| 1. |
Toshihiko Fukushima, Satoshi Nishikawa, Yasuo Kuniyoshi, Active pole bending effect in pole support phase., Sports biomechanics, 10.1080/14763141.2022.2129087, 1-17, 2022.10, In pole vaulting, model analysis is one of the key methods to increase vaulting height. To date, the effects of athletes' motions during 'pole support phase' have been measured and modelled to improve and set new world records. The motions were extracted based on the context of pole bending interaction and parameters to improve vaulting height were investigated. However, due to experimental, mechanical, and sensing restrictions, ranges and interactions of the parameters were poorly addressed. To investigate further, a parameter space must be globally explored. Here, we show parameter sensitivities and interactive effects between initial velocity, pole length, bending amplitude and switching time. From the simulation studies, we found that active pole bending enabled successful pole vaulting with lower initial velocity and longer poles. Vaulting height had a local maximum point at a specific initial velocity and positive bending could control conditions to deliver the local maximum height. Positive bending controls the rising-up speed of the pole and contributes to the verticalisation of the vaulting angle. Negative bending increases the vaulting speed and contributes to the robustness of the vaulting angle. Our results demonstrate how these parameters affect the vaulting performances and suggest how athletes should activate their bodies.. |
| 2. |
Satoshi Nishikawa, Daigo Tokunaga, Kazuo Kiguchi, Adjustable Lever Mechanism with Double Parallel Link Platforms for Robotic Limbs, IEEE International Conference on Intelligent Robots and Systems, 10.1109/IROS47612.2022.9981521, 2022-October, 1950-1956, 2022.10, For universal robotic limbs, having a large workspace with high stiffness and adjustable output properties is important to adapt to various situations. A combination of parallel mechanisms that can change output characteristics is promising to meet these demands. As such, we propose a lever mechanism with double parallel link platforms. This mechanism is composed of a lever mechanism with the effort point and the pivot point; each is supported by a parallel link mechanism. First, we calculated the differential kinematics of this mechanism. Next, we investigated the workspace of the mechanism. The proposed mechanism can reach nearer positions than the posture with the most shrinking actuators thanks to the three-dimensional movable effort point. Then, we confirmed that this mechanism could change the output force profile at the end-effector by changing the lever ratio. The main change is the directional change of the maximum output force. The change range is larger when the squatting depth is larger. The changing tendency of the shape of the maximum output force profile by the position of the pivot plate depends on the force balance of the actuators. These analytical results show the potential of the proposed mechanism and would aid in the design of this mechanism for robotic limbs.. |
| 3. |
Daigo Tokunaga, Satoshi Nishikawa, Kazuo Kiguchi, Motor power distribution mechanism for simultaneous independent control of multiple cable tensions for humanoid robot hand, JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE), A1-2-01, 2022.08. |
| 4. |
Kanta Maemura, Satoshi Nishikawa, Kazuo Kiguchi, A Study on Artificial Kinesthesia Generation by Simultaneous Stimulation of Mechanical Vibration and Mechanical Skin Stretch, IEEE International Conference on Rehabilitation Robotics, 10.1109/ICORR55369.2022.9896609, 2022-July, 1-6, 2022.07, Artificially controlled kinesthesia can be applied to many situations because kinesthesia is essential to recognizing body movements. It could be used to generate artificial kinesthesia in rehabilitation or daily motion assist to improve self-efficacy of the robot user. Moreover, the controlled artificial kinesthesia could make people feel as if they are performing the actions of the robotic limbs with their own limbs. Mechanical vibration stimulation is one of the candidates to artificially control kinesthesia. It is known that mechanical vibration stimulation on human muscles or tendons from skin surface evokes an illusion of movement as if the stimulated muscles are extended. That effect of artificial kinesthesia is called Kinesthetic Illusion (KI). In this paper, a method to increase the amount of KI without changing the frequency of the vibration stimulation is investigated by applying mechanical skin stretch stimulation at the same time with the mechanical vibration stimulation. The experiment was conducted by generating KI for flexion motion of the elbow joint on a horizontal plane to evaluate the proposed approach. In the experiments, three out of five subjects showed obvious increase in the amount of KI when skin stretch stimulation was applied at the same time with the mechanical vibration stimulation. The results of this study provide a first step toward artificial kinesthesia control using a wearable robotic device using the mechanical vibration stimulation.. |
| 5. |
