ARM. First, this study confirmed the formation of a crystal layer under extension of natural rubber (NR) and styrene butadiene rubber (SBR) using wide-angle X-ray diffraction measurements. Next, the strain concentration near the crack was analyzed using finite element method simulations. Finally, fatigue-life tests were conducted with SF-ARMs made of NR and SBR.

DOI： 10.1117/12.2513246

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DOI： 10.1109/SII.2019.8700347

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DOI： 10.9746/sicetr.55.59

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Dielectric elastomer actuator (DEA) is a soft actuator with low manufacturing cost and high energy efficiency; it expands when an electric field is applied. The structure of DEA comprises a dielectric material interlayered with elastic electrodes similar to a sandwich. The performance of DEA is determined by the material of the dielectric layer, which is generally silicon or acrylic rubber. This study focused on investigating the characteristics and various applications of slide ring material (SRM) as a dielectric. SRM is more suitable for use as a dielectric of DEA as compared to silicone and acrylic rubbers in terms of the dielectric constant and hysteresis loss. Several measurement methods of existing DEAs measure only uniaxial deformation. However, the actual DEA strain distribution is not completely uniform. In addition, obtaining the two-dimensional (2D) strain distribution leads to a better understanding of the lifetime and performance of DEA as DEA deforms in 2D practical applications. Therefore, this study measured the strain on the DEA, while changing the load, applied voltage, and number of layers, using the image correlation method, which is a 2D planar measurement method. This measurement confirmed the two-dimensionally spreading strain distribution. The relationship between the stress, strain, and number of DEA layers was also obtained.

DOI： 10.1109/SII.2019.8700353

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DOI： 10.1109/SII.2019.8700416

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DOI： 10.1109/SII.2019.8700462

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：日本フルードパワーシステム学会  

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Japan Fluid Power System Society  

<p>Pneumatic rubber artificial muscle is attracting attention as an actuator having high cooperativeness with human because of its feature of being flexible and lightweight. The authors have developed Straight fiber type pneumatic artificial muscle (SF-ARM), which is a high power, highly displaced pneumatic rubber artificial muscle. Although SF-ARM has excellent contraction characteristics, it has a problem of short fatigue life. Therefore, in this study, focusing on strain-induced crystallization of natural rubber, the fatigue life of SF-ARM has been extended. First, strain-induced crystallization of natural rubber were confirmed by wide angle X-ray diffraction. Next, analysis of strain concentration in the vicinity of the crack was performed by the finite element method. Finally, a fatigue life test of SF-ARM was carried out to confirm the effect of prolonging the fatigue life by using strain-induced crystallization.</p>

DOI： 10.5739/jfps.50.46

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Society of Instrument and Control Engineers  

<p>There are many pipe-systems such as a water pipe, a gas pipe and a ventilation duct in a plant, factory and house. The inspection of these pipe-systems is necessary to prevent accidents and malfunctions. However, many pipes are very narrow, and it is difficult for people to inspect directly. In this study, a brush wheel type robot which has the simple and compact drive mechanism and does not need large space to move, is proposed. When moving inside of a pipe, this robot uses the elastic force of a brush wheel to hold the robot in pipe. Additionally, the robot can move a vertical pipe and a curved pipe by replacing the brush wheels. This paper reports the robot's structure, the drive mechanism, the operation principle, the prototype evaluation and three type pipe running experiments.</p>

DOI： 10.9746/sicetr.55.692

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：CLAWAR Association Ltd, UK  

Robots are expected to substitute for humans for work performed in locations at a height, such as the inspection of an airplane surface. The authors propose a traveling-wave-type wall-climbing robot simulating a snail movement. To this end, in this study, the negative pressure adsorption method was employed to develop a wall-climbing robot that could move on curved surfaces for high-altitude work.

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The authors have developed a small excavation robot called the “LEAVO” for lunar exploration, and they have confirmed its usefulness as an excavation robot. They then attempted to add a curved excavation function in order for the LEAVO to increase its exploration field. To achieve this goal, it was necessary for the LEAVO's excavation unit to transmit the motor output torque to the excavation head without any losses. In this paper, therefore, the authors proposed a new driving system called the “distributed driving system,” which reduced the transmission losses by distributing the actuators and arranging them in the frontal part of the robot. Moreover, the authors developed the prototype of this system and measured its output torque as an operational check.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The pneumatic soft actuator converts the input energy by utilizing structural deformation or material deformation according to the applied pressure to obtain the output. Although various forms of operation are conceivable, in practice it was difficult to freely design under manufacturing constraints. In recent years, with the development of 3D printers, flexible materials such as rubber as well as hard materials such as conventional resin can be printed. It is now possible to manufacture an actuator having a complicated shape combining a resin material and a rubber material that have been difficult to produce. In this paper, Pleated Pneumatic Artificial Muscles using 3D printer which can design freely using resin and rubber material with fabricated and evaluated contraction characteristics.

DOI： 10.1299/jsmermd.2019.2a1-c07

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/IROS.2018.8593436

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DOI： 10.1109/IROS.2018.8594397

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DOI： 10.20965/jrm.2018.p0752

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (other academic)   Publisher：日本フルードパワーシステム学会  

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

In this paper, we developed a propulsion unit with bristles imitating the setae of earthworm. This propulsion unit is installed in SEAVO: sub-seafloor excavation robot. To realize underwater excavation by SEAVO, it is necessary to move the soft and fluid sedimentary layer of seafloor surface. As a solution, we focused on the setae of earthworm which live in mud and soft soil. Then, we developed the propulsion unit with bristles imitating the earthworm's setae and measured the performance of the setae-attached propulsion unit. Comparing the measurement result of the bristlesattached propulsion unit with the previous propulsion unit, we confirmed the usefulness of the bristles-attached propulsion unit.

DOI： 10.1299/jsmermd.2018.2p1-a07

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Pneumatically driven wearable assistive devices for walking have been developed recently. These devices can achieve flexible assistance without control; however, they require large and heavy air compressors for activation. In this study, a pneumatically driven source using vibration energy regeneration from walking was developed. The aim was to activate the cylinder using vibrations due to walking and compressed air. A mass element, which is connected to a human body via a spring and a cylinder, vibrates along with the human gait cycle. Next, a prototype was developed and tested. In walking experiments, stored pressure was measured at several gait cycles and masses for comparison. Results indicate that the gait cycle period and masses affect the stored pressure; the highest pressure recorded was 0.08 MPa.

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DOI： 10.1109/BIOROB.2018.8487219

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J-GLOBAL

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DOI： 10.1109/BIOROB.2018.8487902

J-GLOBAL

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DOI： 10.1109/AIM.2018.8452392

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DOI： 10.1109/AIM.2018.8452696

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

Marine resources exist on the seabed, and sampling is useful for a detailed study of these resources. In general, a pipe-shaped sampler is used to collect marine resources for investigation. However, this is inefficient for investigating sediments, which are widely distributed, because the sampling range is limited to the pipe penetration part. A wide area exploration can be made possible by deploying multiple robots to autonomously search beneath the seabed. In a previous study, we developed a seabed robotic explorer called "SEAVO" and experimentally demonstrated the ability of SEAVO to produce curved boreholes with a turning radius of 1.67 m, and a depth of 613 mm, in the land environment. However, underwater excavation has not been successful. Reduction in the drilling torque is necessary for underwater excavation. In this paper, we propose a water jetting excavation method to reduce the drilling torque.

DOI： 10.1299/jsmermd.2018.2p1-b09

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

For lunar underground explorations, we have developed lunar earthworm-type excavation robot “LEAVO” and achieved vertical excavation with it. Then, we now wrestle about curving excavation to make the LEAVO be able to collect some samples in particular layer efficiently. To achieve the curving excavation, it is necessary for the LEAVO's excavation unit to excavate target diameter borehole certainly because the LEAVO become to be inoperable in the excessively large or small diameter borehole. To excavate target diameter borehole certainty, in this paper, we develop the “both-ends supported flexible auger” as the LEAVO's flexible excavation unit and carry out its characteristics test. Moreover, we confirm its usefulness in the axis runout check and excavation test.

DOI： 10.1299/jsmermd.2018.2a2-a08

DOI： 10.2322/tastj.19.211_references_DOI_4nb5xJuaOYkd4ciEK3vIF4vm7C9

CiNii Research

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (other academic)   Publisher：環境新聞社  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Robotics Society of Japan  

Infrastructure pipes require inspection in order to prevent accidents. However, it is difficult to inspect a 1-in-diameter gas pipe because it is long, narrow and complicated. Therefore, an earthworm-type robot was developed to inspect this 1-in pipe. The robot moved by peristaltic crawling with pneumatic artificial muscles and displayed its suitability as a 1-in pipe inspection robot in experiments. However, its speed was extremely slow to be practically utilized. A major cause for this is the small distance covered in a single motion of the robot. Therefore, in this study, we developed an axial extension actuator to increase the moving distance of the robot in a single motion. Furthermore, we installed this new actuator on our robot and made it possible for the robot to change the morphological motion in peristaltic crawling. The experiments with straight and elbow pipes ascertained the importance of morphological change in peristaltic crawling for increasing the speed of the robot. Moreover, in a continuous elbow pipe, the velocity of the proposed robot was 5.5 mm/s, which is 1.3 times faster than that of the conventional robot. Consequently, we confirmed that the speed of the proposed robot was sufficiently fast for inspecting a 1-in pipe.