Yue Hou, Satoshi Nishikawa, Kazuo Kiguchi, Real-time Estimation of Human Reaching Motion for Human Assist Robots, 32nd 2021 International Symposium on Micro-NanoMechatronics and Human Science (From Micro & Nano Scale Systems to Robotics & Mechatronics Systems) (MHS2021), 2021.12. |
| 6. |
Danwen Li, Satoshi Nishikawa, Kazuo Kiguchi, Control of ankle joint motion change induced by vibration stimulation on the Gastrocnemius muscle during continuous joint motion, International Conference on Control, Automation and Systems, 10.23919/ICCAS52745.2021.9649798, 2021-October, 1766-1771, 2021.10, It has been shown that changes in movement caused by reflex phenomena and kinesthetic illusion can be induced by giving vibratory stimulation on specific muscles during limb movements. By using this phenomenon, there is a possibility that the lower-limb perception-assist, in which inappropriate motion is automatically modified, is realized. In this study, change of ankle joint motion by giving the vibration stimulation on the gastrocnemius muscle in the lower-limb is studied by performing the experiment of adding vibration stimulation to the gastrocnemius muscle during the movement of ankle joint dorsiflexion and plantar flexion under several frequency ranges. The results indicate that the amount of motion change varies depending on the frequency of the vibration stimulation. Based on the characteristics of motion change with respect to vibration stimulation, a method to control the change of the user's ankle joint dorsiflexion motion by adjusting the frequency of the vibration stimulation to achieve the target motion, which is different from the user's intended motion, is evaluated. It is confirmed that there is a possibility that the vibration stimulation can be applicable to modify the human ankle joint motion for the perception-assist using frequency change.. |
| 7. |
Satoshi Nakagawa, Shogo Yonekura, Hoshinori Kanazawa, Satoshi Nishikawa, Yasuo Kuniyoshi, New Approach to Estimating Mental Health Score Using a Communication Agent, Advances in Intelligent Systems and Computing, 10.1007/978-3-030-73113-7_24, 1357, 239-247, 2021.07. |
| 8. |
Satoshi Nakagawa, Shogo Yonekura, Hoshinori Kanazawa, Satoshi Nishikawa, Yasuo Kuniyoshi, Estimation of Mental Health Quality of Life using Visual Information during Interaction with a Communication Agent, 29th IEEE International Conference on Robot and Human Interactive Communication, RO-MAN 2020, 10.1109/RO-MAN47096.2020.9223606, 1321-1327, 2020.08, It is essential for a monitoring system or a communication robot that interacts with an elderly person to accurately understand the user's state and generate actions based on their condition. To ensure elderly welfare, quality of life (QOL) is a useful indicator for determining human physical suffering and mental and social activities in a comprehensive manner. In this study, we hypothesize that visual information is useful for extracting high-dimensional information on QOL from data collected by an agent while interacting with a person. We propose a QOL estimation method to integrate facial expressions, head fluctuations, and eye movements that can be extracted as visual information during the interaction with the communication agent. Our goal is to implement a multiple feature vectors learning estimator that incorporates convolutional 3D to learn spatiotemporal features. However, there is no database required for QOL estimation. Therefore, we implement a free communication agent and construct our database based on information collected through interpersonal experiments using the agent. To verify the proposed method, we focus on the estimation of the mental health QOL scale, which is the most difficult to estimate among the eight scales that compose QOL based on a previous study. We compare the four estimation accuracies: single-modal learning using each of the three features, i.e., facial expressions, head fluctuations, and eye movements and multiple feature vectors learning integrating all the three features. The experimental results show that multiple feature vectors learning has fewer estimation errors than all the other single-modal learning, which uses each feature separately. The experimental results for evaluating the difference between the estimated QOL score by the proposed method and the actual QOL score calculated by the conventional method also show that the average error is less than 10 points and, thus, the proposed system can estimate the QOL score. Thus, it is clear that the proposed new approach for estimating human conditions can improve the quality of human-robot interactions and personalized monitoring.. |
| 9. |