DOI： 10.1080/01691864.2017.1417158

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/ROBOSOFT.2018.8404893

J-GLOBAL

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DOI： 10.7210/jrsj.36.233

J-GLOBAL

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

This letter proposes a novel hybrid pneumatic power source for the development of a portable pneumatic source. The hybrid pneumatic source achieves a lightweight system by combining two pneumatic sources: one that can generate high pressure/small suppliable flow and one that can generate small pressure/large suppliable flow. In this study, first, the mobility of various pneumatic sources is evaluated by experiments. The evaluation methods involve a small battery-driven compressor, tank, phase change of material, and chemical reaction. From the results, it is clarified that there is no best method because each method has advantages and disadvantages. Then, a hybrid pneumatic source utilizing the result is proposed. Finally, a prototype that has phase change of CO2 and dimethyl ether as a pneumatic source is developed, and the effectiveness of the proposed method is confirmed by experiments.

DOI： 10.1109/LRA.2018.2792145

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DOI： 10.1109/ROBOSOFT.2018.8404918

J-GLOBAL

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DOI： 10.18974/tvrsj.23.1_45

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In this study, a variable viscoelastic joint system with a clutch for human assistance was proposed. The variable viscoelastic joint system comprised antagonized artificial muscles and magneto-rheological fluid brake. This system enabled the human assisting device, such as exoskeletons, to retain structural softness when compared with the existing devices driven by motor and reduction gear, which could only achieve superficial softness. In addition, a clutch system that provided high back-drivability to the wearer by structurally separating the device from the wearer was proposed. As an initial step in designing the human assisting device, a prototype with the proposed variable viscoelastic joint system for knee assistance is developed. Also, its control method was developed. Furthermore, experiments were conducted to confirm the influence of the proposed viscoelastic joint system and control method on the wearer.

DOI： 10.1177/1045389X17705216

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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DOI： 10.9746/sicetr.54.2

J-GLOBAL

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Robotics Society of Japan  

<p>Recently, assisting human motion with a wearable robot is studied widely. These assisting systems are proposed from various points of view. Our study has proposed an assisting system that the torque, angle, and the viscoelasticity of the joint are variable because the human muscle has the characteristic of variable viscoelasticity. This system consists of antagonized muscle that the stiffness is variable and magneto-rheological fluid brake that the viscosity is variable. Therefore, the system enables the wearable assistive device such as exoskeletons to be structurally soft and to provide the wearer with a high back-drivability. We have proposed the assisting method by changing the viscoelasticity of the device joint according to the viscoelasticity of wearer's muscle. But suitable viscoelasticity of the joint for the assistive motion is not well known. In this paper, an experiment is conducted to examine how the viscoelasticity of the joint affects to human motion when assisting. Also, based on the results from the experiments, we propose the control method for the joint viscoelasticity of the device that responds to the assistive motion and confirm the effects with the experiments. </p>

DOI： 10.7210/jrsj.36.567

CiNii Books

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/ROBIO.2018.8664749

J-GLOBAL

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2018 IEEE. In recent years, because the development of space technology has been increasing for the purpose of improving the social infrastructure, the expansion of space transportation systems based on low-cost and high-frequency rockets is important. Solid propellants used in solid-fuel rockets have properties of the compactness, inexpensiveness, and easy-handling. However, solid propellants are highly viscous slurries and highly explosive. As there is no device capable of continuously and safely transporting solid propellant, the process of manufacturing solid propellant is a batch process. We focused on the movement of human intestines that knead and transport with a small force as part of the development process. In this report, we design a mechanism for the mixing process by using a peristaltic mixing transporting device for efficiency and by automating the equipment. Specifically, we conduct two experiments with samples using an adjusted fluid ratio: A comparison experiment on fluidity and a pressure response experiment. We investigate the possibility of automatic control and efficiency by using the factors of pressure and flow rate.

DOI： 10.1109/BIOROB.2018.8487789

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

<p>In recent years, because development of space technology has been increasing for the purpose of improving social infrastructure, the expansion of space transportation system based on low-cost and high-frequency rockets is important. Due to the compactness, inexpensiveness, and easy-handling properties of solid propellants used in solid-fuel rockets, numerous studies on solid propellants have been conducted. However, solid propellants are highly viscous slurries and highly explosive. As there is no device capable of continuously and safely transporting the solid propellant, the process of manufacturing the solid propellant is a batch process. We focused on the movement of human intestines that knead and transport with a small force, as part of the development process. In this paper, we developed a peristaltic pump, Mk. III, for kneading a solid propellant. The pump was comprised of a heating system, an input device for the powder and fluid, and a rapid exhaust valve. An investigation into the amount of input of the raw materials was undertaken, and the tendency of kneading at the point of introduction of the powder and highly viscous fluid was determined.</p>

DOI： 10.2322/tastj.16.662

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>The cylindrical rubber is axially reinforced by the fiber and closed by the rigid ends. When the inner pressure is applied to this fiber reinforced rubber cylinder, the diameter expands and the length shrinks. Such the cylinder can be used as the soft actuator, that is, the artificial muscle. In this paper, this problem is analyzed theoretically. Firstly, the differential equation, which is satisfied the cylinder's profile, is derived. Secondary, the solution is obtained as the closed form, when the rubber is soft enough compared to the fiber. Finally, it is found that the profile of the rubber cylinder is given by the incomplete elliptic integral, when the inner pressure is large enough. Moreover, the spring constant, the contraction ratio and the maximum stress are obtained with respect to the length of the cylinder. The spring constant is linearly increasing with the inclement of the initial length of the cylinder. The contraction ratio is increasing with the inclement of the initial length of the cylinder and converged to 54.3%. The maximum stress is related to the elastic modulus of the rubber and is not related to the inner pressure. When the length of the cylinder is through three to five times larger than the initial diameter of the cylinder, the rubber has the small maximum stress and the large contraction ratio.</p>

DOI： 10.1299/transjsme.18-00351

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Powder-based materials are widely used in various applications such as printing. In printing, low shear force and high-speed conveyance at low temperatures are required to prevent creating defects in materials. In a previous study, we developed a transportation device based on the human intestinal tract that successfully transported highly viscous and solid-liquid fluid mixes and powder material. In this study, we developed a tubular peristaltic conveyor capable of transporting powdered materials in a printer under the aforementioned conditions. The conveyor had a triangular cross-sectional area and a small air chamber to facilitate high-speed peristaltic motion. The performance of the conveyor was confirmed experimentally, and we achieved a conveyance rate of 81.5g/s.

DOI： 10.1080/01691864.2018.1491089

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：日本フルードパワーシステム学会  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：World Scientific Publishing Co. Pte. Ltd.  

In this study, a peristaltic crawling robot that is capable of traveling over 100 m in a 100A pipe was developed. The performance of new robot was evaluated by conducting experiments in straight horizontal and vertical pipes, a 90° large curved pipe, and a 90° elbow pipe, as well as in a real sewer pipe line. A running experiment with a pressure feed pipe was performed and its usefulness was verified. Currently existing robot (PEW-RO) has low robustness and running speed in a real environment which is insufficient for practical applications. Herein, based on previous research, a new peristaltic crawling robot (PEW – RO Ad) is developed and a running test in a long distance pipe was conducted. The obtained results are compared with the running performance and robustness of the currently existing robots.

DOI： 10.1142/9789813231047_0013

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：World Scientific Publishing Co. Pte. Ltd.  

In our previous study, we developed a lunar subsurface excavation robot that mimicked the peristaltic crawling movement of an earthworm. The robot excavated soil by using an earth auger and propelled in a hole by using peristaltic crawling. however, the earth auger could not be positioned properly. Consequently, the diameter of the hole took not constant value and the robot’s ability to propel was reduced. In this paper, to overcome this problem, we have developed a both-end supported earth auger and demonstrated its performance by comparing it with existing earth augers.

DOI： 10.1142/9789813231047_0012

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE Computer Society  

A body fixing method for wearable assistive devices was proposed that utilized jamming transition and the expansion of an elastic bag. The proposed fixing part comprised a jamming layer, a rubber bag, and other components. The jamming layer deformed due to the application of pressure to an elastic bag. Then, it hardened due to negative pressure. In this research, we described the configuration and movement of the proposed method and conducted a sensory evaluation using a prototype.