Ken Takaki, Yoshitaka Taguchi, Satoshi Nishikawa, Ryuma Niiyama, Yoshihiro Kawahara, Acoustic Length Sensor for Soft Extensible Pneumatic Actuators with a Frequency Characteristics Model, IEEE Robotics and Automation Letters, 10.1109/LRA.2019.2931273, 4, 4, 4292-4297, 2019.10, In this study, we present a length sensor that can be used for extensible soft pneumatic actuators. Conventional length sensors detect the changes in electrical resistance and capacitance owing to the deformation of the actuator; hence, deterioration and destruction occur when they are used with an actuator that has a large expansion ratio. In addition, their low resolution and linearity makes them unsuitable for use in actuator control. Our proposed sensor comprises only a speaker and a microphone installed at one end of the actuator. We propose a method to deterministically measure the length of a tube by generating a broadband acoustic signal in a tube and measuring the resonance characteristics determined by the shape of the tube. Our experimental results demonstrate that the error in the measurement with our sensor is not more than 4% with a strain up to 200%. Unlike conventional acoustic sensing methods that measure the time of flight by using ultrasound, our proposed method yields accurate results even when the tube is bent. Therefore, the proposed method can be applied to various types of pneumatic actuators.. |
| 10. |
YUKI NAKAMURA, IZUMI KARINO, SHOTARO MORI, KAZUTOSHI TANAKA, SATOSHI NISHIKAWA, RYUMA NIIYAMA, YASUO KUNIYOSHI, CONTROL OF PNEUMATIC CYLINDERS USING ITERATIVE LINEAR QUADRATIC REGULATOR WITH DEEP LOCAL LINEAR DYNAMICS FOR EXPLOSIVE MOTIONS, The 22nd International Conference on Climbing and Walking Robots and Support Technologies for Mobile Machines, 2019.08. |
| 11. |
Haruki Cho, Satoshi Nishikawa, Ryuma Niiyama, Yasuo Kuniyoshi, Dynamic locomotion of quadruped with laterally parallel leaf spring spine, CLAWAR 2019: 22nd International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, 10.13180/clawar.2019.26-28.08.12, 91-98, 2019.08. |
| 12. |
Shih Yin Chang, Satoshi Nishikawa, Masaki Sekino, Hiroshi Onodera, Yasuo Kuniyoshi, A Simulation Study of Light Propagation in the Spinal Cord for Optogenetic Surface Stimulation, Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 10.1109/EMBC.2019.8856874, 2019, 6872-6875, 2019.07, For utilizing optogenetics in neuroscience research, a proper setup is necessary, which delivers sufficient light to target cells and minimizes unexpected side effects caused by light exposure. In this study, we were interested in the area of influence of optical surface stimulation on a spinal cord tissue. We built a 3D spinal cord structure of rat and utilized the Monte-Carlo methods to simulate the light transport in it. We first evaluated light propagation in homogeneous nervous tissue models. For a 10-mW, 470-nm light source, light intensity of 1 mW=mm was detected at depths of 1:14 and 1:77 mm in white and grey matter, respectively. This indicated a narrower spreading pattern of light in the white matter than in the grey matter. Since the grey matter, which contains the somatosensory pathways, is an important target of spinal cord stimulation, we focused on investigating how much light could reach this area in a multi-layered structure. The results showed that when an optical fiber was positioned in the center line of the spinal cord dorsal surface, most of the light energy was absorbed before reaching the grey matter. In contrast, when we put the fiber on a lateral position, 0:8mm away from the central line, relatively sufficient light intensity could be detected deep into the lamina 5 area. The experimental results obtained herein suggest that tissue type and the position of stimulation could greatly affect the area of influence of light stimulation in a 3D spinal cord. It is important to consider the location of the interested neural pathways and plan a proper stimulation site before conducting optogenetic surface stimulation of the spinal cord. 2. |
| 13. |
Taigo Yukisawa, Satoshi Nishikawa, Ryuma Niiyama, Yoshihiro Kawahara, Yasuo Kuniyoshi, Ceiling continuum arm with extensible pneumatic actuators for desktop workspace, 2018 IEEE International Conference on Soft Robotics, RoboSoft 2018, 10.1109/ROBOSOFT.2018.8404919, 196-201, 2018.07, We propose an extensible pneumatic continuum arm that elongates to perform reaching movements and object grasping, and is suspended on the ceiling to prevent interference with human workers in a desktop workspace. The selected actuators with bellows aim to enhance the arm motion capabilities. A single actuator can provide a maximum tension force of 150 N, and the proposed arm has a three-segment structure with a bundle of three actuators per segment. We measured the three-dimensional motion at the arm tip by using an optical motion-capture system. The corresponding results show that the arm can grasp objects with approximate radius of 80 mm and reach any point on the desktop. Furthermore, the maximum elongation ratio is 180%, with length varying between 0.75 m and 2.1 m. Experiments verified that the arm can grasp objects of various sizes and shapes. Moreover, we demonstrate the vertical transportation of objects taking advantage of the arm extensibility. We expect to apply the proposed arm for tasks such as grasping objects, illuminating desktops, and physically interacting with users.. |
| 14. |