DOI： 10.23919/ICCAS.2017.8204222

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Authorship：Last author,　Corresponding author   Language：English  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A body fixing method for wearable assistive devices was proposed that utilized jamming transition and the expansion of an elastic bag. The proposed fixing part comprised a jamming layer, a rubber bag, and other components. The jamming layer deformed due to the application of pressure to an elastic bag. Then, it hardened due to negative pressure. In this research, we described the configuration and movement of the proposed method and conducted a sensory evaluation using a prototype.

Web of Science

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J-GLOBAL

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Robotics Society of Japan  

Recently, low back pain of laborer is social issue in Japan. This problem is caused by excessive load on waist joint or uncomfortable posture of heavy labor, such as lifting up heavy objects. To resolve the problem, we have developed endoskeleton-type power assist suit. In previous study, the design and operation method of the assist suit was designed using simple static model. However, this method is insufficient for designing the assist suit because structure of human body is more complex than the model practically. Therefore, we use the musculoskeletal model to design the assist suit and its operation method in this paper. Firstly, motion of worker is analyzed using 3D motion capturing and this results are applied to musculoskeletal model &ldquo;Anybody&rdquo;. Secondly, with these simulation results, the assist suit and its operation method are designed. Finally, effectiveness of the assist suits confirmed by measurement of electromyography and assistive force.

DOI： 10.7210/jrsj.35.557

CiNii Books

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J-GLOBAL

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/iros.2017.8202272

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In recent years, ventilation equipment has been installed in various structures to draw in outdoor air and circulate indoor air. These ventilation installations have pipes (ducts) through which air flows. If dust accumulates in a duct, it will be carried indoors by the airflow. Dust adversely affects human health, and so these ducts must be cleaned regularly. However, the existing cleaning methods are inadequate for the Ducts having small diameter and many curved points, that are used in houses. Thus, to clean such ducts, we have developed a robot that moves imitating peristaltic crawling. This motion is suitable for moving in ducts because it is stable in curved and narrow pipes. In addition, the robot can move and clean the duct at the same time because it moves forward by holding the pipe walls. In this paper, we outline the development of such a robot. From the results of using the robot to clean the inside of duct, we find a cleaning performance of it.

DOI： 10.1109/AIM.2017.8014192

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In this study, we developed a wall-climbing robot for airplane body inspection. To move on airplane body, the robot needs to move on walls and curved surfaces. A traveling-wave-type, omnidirectional wall-climbing robot that uses magnetic force to adhere could move on such a wall and curved surface. However, magnetic force cannot be used to adhere to airplane body. Therefore, we developed a wall-climbing robot that uses negative pressure suction to adhere and move on airplane body. We performed basic experiments on the robot and designed the robot based on the experimental results.

DOI： 10.1109/AIM.2017.8014032

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Lower back pain is a major health concern worldwide. One cause of lower back pain is the burden on the lumbar region caused by the handling of heavy objects. To reduce this burden, the Ministry of Health, Labour and Welfare in Japan has recommended 'squat lifting.' However, this technique, which supports a large force on lower limbs, is not very popular. Therefore, we aimed to develop a power assist suit for squat lifting. In this paper, we propose a gastrocnemius-reinforcing mechanism. Next, we discuss estimation of joint torque from motion analysis of squat lifting in order to construct a prototype. Finally, we describe the performance of the prototype mounted on a human body. The %MVC of the gastrocnemius while performing squat lifting was reduced by 34% using the prototype assist suit compared with the value without using the suit.

DOI： 10.1109/AIM.2017.8014124

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

If pipes with narrow diameters are not well inspected, preventing accidents become difficult. Therefore, we developed a pneumatically powered earthworm-type robot for Half-inch pipes (each having an inner diameter of approximately 16 mm)
these pipes are extremely difficult to inspect. When the robot travels for a long distance, its speed significantly decreases. When the movement distance of one cycle is small and the inter-operation period is short, the influence of the response delay of the pneumatic actuator increases and the speed decreases. Therefore, we developed a robot whose response delay is less likely to influence the driving speed and that has a large amount of movement per cycle. To create the proposed robot, we developed an extension unit and a grip unit as pneumatic actuators and experimented on pneumatic response characteristics. Also, the driving speed was measured using running tests. This confirmed that the robot's speed increased, and the speed decay owing to the long air tube decreased. The proposed robot will help reduce accidents arising from the corrosion of pipelines.

DOI： 10.1109/AIM.2017.8014035

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In recent years, road collapse accidents due to leakage of aging sewage pipes have become a major social problem. To prevent accidents, the inside of the sewage pipe must be inspected. However, it is difficult to inspect long-distance pipes with diameters of 100 mm or less and curved pipes. Therefore, in this research, we develop an inspection system that uses earthworm movement which can drive steadily over long distances even in narrow spaces. This research involves traveling experiments on straight horizontal pipes, straight vertical pipes, and 90° pipes, and the usefulness of the proposed approach is confirmed. In this report, we present the device to estimate the shape of sewer pipelines and confirm its usefulness by experiment.

DOI： 10.1109/AIM.2017.8014194

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In this study, we developed a 4-degrees of freedom (DOF) force feedback device independent of its operational component comprising pneumatic artificial muscles and magnetorheological clutches. Research and development of force feedback devices is becoming popular in fields such as entertainment, remote operation, and rehabilitation. These areas of research are related to virtual reality and augmented reality. People are focusing their research efforts on force feedback devices that display three-dimensional virtual objects or can provide realistic force sensing as that of stroking the surface of a virtual object. Many of these devices comprise motors
hence, they are likely to be hazardous in the event of delayed response to an unexpected external force. In addition, their back drivability decreases when the motor output is increased via reduction gears. To solve these problems, we previously developed a 3-DOF force feedback device using pneumatic artificial muscles, which are structurally flexible and have a wide range of stiffness, and magnetorheological clutches. As the next step toward developing a 6-DOF device, we have developed a 4-DOF feedback device.

DOI： 10.1109/AIM.2017.8013998

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Unmanned rescue, observation, and/or research vehicles with high terrain adaptability, high speed, and high reliability are needed in difficult-to-reach locations. However, for most vehicles, high performance over rough terrain reduces the travel speed and/or requires complex mechanisms. We have developed a blade-type crawler robot with a very simple and reliable mechanism, which traverses uneven terrain at high speed. Moreover, the gyro wheel design stabilizes the success of this approach in improving the motion, ensuring robust traversal. The improvement in traveling speed and robustness over uneven terrain by our approach was confirmed by experiment.

DOI： 10.1109/ICRA.2017.7989555

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In recent years in Japan, over half of all workers suffered from lower back pain. This has become a social problem that needs to be addressed. To reduce its occurrence, we developed a flexible, high-output waist assist suit called 'AB-Wear' in a previous study. The AB-Wear suit can assist human motion and reduce muscular fatigue of the waist. However, the assistive forces of the device generate compressive forces on the backbone, which have adverse effects on the body. Hence, in this study, we propose an exoskeleton-type AB-Wear equipped with a compressive force reduction mechanism, called 'semi-endoskeleton-type AB-Wear'. This device has a reduction mechanism similar to a flexible flat spring behind the upper body. Because of this structure, this device can generate an effective assistive force. First, we explain the difference between the semi-endoskeleton-type AB-Wear and the previous device. Then, we model the semi-endoskeleton-type AB-Wear because the model is used for its operation. Moreover, its effectiveness is confirmed using musculoskeletal simulation. Finally it is evaluated by measuring surface electromyography (EMG) on a subject's body to confirm its effectiveness with a real body. The EMGs of the wearer with and without the suit are compared. The usefulness of the AB-Wear is confirmed by simulation and experiment.

DOI： 10.1109/ICRA.2017.7989711

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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DOI： 10.5739/jfps.48.17

J-GLOBAL

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SAGE PUBLICATIONS LTD  

This article focuses on developing a pneumatic artificial muscle as a variable elastic device and a magnetorheological fluid brake as a variable viscosity device and a variable friction device. We executed a throwing motion using a 2-degree-of-freedom manipulator as a case study of the control of dynamic motion. To investigate the throwing motion, we proposed the spring model of the manipulator, which includes a variable viscoelastic joint. Next, the manipulator and the spring model were extended to 2 degrees of freedom. In addition, the spring model was verified by comparing the simulation and experimental results. The simulation results reproduced the experimental results. Furthermore, we maximized the velocity of the end effector during the throwing motion by searching for adequate drive timing of the second joint in the simulation. In the simulation, hand speed was improved by releasing the second joint on the basis of the angular acceleration of the first joint. Finally, the simulation results were reproduced experimentally under the same conditions.

DOI： 10.1177/1045389X16641202

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Authorship：Last author,　Corresponding author   Language：Japanese  

DOI： 10.7210/jrsj.35.153

CiNii Books

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Authorship：Corresponding author   Language：Japanese  

DOI： 10.7210/jrsj.35.230

CiNii Books

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Robotics Society of Japan  

Recently, about 60% of worker suffers from low back pain in Japan. Hard working such as lifting and carrying provides a load to waist joint, and worker gets low back pain. So, we developed a power assist suit to reduce the load of waist joint. This assist suit has various futures; endoskeleton, high output and flexibility, because this device moves using two pneumatic actuators. This device generates active and passive assistive force. These forces can assist human motions according as situations. First of all, we analyzed the human motion by motion capturing software. The analysis results are substituted into human link model, and load of human body is estimated. Thus, we decided design and operation method of the assist suit using analysis results and a static assist suit model. The motion of wearer is &ldquo;lifting up motion&rdquo; and &ldquo;carrying motion&rdquo; in evaluation experiments, because these motions are frequently performed in manufacturing plant work. Each assistive force assists these motions, and effectiveness of assist suit was confirmed from decrease of electromyography (EMG) in wearing.

DOI： 10.7210/jrsj.35.70

CiNii Books

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Sub-seafloor exploration is important for biological and geological research. One of the major exploration tasks is the sampling of mud containing mineral resources and that of marine sediments. We designed a peristaltic-crawling sub-seafloor excavation robot comprising three units for propulsion, excavation, and extraction. The robot was designed to move freely under the seabed and was fitted with a flexible earth auger using universal joints, designed to operate in a bending state. We experimentally tested the performance of the earth auger and excavation unit under bending states with constant curvature. The ability of the auger to excavate and convey soils while in the bending state was confirmed.

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In this study, we developed a peristaltic crawling robot with earthworm locomotion as a test device for the long-distance inspection and maintenance of pressure feed pipes with narrow diameters and complex layouts. This robot uses pneumatic artificial muscles to reproduce an earthworm's movements. Using the developed robot, we conducted a driving experiment using a mock pipeline including actual pipes with a pressure feed pipe. We also verified the driving performance of the robot in a real environment.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This study focuses on proposing an adhesion unit for an omnidirectional robot that can inspect the body of an airplane and check its properties. We reveal relations of the adhesive force generated by the centrifugal fan with the adhesive part size, number of centrifugal fan revolutions, and leakage area between the unit and airplane body. We calculated the leakage area, and the unit was designed considering these results.

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As a manual inspection process is inefficient and dangerous, it is desirable for the inspection of an airplane body to be automated by employing a wall-climbing robot. We have previously developed a traveling-wave-type omnidirectional wall-climbing robot. The robot specialized in a large contact area for ground and omnidirectional movements and can potentially conduct an inspection of an airplane body if it is installed with a negative pressure suction mechanism. In this paper, we consider techniques to install negative pressure suction to this robot.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Recently, improvements in robots with human affinity have become necessary. Such robots need artificial muscles that are similar to human muscles. This improvement can be achieved by designing a telescopic actuator comparable to that of a human muscle cell. We studied a shape memory alloy actuator protected by a rolled film tube. In this study, the actuator was inserted into a natural rubber tube for portability. We investigated the fundamental characteristics of the actuator and experimented with its antagonistic stiffness control.

DOI： 10.1109/AIM.2016.7576770

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

In recent years, powdered materials have been often used in various industries. Among the various uses of powders, we focused on the conveyance of the developer in the printers. Screw conveyors are commonly used in the printer for the conveyance of the developer. However, this presents the problems such as the condensation of the developer by the shearing force and the temperature rise. Thus, low shear and high-speed conveyance at a low temperature is required. In an alternative approach, we developed a transport device that mimics the intestinal tract and demonstrated successful transport of the highly viscous and solid-liquid mixed fluids. In this study, to overcome the above problems, we considered the peristaltic conveyor. We investigated the ability of this conveyor to convey powder by using the expansion of the rubber. In this work, we performed conveyance experiments by using the carrier used in the printer and measured the weight to determine the conveyance performance per unit of time. By measuring the changes in the conveyance amount due to the changes of the motion interval time, we determined the condition for obtaining the maximum conveyance amount. We then determined the conveyance amount per unit time for the developer.

DOI： 10.1109/AIM.2016.7576989

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Society of Instrument and Control Engineers  

The endoskeleton humanoid robot needs an artificial muscle that is comparable with a human muscle from a viewpoint of form, flexibility, output force, output displacement and the responses. For this realizing, we are studying a Shape Memory Alloy (SMA) actuator that protected by a rolled film tube have the high heat resistance and the high flexibility. In this study, this actuator is inserted into a natural rubber tube for mobilizing and experimented about its antagonistic stiffness control.

DOI： 10.9746/sicetr.52.103

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Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved. The target of this study is to realize the continuous solid propellant producing technique for a cost reduction of solid rocket motor systems. In the process of the solid propellant manufacture, the mixing process controls the quality of the loaded solid propellant; the batch process is impossible to be replaced at present. We have considered the peristaltic pumping action mixer as one of the candidates for the continuous mixer. This mixer system is based on the artificial muscle actuator (soft actuator), and it is elongated and contracted by the pressurized gas. The system has some segments that has double rubber pipes (inner/outer), and the units can work independently. The outer rubber tube controls the shape change direction; the inner one works as a mixing chamber. The outer tube is swollen by the pressurized gas and the segments constrict axially; the inner tube inflates and the free volume can be changed. We expected that this mixer system has possible to replace the batch process by the continuous one. The peristaltic motion enables not only the mixing but also conveying even high viscosity slurry. The mixing mechanism by the soft actuator compress has no impact for the safety of the solid propellant handling. In this research, the mixing completeness of the composite solid propellant slurry by the peristaltic pumping mixer was estimated. The dispersion of the particle materials in the binder and the existing voids was observed by the X ray CT microscope. The solid propellant samples were made by our mixing system. The test materials were as follows: Hydroxyl terminated polybutadiene (HTPB) polymer as for the binder, aluminum powder as for the metallic fuel, dioctyladipate as for the plasticizer, ammonium perchlorate particles as for the oxidizer. The propellant composition was HTPB/AP/Al = 14/68/18 in massThe result showed that the mixer we proposed could mix the propellant slurry. The X ray CT scanning images showed that the solid materials well dispersed through the analysis of the luminance histograms.

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It is difficult to research small diameter pipes using conventional devices. In order to solve this challenge, this paper focuses on the locomotion of an earthworm that is capable of moving stably in a narrow space. A peristaltic crawling robot was developed which was capable of traveling 100 m through a 100A specification pipe using a peristaltic movement. However, especially in long distance inspection, and in elbow pipe, friction force between cable and pipes are too larger to ignore. Therefore, the friction force makes the robot impossible to inspect for long distance. And the friction force injure the cable and air tube equipped in the robot. In this paper, we developed an attachment to reduce the friction force. Using this device, we conducted experiment to measure friction in elbow pipe, and confirmed its effectiveness.

DOI： 10.1007/978-3-319-43506-0_51

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The performance of a robot can be enhanced by increasing its output. However, increasing the output of rigid actuators such as motors and hydraulic actuators will likely increase the weight of the robot. Conversely, organisms such as human beings achieve high output within a short time by accumulating and releasing the elastic energy stored in their muscles; thus, providing an instantaneous force. Moreover, the viscoelastic properties of muscle enable organisms to control their instantaneous force outputs and overall movements. Therefore, in this study, we developed a manipulator with two-degree-of-freedom (DOF) variable viscoelastic joints. The manipulator comprised straight-fiber-type artificial muscles and a magnetorheological (MR) brakes. The ability of a manipulator to generate controlled movement from an instantaneous force was tested in a throwing operation. This simple two-DOF variable viscoelastic manipulator with apparent viscosity control by the MR brakes achieved successful throwing motions. However, it was not possible to calculate the experimental parameters from the target operation in previous study. Therefore, we focused on particle swarm optimization (PSO) as a parameter search method. In this paper, we try to optimize parameters of the throwing movement by combining the spring model of a two-DOF variable viscoelastic manipulator with the PSO method.

DOI： 10.1080/01691864.2016.1217272

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Unmanned rescue, observation and/or research vehicles with high terrain adaptability, high speed, and high reliability are needed to reach difficult locations. However, most vehicles achieve improved performance over rough terrain at the expense of low speed and/or complex mechanisms. We developed a blade-type crawler robot with a very simple and reliable mechanism, capable of traversing uneven terrain at high speed, using aerodynamic devices. As these small devices are in the low Reynolds number region, we tested a wing that made use of the ground effect. We experimentally confirmed the success of this approach in improving the traveling speed and ability to traverse uneven terrain. The robot with aerodynamic lift was climbed 1.5 times higher obstacle than without wings.