Shotaro Mori, Kazutoshi Tanaka, Satoshi Nishikawa, Ryuma Niiyama, Yasuo Kuniyoshi, High-Speed and Lightweight Humanoid Robot Arm for a Skillful Badminton Robot, IEEE Robotics and Automation Letters, 10.1109/LRA.2018.2803207, 3, 3, 1727-1734, 2018.07, Sports, especially badminton, require participants to perform dynamic and skillful motions. Previous robots have had difficulty in performing like a human because of their severe limitations of low operating speed, heavy bodies, and simplistic mechanisms. In this letter, we propose a new robot design that consists of a structure integrated with pneumatic actuators and noninterfering many-degree-of-freedom joints, for the realization of a high-speed and lightweight humanoid robot. We made a four-degree-of-freedom robot arm for badminton, which is an especially dynamic sport, aiming for maximum speed while meeting geometric requirements. The robot swung with a racket-head speed of 21 m/s, which is a value higher than speeds achieved by previous robotic arms. The robot also realized a skillful shot, namely the spin net shot, which cannot be performed by previous badminton robots having simple mechanisms. A pneumatic robot is considered difficult to control, especially in terms of feedback control. We found that the reproducibility of the robot was as fine as 10-40 mm at the racket head for four kinds of strong swings. Using feedforward control, we also conducted an experiment in which the robot hits a flying shuttle, and achieved a high hitting rate of 69.7% for powerful swings. We believe that this research expands the possibilities of the pneumatic robot and is the first step toward developing a skillful humanoid badminton robot.. |
| 15. |
Dwindra Sulistyoutomo, Satoshi Nishikawa, Ryuma Niiyama, Yasuo Kuniyoshi, Sequential Jumping-Stepping Motion on Musculoskeletal Humanoid Robot for Agile Locomotion, 2018 IEEE International Conference on Robotics and Biomimetics, ROBIO 2018, 10.1109/ROBIO.2018.8664787, 2328-2333, 2018.07, Combination of various dynamic motions may lead to better performance of dynamic motion tasks by utilizing the energy transfer between the motions. We have developed a robot capable of doing sequential jumping-stepping motion for agile locomotion. The robot is a musculoskeletal humanoid robot that mimics human skeletal system and muscular system with pneumatic artificial muscles as the actuators. For realizing the motion, we decide muscle control command for each motion referring to the muscle activation pattern of a human. We have conducted experiments for the sequential jumping-stepping motion with our motion strategy on the developed musculoskeletal robot. The results show that the musculoskeletal robot performs faster stepping by performing pre-jumping before a stepping than stepping without pre-jumping. We have also found that proper timing of landing command became crucial for the stepping motion performance.. |
| 16. |
Satoshi Nishikawa, Yusuke Arai, Ryuma Niiyama, Yasuo Kuniyoshi, Coordinated Use of Structure-Integrated Bistable Actuation Modules for Agile Locomotion, IEEE Robotics and Automation Letters, 10.1109/LRA.2018.2794617, 3, 2, 1018-1024, 2018.04, It is difficult to design agile soft-bodied robots owing to their inherent softness. To overcome this problem, we propose a structure-integrated bistable module that uses snap-through buckling for agile motions. First, we confirmed that a 0.05-m-long module was able to jump to 0.13 m high. Through investigation, we found a range of command parameters within which the module jumps consistently. Moreover, we showed that jumping performance had strong relation to the bending amplitude. Next, we induced a robot with two serially connected modules to roll forward and jump over an obstacle. In rolling, the robot became round for quick locomotion. In jumping, we found that buckling in one module induced buckling in the other module. The difference in buckling time between the two modules was shortened from the order of 0.1 s to the order of 0.01 s. This might be effective for error correction or useful for coordinated motions. These results show the effectiveness of the proposed structure-integrated bistable modules for making agile soft-bodied robots, and suggest ways of exploiting them.. |
| 17. |
Kenichi Fujita, Shogo Yonekura, Satoshi Nishikawa, Ryuma Niiyama, Yasuo Kuniyoshi, Physical Reservoir Computing in Tensegrity with Structural Softness and Ground Collision Dynamics, Journal of the Institute of Industrial Applications Engineers, 10.12792/jiiae.6.92, 6, 2, 92-99, 2018.04. |
| 18. |
Xi Chen, Satoshi Nishikawa, Kazutoshi Tanaka, Ryuma Niiyama, Yasuo Kuniyoshi, Bilateral teleoperation system for a musculoskeletal robot arm using a musculoskeletal exoskeleton, 2017 IEEE International Conference on Robotics and Biomimetics, ROBIO 2017, 10.1109/ROBIO.2017.8324833, 2018-January, 2734-2739, 2018.03, Musculoskeletal robots have several advantages in physical interactions. However, a method of teaching motion with physical interaction to a robot without the robot's model remains unavailable. Thus, we propose a bilateral teleoperation system for control of a musculoskeletal robot in this paper. This system enables an operator to operate the robot without the robot's model. The system includes a pneumatic musculoskeletal robot and pneumatic musculoskeletal exoskeleton with same joint and muscle composition. The operator wears the exoskeleton, feels the force that is exerted on the robot via the exoskeleton, and controls the robot by giving force to the exoskeleton. In the experiments, we found that the delay of this system is approximately 200 ms. Our system was able to give feedback force to the operator and change the magnitude of this force according to that of the external force. We showed that the operator can make the musculoskeletal robot perform a task with physical interaction with an environment using our systems. Thus, our system allows the operator to teach motion to a musculoskeletal robot with this interaction.. |