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A desktop force feedback device is able to render reaction force of virtual objects. However, the desktop type limits operator's motion. In contrast, a wearable force feedback device allows us to interact with virtual objects while moving in virtual space. In this study, we have developed a 1-DOF wearable force feedback device with MR brake and pneumatic artificial muscles. These actuators are lightweight, have a high power density, and are controlled by feed-forward control. This device is equipped with the operator's arm and renders various forces, such as friction, elasticity, and viscosity. In this paper, we improve the device to solve existing problems from previous studies. The proposed device is tested to confirm its basic properties. It is applied to augmented reality space and comparisons of subjective evaluations between virtual objects and actual objects

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We have developed an earthworm-type 25A pipe inspection robot using a pneumatic drive. However, the developed robot had a low locomotion speed. This was due to the fact that the contraction amount of the pneumatic artificial muscle used for driving the actuator of the robot was small. To resolve the problem and increase the amount of movement of the robot, an extension actuator to extend in the axial direction was developed. The developed actuators was tested in an experiment that measured the extension amount. At that time, it was confirmed that the actuator largely extended while bending. Therefore, an experiment was performed to verify the bending of actuators and to confirm the extent of the bending. Test results confirmed that the movement tracing of extension actuator with tension springs on both the inside and outside (actuator2) was straighter than that of extension actuator that used the tension spring only on the inside (actuator1). In addition, the developed actuator was tested in an experiment that measured pushing force and pulling force. It was also verified that the extension actuator satisfied the force requirements for the robot.

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In this paper, permissible resistant torque considering back-drivability is verified to develop a wearable assist suit (WAS). The WAS has a clutch and a variable viscoelasticity joint. In this paper, permissible resistant torque is defined as torque that is acceptable in daily use. As first stage of the WAS development, the paper discusses the relationship between the resistant torque to the knee and the degree of discomfort experienced by the wearer as evaluated through a survey questionnaire experiment. In addition, the influence of the resistant torque on a muscle of the knee extension is considered and confirmed by measuring surface electromyography (surface-EMG).

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To reduce the risk of serious accidents, such as road subsidence caused by damaged and aging sewer pipes, internal inspections of sewer pipes is required. However, it is difficult to inspect small diameter pipes using existing inspection devices. In order to solve this challenge, this paper focuses on the locomotion of an earthworm that is capable of moving stably in a narrow space. A peristaltic crawling robot was developed which was capable of traveling 100 m through a 100A specification pipe using a peristaltic movement. The robot consists of a seven unit section, six joints, and a head unit equipped with a camera. It is actuated with the use of an artificial muscle operated by air pressure. The effectiveness of the new robot was evaluated by conducting experiments in horizontal, vertical, and bent pipes. In addition, the authors proposed and validated a new movement pattern to increase the robot speed in 90 degrees elbow pipes.

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Bipedal robots capable of various dynamic motions such as walking, running, and jumping have been developed in recent years. In particular, these dynamic motions require the use of high power in a short time when the robot kicks off the ground. Furthermore, it is necessary to decrease the impact force that a robot is subjected to when landing during these motions. Unfortunately, rigid actuators tend to become heavier as their output increases. Therefore, we focus on the method for obtaining a high output using elastic energy. However, the use of the elastic element only leads to robot vibration. Therefore, to control the dynamic motion, we adopted the viscosity element to the robot joint. In this study, we focused on a straight-fiber-type artificial muscle for the elastic element and a magneto rheological brake for the viscosity and friction elements, respectively. A previously designed monopedal robot was able to jump 82.5 mm using a sliding rail and counter weights; however, the robot shook upon landing because of the presence of the elastic element in its artificial muscles. In this paper, we first proposed a dynamic model of the previously developed monopedal robot. We then performed vertical jumping simulations of the robot to confirm the model's utility.

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In this study, a variable viscoelastic joint system with a clutch for a human assistance was proposed. The variable viscoelastic joint system comprised antagonized artificial muscles and magneto-rheological fluid brake (MR-brake). This system enabled the human assisting device such as exoskeletons to retain structural softness when compared with the existing devices driven by motor and reduction gear, which could only achieve superficial softness. In addition, a clutch system that provided high back-drivability to the wearer by structurally separating the device from the wearer was proposed. As an initial step in designing the human assisting device, a prototype with the proposed variable viscoelastic joint system for knee assistance is developed. Also, its control method were developed. Furthermore, experiments were conducted to confirm the influence of the proposed viscoelastic joint system on the wearer and the effectiveness of the clutch system.

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Lower back pain continues to be an issue worldwide. One cause of lower back pain is the burden on the lumbar region caused by the handling of heavy objects. To reduce this burden on the lumbar region in the lifting, the Ministry of Health, Labour and Welfare in Japan has recommended a lifting technique called "squat lifting." However this technique, which supports a large force on the knee, is not very popular. Therefore, to spread the use of squat lifting, we aimed to develop a power assist suit for knee auxiliary. In this study, firstly, the validity of the squat lifting in lower back pain was measured. Next, to construct a prototype based on the target value, the knee joint moments from motion analysis of squat lifting was estimated. Finally, the prototype was mounted on a human body to evaluate its performance. And we confirmed the effectiveness of the prototype.

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This paper focuses on control of variable viscoelasticity joint manipulator. Each joint consists of pneumatic rubber artificial muscle and magnetorheological fluid. And the joint can generate instantaneous force by accumulating potential energy in artificial muscle. Using instantaneous force appropriately, robots can perform dynamic motion such as jumping and throwing like a human. These motions are expected to contribute to the efficient transport of objects and improve the robot's mobility. And also, elasticity and viscosity of joints are needed to control appropriately to achieve target task. Therefore, we proposed a method to control variable viscoelasticity of joint. We set throwing motion as a target task. And elasticity and viscosity are decided by simulation. In addition, simulation result is optimized by Particle Swarm Optimization (PSO) algorithm. Finally, we conducted throwing experiment to reproduce the simulation result. As a result, simulation result showed that elasticity and viscosity changed to accelerate end effector. However, experimental result showed deviations from simulation result because of model error.

DOI： 10.1007/978-3-319-43506-0_50

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Low back pain of workers is increased in workplaces that involve hard work. It is caused by excessive loading of the waist joint and muscle fatigue. Therefore, power-assist suits have been developed to decrease the load on the waist joint. However, previous power-assist suits have had problems such as low output or heaviness. Thus, we have developed an assist suit that is lightweight and exerts a large force. A balloon actuator and pneumatic artificial muscles are attached to assist suit as the actuators. The assist suit has various desirable features: lightweight, flexibility, and high output. First, human motion is analyzed for the development of the assist suit. The assist suit is developed to assist the waist joint torque. The assist suit is modeled, and the theoretical values of its generation force are estimated using an assist-suit model. Finally, the assist suit is evaluated by measuring the surface electromyography (EMG). The EMG of the wearer is compared with that without the suit. The effectiveness of the assist suit is confirmed by a decrease in EMG.

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At present, city infrastructures are supported by buried gas pipes. Recently, to prevent gas leakage from old gas pipes (which can lead to accidents), routine inspections are required. However, current inspection methods require enormous cost and time. To solve this problem, researchers have developed various pipe inspection robots; however, these robots have difficulty climbing or maneuvering through narrow pipes. Therefore, we focused on the peristaltic crawling of an earthworm. This motion provides a large contact surface area in small spaces, enabling movement through narrow pipes. Therefore we developed a peristaltic crawling robot. It is installed with a straight-fiber-type artificial muscle and is driven by a fire-safe pneumatic system. However, delaying air transmission reduces the velocity of the robot. Considering the costs of hiring workers and the problems created by incidents such as roadblocks, a short inspection time is desired. Installing a solenoid to increase the robot's velocity is impractical in gas pipes because it increases the fire risk. Therefore, we propose an air discharge hole on-off mechanism and instant-supply high pressure and confirm their efficacy in the present study.

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Recently, force feedback devices that intuitively achieve excellent operation have attracted attention in a wide range of fields such as remote operation, virtual reality, and medical training systems. However, it is difficult for conventional devices to widely display soft and hard objects because of driving motors. Moreover, they are likely to be hazardous in the event of delayed response to an unexpected external force. To solve these problems, we previously developed a force feedback device using pneumatic artificial muscles, which are structurally flexible and have wide a range of stiffness, and magneto rheological clutches. Furthermore, we confirmed that any three-dimensional virtual object can be displayed using the developed device. However, when the operation part of the force feedback device is moved away from the virtual object, it remains stuck to the virtual object. In this study, we propose a system to reduce the sticking phenomenon and experimentally confirm the reduction rate (85%). Moreover, we displayed viscous torque as a new application of the feedback device.

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We have been developing an excavation robot for lunar subsurface investigations. The robot locomotion is based on the peristaltic crawling of an earthworm, which enables stable movement. The robot comprises three units: propulsion, excavation, and discharging units. In our previous research, we demonstrated that the propulsion and excavation units can excavate down to 650 mm without the discharging unit. However, when all three units were incorporated into the robot, excavation was limited by soil dropping from the discharging unit. To overcome this problem, we developed a novel soil circulating system. This paper presents the new system and experimentally verifies its feasibility. Finally, the contribution of the proposed system is confirmed in an excavation experiment. The robot's performance was remarkably improved by the system, and its excavation depth increased to 938 mm.

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Lower back pain accounts for more than half of all reported on-the-job ailments, escalating from a personal challenge to a broader societal challenge. Researchers have developed a power assist suit intended prototype to reduce the incidence of lower back pain in the workplace when process automation is not possible. Equipped with two pneumatic actuators, the prototype suit is lightweight, flexible, and efficient. The prototype suit can assist human motion using passive and active forces. In this study, researchers confirmed the effectiveness of passive assistive force. Two types of motion were considered: lifting and unloading in a crouching position and carrying. Researchers first analyzed the subject motions using video analysis software. Waist joint loads were estimated using motion analysis results and a human link model. Second, researchers determined the power assist suit's operational parameters and developed a power assist suit model. Lastly, researchers confirmed the passive force prototype suit's effectiveness based on measured changes in generated force and electromyography.

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Sub-seafloor explorations are important for biological and geological research. Sampling mud is one of the major sub-seafloor exploration procedures. The mud-including mineral resources and marine sediments are potentially valuable resources for future studies. Therefore, we propose a peristaltic-crawling-based sub-seafloor excavation robot for deep sea exploration. This robot consists of three units (propulsion, excavation and extraction units), enabling it to move freely through mud. The excavation and propulsion units are fitted with an earth auger and artificial muscles, respectively. In this paper, we verify the propulsion actuator as the first stage of robot development. First, we evaluate the performance of an oil hydraulic artificial muscle under water pressure. Next, we develop an excavation robot by incorporating a pneumatic artificial muscle into a robot and then experimentally evaluate propulsion and excavation of the robot. We confirmed that the artificial muscle appropriately performs as an actuator for the excavation robot.

DOI： 10.1109/IROS.2015.7353921

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

In recent years, accidents wherein roads have collapsed because of aging sewer pipes have been widely reported. To prevent such accidents it is necessary to inspect sewer pipes. We have developed a sewer pipe inspection robot inspired by peristalsis, the method that earthworms use to move. This robot comprises seven units, six joints, and a head part with a camera for inspection. In this study, we conducted field tests using actual sewer pipes, and confirmed the functioning, usefulness and potential of the robot.

DOI： 10.1299/jsmeicam.2015.6.82

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

Lower back pain has become a serious problem in many workplaces. It is caused by lifting of heavy objects and adopting bad postures such as crouching. We have developed a power-assist suit that effectively eases the lifting-up motion. In this study, we evaluate the effectiveness of the assist suit in crouching positions. To this end, we selected two motion patterns of the assist suit and verified their effectiveness using a force sensor, motion analysis, and electromyography.

DOI： 10.1299/jsmeicam.2015.6.60

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In recent years, the demand for rocket launching has increased due to the development of space technology. However, using inexpensive rockets is not always possible. Although the cost of solid-propellant rockets is relatively reasonable, safely manufacturing a large amount of solid propellant is difficult, and the manufacturing process is disjointed. Therefore, safe and continues manufacturing of solid propellant is necessary. On the basis of the movements of the intestinal tract, we realized that the movements required for transport and mixing of solid propellants are possible to achieve without the application of a large force. By mimicking these intestinal movements, we can safely and continuously manufacture a large amount of solid propellant. We developed a peristaltic pump, based on bowel peristalsis, using straight-fiber-type artificial muscle, and in this study, we demonstrate the usefulness of this pump for transporting the highly viscous fluids and solid-liquid mixed fluid. We consider that the peristaltic pump can also be effectively used as a mixing device. In this paper, we show that mixing one highly viscous fluid with another is possible by measuring the luminance values. In the manufacturing process, we use glass beads with the same diameter as microparticles and a sodium polyacrylate aqueous solution resembling a high viscosity fluid or hydroxyl-terminated polybutadiene as the raw material in the solid propellant. We then measure the glass beads in the resulting solid-liquid mixed fluid.

DOI： 10.1109/IROS.2015.7353920

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

Recently, improvement in robots with human affinity is necessary. This improvement can be achieved by designing a telescopic actuator comparable to that of a human muscle cell. We study a shape memory alloy (SMA) actuator protected by a rolled film tube. In the present study, the actuator is inserted into a natural rubber tube and investigated the characteristics.

DOI： 10.1299/jsmeicam.2015.6.121

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Ladders are used in various places and for a variety of applications because ladders do not need to be installed in large spaces or specific structures. However, humans carrying heavy loads when using a ladder are subject to fatigue and the risk of falling. In this study, we proposed a robot that is capable of climbing various types of ladders using a simple link mechanism.

DOI： 10.1299/jsmeicam.2015.6.72

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This study describes the development of an omni-directional wall climbing robot with permanent magnets for the purpose of inspecting the walls of ships and gas tanks. The robot travels omnidirectionally and achieves stable movement through its large contact area. We equipped our traveling-wave-type omni-directional robot with a permanent magnetic adhesion mechanism and confirmed its wall-climbing ability. In this study, we analyze the magnetic field of the permanent magnetic adhesion mechanism by using finite element method. An improvement of the permanent magnetic adhesion mechanism based on the results of the analysis is foreseen.

DOI： 10.1299/jsmeicam.2015.6.241

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We have been developing a lunar subsurface excavation robot using peristaltic crawling based on an earthworm's locomotion. The robot is designed to discharge the excavated soil from the borehole to the ground surface. However, the soil-discharging process is not yet automated. This paper develops and tests two promising soil-discharging mechanisms for automatic soil discharge.

DOI： 10.1299/jsmeicam.2015.6.183

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We developed a one-legged robot with straight fiber-type artificial muscles and a magnetorheological brake for jumping. In this study, we produced a one-legged robot with 2-DOF, structured the jumping model considering landing and calculated the jumping height by simulation. The result of the simulation shows that the robot was able to jump safely.

DOI： 10.1299/jsmeicam.2015.6.300

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

A wearable force feedback device enables us to dynamically interact with a virtual object while moving in a wide virtual space. We have developed a wearable force feedback device with a pneumatic artificial muscle and a magnetorheological (MR) brake. These mechanical elements show quick response by feed-forward control and have high power density. In this paper, we tackled on weight saving of the device, and measured basic property again. Afterward, we evaluated whether operators could perceive the difference when rendered different magnitudes of frictional force or elastic force. The operators were rendered one of the five levels of force, and replied which level this force was.

DOI： 10.1299/jsmeicam.2015.6.243

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Desktop haptic device has been developed in the field of rehabilitation and entertainment. However, the desktop type restrains human's movement. Therefore, it is difficult to receive force sense information, moving to wide range position and posture. In this study, we developed a 1-DOF wearable haptic device with pneumatic artificial muscles and a MR brake. These smart actuators have high power density and change its output force structurally. Therefore, this haptic device can render various force sense such as elasticity, friction and viscosity. In this abstract, we describe two experiments rendering elasticity and friction to evaluate the performance of the device.

DOI： 10.1109/VR.2015.7223351

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Authorship：Last author,　Corresponding author   Language：English   Publisher：The Society of Instrument and Control Engineers  

This paper describes the development of an in-pipe inspection robot for use in half-inch pipes. Half-inch pipes are commonly used in factories and residences, and in-pipe inspection is essential for preventing accidents caused by burst pipes or corrosion. In-pipe inspection is currently endoscopically conducted; however, endoscopes cannot be inserted into pipes that are more than 15m long or that have complex shapes, such as elbows. Therefore, various in-pipe inspection robots have been developed, though very few can travel inside half-inch pipes, and none can pass through a 90° elbow. Moreover, no study reports in-pipe robots making long-distance runs within half-inch pipes. The authors have developed a peristaltic crawling inspection robot with pneumatic artificial muscles for use in half-inch pipes; they seek to enable the robot to pass through a 90° elbow and have studied the robot's ability to travel long distances of more than 15m.