| 19. |
Taigo Yukisawa, Yasuaki Ishii, Satoshi Nishikawa, Ryuma Niiyama, Yasuo Kuniyoshi, Modeling of extensible pneumatic actuator with bellows (EPAB) for continuum arm, 2017 IEEE International Conference on Robotics and Biomimetics, ROBIO 2017, 10.1109/ROBIO.2017.8324762, 2018-January, 2303-2308, 2018.03, The ability of a continuum arm is influenced by the performance of an actuator. Although several extensible pneumatic actuators have been proposed in previous research, balancing strength with large strain is still a challenge. We propose an extensible pneumatic actuator with bellows (EPAB) that consists of a rubber tube and a highly packed bellows sleeve. We propose a parametric model of the EPAB that can comprise various bellows and rubber tubes. We measured the basic properties of four actuators with different parameters to verify the proposed model. We conducted evaluation experiments under two conditions: constant length with variable pressure and constant pressure with variable length. The experimental results indicate that the proposed model can roughly predict the measured data. The proposed extensible actuator has an unloaded strain of up to 350% at a pressure of 0.6 MPa.. |
| 20. |
Kazutoshi Tanaka, Satoshi Nishikawa, Ryuma Niiyama, Yasuo Kuniyoshi, Humanoid robot performing jump-And-hit motions using structure-integrated pneumatic cable cylinders, IEEE-RAS International Conference on Humanoid Robots, 10.1109/HUMANOIDS.2017.8246948, 696-702, 2017.12, In this study, a structure-integrated pneumatic cable cylinder has been developed to serve as an actuator for a humanoid robot. The performance of a robot in jumping and hitting a flying object (jump-And-hit motions) has been tested in order to predict its performance during immediate and dynamic whole-body motions. The authors tested the movement of the robofs arms using a cylinder, and jumping motions were simulated to determine the design parameters for the robot performing jump-And-hit operations. Test results for the robofs arms demonstrated that a two-kilogram arm, constructed using a C3, linder with a piston, 32 mm in diameter, moves 75 degrees in 0.44 s. Simulation results for a bipedal robot's forward jumping motion demonstrated that the top of its trunk, with a 50 mm joint force-torque ratio, moves forward by 3.0 m. Using the cylinder for the robofs arms and a joint with the above force-torque ratio in its legs, a prototype of a humanoid robot has been developed that performs a variety of jump-And-hit motions with a ball flying at it from different directions. Thus, the proposed design allows robots to conveniently perform immediate and dynamic whole-body motions.. |
| 21. |
Kenichi Fujita, Syogo Yonekura, Satoshi Nishikawa, Ryuma Niiyama, Yasuo Kuniyoshi, Environmental and Structural Effects on Physical Reservoir Computing with Tensegrity, 5th IIAE International Conference on Intelligent Systems and Image Processing (ICISIP), 2017.09. |
| 22. |
Satoshi Nishikawa, Kazuya Shida, Yasuo Kuniyoshi, Musculoskeletal quadruped robot with Torque-Angle Relationship Control System, Proceedings - IEEE International Conference on Robotics and Automation, 10.1109/ICRA.2016.7487595, 2016-June, 4044-4050, 2016.06, Systems with changeable mechanical properties show promise for expanding the applications of dynamic robots. We proposed the Torque-Angle Relationship Control System (TARCS) for musculoskeletal robots with changeable output properties. First, we formulated TARCS and examined its static properties. Next, we used TARCS to change the properties and investigated the effect of the same on the jumping ability through simulations. We found that TARCS in a biarticular muscle determined the general shape of the jumpable range. Furthermore, TARCS in a monoarticular muscle could change the amplitude of the jumpable range. Both TARCS also changed the directional property of the reaction to the disturbance. Finally, we developed a musculoskeletal quadruped robot in which TARCS was implemented. This robot could change its jumping direction using TARCS, and it jumped to a height of 0.254 m at the lowest point of its body.. |
| 23. |