DOI： 10.9746/jcmsi.8.256

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This study aims to develop a new type of peristaltic pump that transports high-viscosity and solid-liquid mixture fluids. Pumps capable of transporting such fluids are essential in various situations such as factory transportation, outdoors, and emergencies. These fluids are conventionally transported by positive-displacement and rotodynamic pumps. However, solid-liquid fluids could collide with the impeller of the rotodynamic pump and thereby damage the pump, whereas the positive-displacement pump must be sufficiently large to apply high pressure to the transported fluid. A small pump that can transport these fluids would save factory space and enable outdoor applications such as dredging operations. Thus, we adopted earthworm peristalsis as a model mechanism of fluid transport within a standard plumbing infrastructure. The insertion-type peristaltic pump developed in this study uses an artificial rubber muscle to achieve an earthworm-like mechanism. The capability and energy efficiency of the mechanism is evaluated in water transportation experiments.

DOI： 10.1080/01691864.2015.1052847

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Recently, planetary investigations have accumulated basic data through various aerospace explorations. However, the investigations of underground such as moonquakes, heat, and conditions of the soil have not revealed much. Therefore, the authors have developed a novel, small planetary subsurface excavation robot that uses the peristaltic crawling of an earthworm as its underground propulsion method. In this study, the authors focused on two types of geotechnical tests: pressure meter and shearing tests using the excavation robot. These tests were conducted by measuring displacement and force in the radial and vertical directions inside the soil, using the excavation robot's own hardware system. This paper describes these geotechnical tests, which used the propulsion unit of the robot and measured the soil parameters, e.g., internal friction angle, adhesibility, and elastic constant. From the experiments, the authors evaluated and discussed results by comparing with reference data. The authors confirmed that the propulsion unit could measure the soil parameters and propel itself underground at the same time.

DOI： 10.9746/jcmsi.8.242

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Humans perform various motion such as jumping or throwing without high vibration, via variable viscoelasticity characteristics. On the other hand, highly rigid actuators such as geared motors or hydraulic actuators are widely used in industrial robots. It is difficult that they have variable viscoelasticity for them. In addition, to obtain high-speed motion, it is necessary to increase the actuator output as the robot weight increases. We have developed a one-degree-of-freedom manipulator with a variable rheological joint using a straight-fiber-type artificial muscle and a magnetorheological (MR) brake. With the generation of instantaneous force, the dead and rise times decreased compared to the conventional method. After the generation of an arbitrary instantaneous force, we controlled the robot's arm position by applying an equilibrium force on the joint. Furthermore, we controlled the vibrations of the arm by controlling the MR brake using an evaluation function. By this impedance control, response of the arm was improved without large loss of power.

DOI： 10.9746/sicetr.51.380

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Society of Instrument and Control Engineers  

This paper describes a development of an colonoscopic device that veering-out a latex tube with jamming by granular materials and an application to a large intestine of dead swine. Recently, colorectal cancer is increasing. However, the cancer can be cured completely if it is discovered and treated early with a large intestine endoscope. A conventional endoscope can screen and heal the inside of the intestine, but such surgery is difficult for doctors. In this study, in order an attempt to solve these problems, we propose an endoscopic device that veering-out a latex tube with jamming by granular materials. This device can pass through the sigmoid colon of dead swine that is set like a human without difficult operation. Unlike other endoscopic robots, our device can support the endoscope. Thus we can easily perform various functions of the conventional endoscope. Here we explain our device using rice as jamming material. Next, we describe our experiment confirming the efficacy in large intestine model. We also confirm the availability of the endoscopic support device for use in the large intestine of a dead swine.

DOI： 10.9746/sicetr.51.290

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Authorship：Last author,　Corresponding author   Language：Japanese   Publisher：The Society of Instrument and Control Engineers  

We have developed the traveling wave type omni-directional mobile robot that imitates the snail locomotion mechanism. An advantage of this movement mechanism is that it enables stable motion because of a large contact area. We think that this stable motion is applicable to wall climbing. In this paper, we developed magnetic adhesion mechanism that can be switched adhesion and installed it in the robot. Furthermore, we confirmed the performance of this robot through experiments.

DOI： 10.9746/sicetr.51.282

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

This paper describes a proposal for a locomotion strategy for an omnidirectional wall-climbing robot for spherical surfaces. This robot was developed for inspecting the walls of ships and gas tanks, which require regular inspection. Because such walls are ferromagnetic, many other wall-climbing robots have been developed. However, the stable movement of such robots is prevented by their small contact area. Conversely, we have developed a travelling-wave-type omnidirectional mobile robot that uses the locomotion mechanism of a snail. This robot travels omnidirectionally and achieves stable movement through its large contact area. Previously, we equipped our traveling-wave-type omnidirectional robot with a permanent magnetic adhesion mechanism and confirmed its wall-climbing ability. Moreover, we installed universal joints to allow this robot to adjust to curved surfaces. In this paper, we model the robot in 3-dimensional space and suggest an omnidirectional locomotion method for spherical surfaces. Through simulation, we verify the availability of locomotion strategy.

DOI： 10.1109/ROBIO.2015.7419104

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG BERLIN  

We developed an earthworm-type 15A pipe inspection robot with pneumatic artificial muscles (PAMs). The movement of the robot is performed by a drive unit that repeatedly expands and contracts the muscle. Pressurized air is supplied to the muscle via an air tube. The robot is required to change the specifications of the tube in accordance with the distance of inspection. When the specifications change, the responses of air transmission and the drive unit also change. To date, the optimum operating condition of the drive unit has been obtained experimentally, but this is an extremely time-consuming problem. Thus, we derive a dynamic characteristic model of the PAMs that considers the length of the air tube. Then, the usefulness of the model is confirmed by comparing its results to experimental values of the artificial muscle.

DOI： 10.1007/978-3-319-22879-2_36

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：EMERALD GROUP PUBLISHING LIMITED  

Purpose - This paper aims to develop a wave-transmitting mechanism for a travelling-wave-type omnidirectional mobile robot. Existing omnidirectional mechanisms are prone to movement instability because they establish a small contact area with the ground. The authors have developed a novel omnidirectional mobile robot that achieves stable movement by a large ground-contact area. The proposed robot moves by a wave-transmitting mechanism designed for this purpose.
Design/methodology/approach - To achieve stable movement, a spiral-type travelling-wave-propagation mechanism that mimics the locomotion mechanism of a snail was developed. The mechanism was applied to an omnidirectional mobile robot.
Findings - The practicality of magnetic attraction was verified in experiments of the wave-transmitting mechanism. Moreover, omnidirectional movement was confirmed in a robot prototype adopting this mechanism.
Research limitations/implications - The proposed robot will eventually be deployed in human spaces such as factories and hospitals. A mechanically improved version of the robot will be evaluated in load-driving experiments and equipped with control systems.
Originality/value - This paper proposes an omnidirectional mobile robot with a large ground contact area that moves by continuous travelling waves. The practicability of this mechanism was experimentally confirmed, and a prototype robot achieved omnidirectional movement.

DOI： 10.1108/IR-10-2014-0401

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

The performance of a robot can be enhanced by increasing its output. However, increasing the output of rigid actuators such as motors and hydraulic actuators will likely increase the weight of the robot. Conversely, organisms such as human beings achieve high output within a short time by accumulating and releasing the elastic energy stored in their muscles (thus providing an instantaneous force). Moreover, the viscoelastic properties of muscle enable organisms to control their instantaneous force outputs and their overall movements. Therefore, in this study, we developed a manipulator with a 2-degree-of-freedom (DOF) variable viscoelastic joint. The manipulator comprises a straight-fiber-type artificial muscle and a magnetorheological (MR) brake. The ability of the manipulator to generate controlled movement from an instantaneous force was tested in a throwing operation. This simple 2-DOF variable viscoelastic manipulator with apparent viscosity control by the MR brakes achieved successful throwing motions.

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Language：English   Publisher：The Japan Society of Mechanical Engineers  

We have been developing a lunar subsurface excavation robot using peristaltic crawling based on an earthworm&#039;s locomotion. In existing robots, the excavated soil must be manually removed by humans. To overcome this limitation, we have been developing a mechanism that automatically removes the excavated soil. This paper presents our new automatic soil-release mechanism and demonstrates the performance of the mechanism using a prototype.

DOI： 10.1299/jsmeicam.2015.6.298

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Lifting heavy objects increases the risk of low back pain. In this study, we calculate the load exerted on the human body during an actual lifting operation. To assist lifting, we propose an endoskeleton-like suit that exerts an assistive force. A prototype of the assist suit is developed in this study. The force is exerted by a straight-fiber-type artificial muscle combined with an amplification mechanism. The notion of assistive force was subjectively evaluated by wearers, and confirmed in on a visual analogue scale. The electromyography signals of wearers were decreased, confirming the subjective assist effect.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG BERLIN  

Force feedback devices have been recently adopted in virtual reality, rehabilitation, and medical training systems. Many of these devices convey the human forces sensed by the impedance control using motors; however, motorized actuators are disadvantaged by low output and backdrivability. To resolve these disadvantages, we developed a delta-type parallel-link robot using pneumatic artificial muscles and magnetorheological (MR) clutches. The artificial muscles deliver high output and backdrivability, while the MR clutches enable fast responses. Moreover, because the stiffness of its pneumatic artificial muscles directly responds to forces, our robot detects human forces without feedback from force sensors. This study introduces the prototype of our delta-type parallel-link robot, and evaluates its performance in elastic movement experiment. Finally, we confirmed that our prototype robot can obtain the stiffness and unloaded condition through its MR clutches without feedback from force sensors.