Satoshi Nishikawa, Tomohiro Kobayashi, Toshihiko Fukushima, Yasuo Kuniyoshi, Pole vaulting robot with dual articulated arms that can change reaching position using active bending motion, IEEE-RAS International Conference on Humanoid Robots, 10.1109/HUMANOIDS.2015.7363564, 2015-December, 395-400, 2015.12, Elasticity is an important factor in enhancing the physical capabilities of robots. Pole vaulting is an interesting task because a large elastic pole changes the trajectory of the robot drastically. Moreover, the robot can change its behavior by manipulating the flexible pole during a long pole-support phase. In this study, we investigated how the reaching point of pole vaulting was changed by an active bending motion because it is important for robots to move to the desired place. To examine the effect of motion, we used a multiple pendulum model and a robot having dual articulated arms with grippers. Simulation results showed that reaching positions were changed by the switching time of the active bending motion. A relatively late switching time allowed robots to vault to a farther position. However, a very late switching time had the opposite effect. Then, we developed a pole vaulting robot having dual articulated arms with grippers for the application of humanoid robots. Pole vaulting experiments using this robot showed the same tendency in the simulation. These results indicated that the reaching position of pole vaulting could be controlled by the switching time of active bending. Further, the robot reached a height of 1.67 m by releasing the pole.. |
| 24. |
Shih Yin Chang, Kenta Takashima, Satoshi Nishikawa, Ryuma Niiyama, Takao Someya, Hiroshi Onodera, Yasuo Kuniyoshi, Design of small-size pouch motors for rat gait rehabilitation device, Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 10.1109/EMBC.2015.7319413, 2015-November, 4578-4581, 2015.11, Recent studies have demonstrated that active gait training can recover voluntary locomotive ability of paralyzed rats. Rehabilitation devices used for studying spinal cord injury to date are usually fixed on a treadmill, but they have been used only slightly for active training. To process active rehabilitation, a wearable, lightweight device with adequate output is needed. Pouch motors, soft pneumatic actuators, are extremely light and have other benefits such as low cost, easy fabrication, and highly customizable design. They can be used to develop active gait rehabilitation devices. However, performance details of different motor designs have not been examined. As described herein, to build a wearable gait assistive device for rat study, we specifically examine how to design small pouch motors with a good contraction ratio and force output. Results show that pouch performance decreases dramatically with size, but better output is obtainable by separation into small 0.8 length-to-width ratio rooms. We used this knowledge to produce an assistive robot suit for gait rehabilitation and to test it with paralyzed rats. Results show that these small pouches can produce sufficient power to control hip joint movements during gait training. They can reveal the potential for new pouch motor applications for spinal cord injury studies.. |
| 25. |
Toshihiko Fukushima, Satoshi Nishikawa, Yasuo Kuniyoshi, Active bending motion of pole vault robot to improve reachable height, Proceedings - IEEE International Conference on Robotics and Automation, 10.1109/ICRA.2014.6907471, 4208-4214, 2014.09, For robots using elastic devices, pole vault is a particularly interesting task because poles have large differences from previously studied elastic elements in terms of their elastic capacity. The active actuation of the agent in 'pole support phase' plays important roles in improving vaulting performance. Investigating this actuation can contribute to the design of novel control strategies during the time when the agent contacts with environment through the elastic device. In this study, we specifically examined an active bending effect performed in the 'pole support phase.' We analyzed the active bending effect on reachable height (vaulting height) using the 'Transitional Buckling Model.' We applied this active bending theory to a robot and verified the active bending effect to improve vaulting height. Results show that active bending motion in the 'pole support phase' improves the pole vault performance and that the timing of the bending direction change is an important factor for defining the vaulting performance. These results will facilitate the application of robots using large elasticity.. |
| 26. |
Kazutoshi Tanaka, Satoshi Nishikawa, Yasuo Kuniyoshi, Adjustment of pressure in antagonistic joints with pneumatic artificial muscles for rapid reacting motions, Mobile Service Robotics: Proceedings of the 17th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, 10.1142/9789814623353_0022, 183-190, 2014.07, Rapid reacting motions are important for robots to adjust to changes in the real world, which is constantly changing drastically. Pneumatic artificial muscles (PAMs) have been used as actuators of fast-moving robots. Robots equipped with PAMs can move adaptively and dynamically using passive properties of PAMs. In this study, we considered preparation for fast reacting motions by robots equipped with joints driven by competing PAMs (antagonistic PAMdriven joints) as using active properties of PAMs. Specifically, we investigated a method of adjusting initial pressures in PAM-driven joints increasing the maximum joint velocity generated in a short time. We found the optimal initial pressure in PAM-driven joints considering a mechanical delay of PAMs in simulations. Additionally, we verified the validity of results in the simulations using an actual robotic arm.. |
| 27. |