DOI： 10.1007/978-3-319-22879-2_38

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Bipedal robots capable of various dynamic motions such as walking, running, and jumping have been developed in recent years. In particular, these dynamic motions require high power for short durations of time when the robot kicks off the ground. Furthermore, it is necessary to reduce the impact force that a robot is subjected to when landing during these motions. When humans perform similar motions, they generate an instantaneous high-power force using an elastic element and dampen the impact force using a viscous element in their muscles. Therefore, a robotic leg designed for jumping that relies on these elements has been developed. It uses a straight fiber-type artificial muscle and a magnetorheological (MR) brake. A previously designed one-legged robot was able to jump 82.5 mm using a sliding rail and counter weights; however, it shook upon landing due to an elastic element in its artificial muscles. Here, therefore, an MR brake to dissipate energy is applied to the robotic leg in order to suppress vibration. Landing experiments performed with the newly designed one-legged robot confirm that the proposed method (i.e., using the MR brake) is able to suppress vibrations.

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG BERLIN  

In recent years, observations and explorations of the deep seafloor have been actively pursued. One goal of such explorations is to obtain the samples of seafloor mud and its inclusions. Mud that contains minerals and submarine microorganisms has great potential for studies in biology, geology, and marine science. To contribute to these efforts, we propose a robot using peristaltic crawling to excavate deep seafloor. The robot consists of three parts: excavation, propulsion, and extraction units. The propulsion actuator of the proposed robot must be able to function under water at high pressures. As the first stage in the development, we developed a subunit using an oil hydraulic artificial muscle intended for use in deep sea, and conducted a performance experiment under water pressure. Our results confirmed that the artificial muscle can be used in water pressures of up to 5 MPa.

DOI： 10.1007/978-3-319-22879-2_35

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Springer Verlag  

Recently, the use of haptic technology has been expected in various fields, such as medicine and entertainment. In general, haptic devices are actuated by DC motors. However, DC motors have active rendering and can cause serious accidents when the system runs out of control. On the other hand, systems that employ a brake are stable and intrinsically safe. However, such systems have several haptic rendering limitations. Therefore, we have developed a semi-active-type haptic device using variable viscoelastic elements: an electrorheological (ER) devices and pneumatic artificial muscles. In this paper, we proposed control modes according to the haptic application, and we demonstrate several haptic experiments. Finally, we confirm that the novel semi-active system achieves haptic rendering of friction, viscous friction, virtual wall, and stiffness.

DOI： 10.1007/978-3-319-22879-2_39

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Corresponding author   Language：English   Publisher：FUJI TECHNOLOGY PRESS LTD  

We have developed a small, unmanned explorer robot to investigate the undergrounds of satellites and planets. This paper describes the developed excavation robot, which is based on earthworm locomotion. The robot demonstrates excavation activity at 1/6 of its own weight, mimicking the light gravity conditions of the Moon. We conclude that the robot is suitable for future excavation missions.

DOI： 10.20965/jrm.2014.p0660

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Corresponding author   Language：Japanese  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

We have developed a robot that can inspect long distances in thin sewer pipes. Inspections of sewer pipes are necessary to prevent accidents such as road caving accidents. However, thin sewer pipes cannot be easily inspected by existing methods. To solve this problem, we developed a peristaltic crawling robot that mimics earthworm locomotion. This robot comprises six units: five joint parts and a head part with a camera that inspects inside the sewer pipes. As the actuator in the unit is a pneumatic artificial muscle, the robot is driven by air pressure. Air is supplied to each unit through an electric valve mounted directly on the unit, thereby preventing delay in air transfer. We confirmed that the robot can stably drive through horizontal and vertical sewer pipes. In driving tests through a bending pipe, we identified materials for the joint parts that enable the robot to smoothly travel through the pipe. During these tests, we further evaluated the robot's traveling performance by measuring its driving speed through the pipe. © 2014 IEEE.

DOI： 10.1109/AIM.2014.6878304

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

The purpose of this study is to evaluate the energy efficiency of an insertion-type peristalsis pump and compare it with conventional methods such as the positive-displacement pump and rotodynamic pump. This device can transport high-viscosity fluids and solid-liquid-mixture fluids with low applied pressure in small spaces and various places such as the outdoors. In previous studies, the authors showed that this pump can transport water through a vertical pipe and a bent pipe. However, the performance of this devise has not been compared with that of conventional pumps. Thus, this paper evaluates the efficiency of the insertion-type peristalsis pump and has demonstrated that the insertion-type peristalsis pump has excellent energy efficiency.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Recently, many omnidirectional mobile robots have been developed, which require omnidirectional mobile mechanisms to allow them to move within narrow, complicated passages. However, existing omnidirectional mobile mechanisms cannot achieve stable movement because of their small contact areas. In this paper, we propose an omnidirectional mobile robot that achieves stable movement through a spiral-type traveling-wave-propagation mechanism based on a snail's locomotion mechanism. To demonstrate the robot's performance, we conducted a driving experiment using a prototype.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Recently, research of a haptic device that renders human arbitrary-force sense has been accelerating for application in rehabilitation and virtual reality/augmented reality devices. Generally, these devices are actuated by electric motors
however, the actuators have low stiffness output and low backdrivability. In an effort to counteract these drawbacks, we developed a delta robot actuated by straight-fiber-type pneumatic artificial muscles. This robot renders human arbitrary-force sense without force sensor feedback. Furthermore, this robot has backdrivability derived from the softness of the pneumatic artificial muscles and no backlash because the structure does not use gears. Thus, by adopting a delta mechanism as a haptic device, high stiffness output and low inertia force are realized. In this study, we introduce the development of the delta robot as the prototype of a haptic device and conduct position-control and stiffness-control experiments to examine the device's fundamental properties. From the experimental results, we confirm that end position is controllable by both sides of static and dynamic state, and the stiffness of the end plate is controllable without feedback of the force sensor. © 2014 IEEE.

DOI： 10.1109/AIM.2014.6878278

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper describes the development of an omnidirectional wall climbing robot with permanent magnets for inspecting the walls of ships and gas tanks. These features require regular inspection, which is costly and exposes workers to risk. Because such walls are ferromagnetic, they can be monitored by robots with permanent magnets, and many wall-climbing robots have been developed. However, stable movement of such robots is prevented by their small contact area. Previously, we have developed a traveling wave type omnidirectional mobile robot that uses the locomotion mechanism of a snail. This robot travels omnidirectionally and achieves stable movement through its large contact area. We expect that this locomotion mechanism is suitable for wall climbing. In this paper, we have equipped our traveling wave type omnidirectional robot with a permanent magnetic adhesion mechanism, enabling it to climb walls. In locomotion experiments, we confirm that the robot can move omnidirectionally on a horizontal surface (0 degrees), a wall (90 degrees), and a ceiling (180 degrees).

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

As the aged population increases, increasing numbers of people require walking support as the strength of their leg muscles deteriorates. We have developed a flexible power walking assistant system based on pneumatic artificial muscle. To date, the walking assistance effect of this approach has been validated in experiments, but few subjects were recruited. In the present study, we have incorporated pneumatic rubber artificial muscle into a new mechanism, enabling smaller and lighter weight devices for walking assistance. Unlike conventional mechanisms of this type, which require separate artificial muscles for each foot, our proposed mechanism assists both feet by a single artificial muscle. A prototype model of our proposed new mechanism was applied to artificial muscles, and its practicality was evaluated in operational experiments. © 2014 IEEE.

DOI： 10.1109/AIM.2014.6878293

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

Exploration below the lunar surface has great potential for scientific progress and the future of space explanation. However, as of now, little is known about the environment of the lunar subsurface, but the international space community has plans to explore it. The development of an excavator that can perform underground investigations has been needed, so we have developed one with a peristaltic crawling mechanism. The robot consists of propulsion and excavation units. The propulsion unit consists of three propulsion subunits which together form the peristaltic crawling mechanism. The excavation unit has an earth auger to dig up and transport soil. In this study, we propose a new type of propulsion subunit. It has a belt drive system to facilitate the smooth movement of the propulsion subunits, and it enables the robot to support three subunits. We also perform experiments in which the excavation robot burrows into red soil to depths of up to 600 mm.

DOI： 10.20965/jrm.2013.p0466

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