Satoshi Nishikawa, Kazutoshi Tanaka, Kazuya Shida, Toshihiko Fukushima, Ryuma Niiyama, Yasuo Kuniyoshi, A musculoskeletal bipedal robot designed with angle-dependent moment arm for dynamic motion from multiple states, Advanced Robotics, 10.1080/01691864.2013.876936, 28, 7, 487-496, 2014.04, When robots make smooth transitions in dynamic motions, they must exert large force over widely various postures. To expand the range of postures that robots can take during dynamic motions, we propose that robots be designed with an Angle-Dependent Moment Arm (ADMA) with biased pivot, for which torque characteristics of actuators attached to joints are adjustable. From jumping simulations of robotic legs designed with ADMA, we demonstrate that ADMA improves robustness to postural and motion timing changes by shifts of the optimal posture, which are also observed in jumping experiments using a full-sized, bipedal robot. © 2014 Taylor & Francis and The Robotics Society of Japan.. |
| 28. |
Kazutoshi Tanaka, Satoshi Nishikawa, Yasuo Kuniyoshi, Effect of preliminary motions on agile motions, 2013 16th International Conference on Advanced Robotics, ICAR 2013, 10.1109/ICAR.2013.6766534, 1-6, 2013.11, Robots must complete motions in a short time in uncertain and variable real world environments. However, uncertainty in the real world has only rarely been considered in studies of agile motions by robots. Consequently, methods for agile motions incorporating uncertainty must be proposed. Preceding agile motions, human preparatory motions (preliminary motions) are often observed. For insight, we specifically addressed human preliminary motions as preparation for agile motion. The effect of preliminary motions on human agile motions has been studied in sports biomechanics. However, no general model of preliminary motion has been proposed. Consequently, findings related to human preliminary motions are difficult to apply to robots. Therefore, we proposed a numerical model of preliminary motions to verify the effect of preliminary motions on robots' agile motions in numerical simulations. Using simulations, we investigated the completion time for reaching motions by simple robot arms. Results showed that robots can prepare and move quickly to an uncertain target using our proposed method of preliminary motions. © 2013 IEEE.. |
| 29. |
Satoshi Nishikawa, Toshihiko Fukushima, Yasuo Kuniyoshi, Effective timing of swing-up motion by a pole-vaulting robot, 2013 16th International Conference on Advanced Robotics, ICAR 2013, 10.1109/ICAR.2013.6766528, 1-6, 2013.11, Elasticity has been used in many dynamic robots because it can regenerate energy or absorb collision shock. However, the role of elasticity has remained only supplementary. Its potential usefulness in dynamic motion is largely unquantified. Therefore, we specifically examine a task with an extremely large elastic element: pole vaulting. In pole-vaulting research, active operations by an agent are known to improve vaulting performance. Previously, we investigated an active bending effect while hanging from a pole in a simulation. These active operations are generated from the body motion. In this study, we specifically examine the effect of inertial force resulting from motion of the body. We hypothesize that swing-up motion performed closer to the pole planting point (i.e. later in timing) improves vaulting performance. We developed a robot that can exert a large inertial force, and conducted pole-vaulting experiments to verify the hypothesis. Results showed that energy loss is less when swing-up motion occurs later. Our results support the hypothesis and indicate that the timing of swing-up motion is an important factor contributing to vaulting performance. © 2013 IEEE.. |
| 30. |
Satoshi Nishikawa, Kazutoshi Tanaka, Kazuya Shida, Ryuma Niiyama, Yasuo Kuniyoshi, Angle-Dependent Moment Arm with Biased Pivot for Jumping from Various Squatting Positions, 6th International Symposium on Adaptive Motion of Animals and Machines (AMAM), 2013.03. |
| 31. |
Kazuya Shida, Satoshi Nishikawa, Yasuo Kuniyoshi, Design and Test of Torque-Angle Relationship Control System, 6th International Symposium on Adaptive Motion of Animals and Machines (AMAM), 2013.03. |
| 32. |
Toshihiko Fukushima, Satoshi Nishikawa, Kazutoshi Tanaka, Yasuo Kuniyoshi, Transitional Buckling Model for Active Bending Effect in Pole Vault, 6th International Symposium on Adaptive Motion of Animals and Machines (AMAM), 2013.03. |
| 33. |
Kazutoshi Tanaka, Satoshi Nishikawa, Yasuo Kuniyoshi, Improvement of energy consumption by movement of center of rotation of joint, Nature-Inspired Mobile Robotics, 10.1142/9789814525534_0036, 273-280, 2013.01, Robots mimicking the structure of the musculoskeletal systems have been de- veloped in order to realize high physical performance or to reveal the con- tribution of the musculoskeletal systems to body movements. The movement of center of rotation (CoR) of biological joints have been focused on in var- ious research fields. However, to date, the isolated contribution of the joint displaceable center of rotation (JDCR) on physical performance has not yet been analyzed. Revealing this contribution is expected to provide guidelines for the design methodology of robots. In this paper, we compared two mod- els in order to investigate the effect of JDCR on physical performance. The first model has two virtual links to represent the joint including the JDCR (JDCR model). The second model represents the joint with fixed CoR (JFCR model). We evaluated the two models by analyzing energy consumption during reaching motions. In addition, we examined energy consumption while the end effector traced a circular trajectory using extended models (eJDCR model and eJFCR model). The results showed that the energy consumption of models which include JDCR lower than models which does not under all tested con- ditions. This study suggested that a joint including JDCR can improve energy consumption.. |
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Ryuma Niiyama, Satoshi Nishikawa, Yasuo Kuniyoshi, Biomechanical approach to open-loop bipedal running with a musculoskeletal athlete robot, Advanced Robotics, 10.1163/156855311X614635, 26, 3-4, 383-398, 2012.04, In this study, a musculoskeletal robot is used as a tool to investigate how animals control their complex body. Sprinting is a challenging task that requires maximizing the potential resources of a musculoskeletal structure. Our approach to robotic sprinting is the Athlete Robot - a musculoskeletal robot with elastic blade feet controlled by feedforward motor command. We use a catapult launcher to provide a stable start to a sprint, and then examine the relation between the initial velocity imparted by the launcher and the change in orientation of the robot. We also investigate the influence of the change in elasticity of the blade foot. The results show that acceleration causes anterior inclination after the first step. The elasticity of the foot dominates the duration of the support phase. The musculoskeletal system of the Athlete Robot is modified to suit catapulted running. Based on the results from real robot experiments, we can provide a consistent propelling force using the catapult launcher. We demonstrate the Athlete Robot running for five steps after a catapult launch, using only feedforward command. © 2012 Koninklijke Brill NV, Leiden and The Robotics Society of Japan.. |
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Satoshi Nishikawa, Ryuma Niiyama, Yasuo Kuniyoshi, Running Motion in a Musculoskeletal Bipedal Robot using Muscle Activation Pattern Control Based on a Human Electromyogram, 5th International Symposium on Adaptive Motion of Animals and Machines (AMAM), 2011.10. |
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Yasunori Yamada, Satoshi Nishikawa, Kazuya Shida, Ryuma Niiyama, Yasuo Kuniyoshi, Neural-body coupling for emergent locomotion: A musculoskeletal quadruped robot with spinobulbar model, IEEE International Conference on Intelligent Robots and Systems, 10.1109/IROS.2011.6048360, 1499-1506, 2011.09, To gain a synthetic understanding of how the body and nervous system co-create animal locomotion, we propose an investigation into a quadruped musculoskeletal robot with biologically realistic morphology and a nervous system. The muscle configuration and sensory feedback of our robot are compatible with the mono- and bi-articular muscles of a quadruped animal and with its muscle spindles and Golgi tendon organs. The nervous system is designed with a biologically plausible model of the spinobulbar system with no pre-defined gait patterns such that mutual entrainment is dynamically created by exploiting the physics of the body. In computer simulations, we found that designing the body and the nervous system of the robot with the characteristics of biological systems increases information regularities in sensorimotor flows by generating complex and coordinated motor patterns. Furthermore, we found similar results in robot experiments with the generation of various coordinated locomotion patterns created in a self-organized manner. Our results demonstrate that the dynamical interaction between the physics of the body with the neural dynamics can shape behavioral patterns for adaptive locomotion in an autonomous fashion. © 2011 IEEE.. |
| 37. |
Ryuma Niiyama, Satoshi Nishikawa, Yasuo Kuniyoshi, Athlete robot with applied human muscle activation patterns for bipedal running, 2010 10th IEEE-RAS International Conference on Humanoid Robots, Humanoids 2010, 10.1109/ICHR.2010.5686316, 498-503, 2010.12, The essential component of legged locomotion is control of the ground reaction force. To understand the role of the musculoskeletal body in dynamic locomotion, we investigate bipedal running using a musculoskeletal "Athlete Robot". The configuration of the muscles in the robot is compatible with the human. The spring-like property of the human lower leg during running is modeled as an elastic blade foot based on findings from biomechanics. The motor command of the robot is represented by time series data of muscle activation. The muscle activation patterns are determined from numerical calculation using a model of the musculoskeletal leg based on the measurement of muscle activity and kinetic data of the human movements. In the simulation results, the robot runs 8 steps with a speed of 3 m/s. We also demonstrate that the real bipedal robot is able to run for several steps. ©2010 IEEE.. |
