Repetitive Control of Robotic Joint With Variable Impedance Utilizing Agonist-Antagonist Muscle Pair Structure Based on Virtual Trajectories
Realizing accurate trajectory-tracking control for flexible robotic joints using a model-free approach is challenging. In this study, the repetitive control based on virtual trajectory, which is a model-free control method proposed for flexible human multi-joints, is extended and applied to a real r...
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IEEE
2025-01-01
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| Series: | IEEE Access |
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| Online Access: | https://ieeexplore.ieee.org/document/10849553/ |
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| author | Kaho Umeda Yinlai Jiang Hiroshi Yokoi Shunta Togo |
| author_facet | Kaho Umeda Yinlai Jiang Hiroshi Yokoi Shunta Togo |
| author_sort | Kaho Umeda |
| collection | DOAJ |
| description | Realizing accurate trajectory-tracking control for flexible robotic joints using a model-free approach is challenging. In this study, the repetitive control based on virtual trajectory, which is a model-free control method proposed for flexible human multi-joints, is extended and applied to a real robotic joint with a variable mechanical impedance mechanism. The virtual trajectory is modeled by a time series of the equilibrium position of the spring. In conventional methods, the virtual trajectory is corrected according to the trajectory error resulting from repetitive control. To achieve trajectory tracking even with a soft joint, this study proposes a strategy for starting repetitive control with a high joint impedance and switching to a lower joint impedance after convergence to the target trajectory, thereby successively correcting the estimated impedance change ratio by repetitive control. We developed a robotic joint with an agonist-antagonist muscle pair structure that can easily change its mechanical impedance using a position-controlled motor combined with a grommet, which changes its stiffness nonlinearly with respect to elongation, in addition to a wire traction mechanism as the control target. The results of simulations and real robot experiments demonstrated that the proposed method can achieve trajectory-tracking control even when the joint impedance is so low that the trajectory diverges from that of the conventional method. These results show that the proposed method is capable of trajectory tracking control while maintaining joint softness even when the dynamics of the control target and the impedance values before and after the change are unknown, that is, model-free. |
| format | Article |
| id | doaj-art-4625449785ab4a9da419a483e730f51b |
| institution | Kabale University |
| issn | 2169-3536 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Access |
| spelling | doaj-art-4625449785ab4a9da419a483e730f51b2025-01-31T00:01:50ZengIEEEIEEE Access2169-35362025-01-0113168661687810.1109/ACCESS.2025.353263310849553Repetitive Control of Robotic Joint With Variable Impedance Utilizing Agonist-Antagonist Muscle Pair Structure Based on Virtual TrajectoriesKaho Umeda0Yinlai Jiang1https://orcid.org/0000-0002-0825-6444Hiroshi Yokoi2https://orcid.org/0000-0001-8571-1175Shunta Togo3https://orcid.org/0000-0002-3464-0765Department of Mechanical and Intelligent Systems Engineering, The University of Electro-Communications, Tokyo, JapanCenter for Neuroscience and Biomedical Engineering, The University of Electro-Communications, Tokyo, JapanDepartment of Mechanical and Intelligent Systems Engineering, The University of Electro-Communications, Tokyo, JapanDepartment of Mechanical and Intelligent Systems Engineering, The University of Electro-Communications, Tokyo, JapanRealizing accurate trajectory-tracking control for flexible robotic joints using a model-free approach is challenging. In this study, the repetitive control based on virtual trajectory, which is a model-free control method proposed for flexible human multi-joints, is extended and applied to a real robotic joint with a variable mechanical impedance mechanism. The virtual trajectory is modeled by a time series of the equilibrium position of the spring. In conventional methods, the virtual trajectory is corrected according to the trajectory error resulting from repetitive control. To achieve trajectory tracking even with a soft joint, this study proposes a strategy for starting repetitive control with a high joint impedance and switching to a lower joint impedance after convergence to the target trajectory, thereby successively correcting the estimated impedance change ratio by repetitive control. We developed a robotic joint with an agonist-antagonist muscle pair structure that can easily change its mechanical impedance using a position-controlled motor combined with a grommet, which changes its stiffness nonlinearly with respect to elongation, in addition to a wire traction mechanism as the control target. The results of simulations and real robot experiments demonstrated that the proposed method can achieve trajectory-tracking control even when the joint impedance is so low that the trajectory diverges from that of the conventional method. These results show that the proposed method is capable of trajectory tracking control while maintaining joint softness even when the dynamics of the control target and the impedance values before and after the change are unknown, that is, model-free.https://ieeexplore.ieee.org/document/10849553/Agonist-antagonist muscle pairflexible jointrepetitive controlvariable impedancevirtual trajectory |
| spellingShingle | Kaho Umeda Yinlai Jiang Hiroshi Yokoi Shunta Togo Repetitive Control of Robotic Joint With Variable Impedance Utilizing Agonist-Antagonist Muscle Pair Structure Based on Virtual Trajectories IEEE Access Agonist-antagonist muscle pair flexible joint repetitive control variable impedance virtual trajectory |
| title | Repetitive Control of Robotic Joint With Variable Impedance Utilizing Agonist-Antagonist Muscle Pair Structure Based on Virtual Trajectories |
| title_full | Repetitive Control of Robotic Joint With Variable Impedance Utilizing Agonist-Antagonist Muscle Pair Structure Based on Virtual Trajectories |
| title_fullStr | Repetitive Control of Robotic Joint With Variable Impedance Utilizing Agonist-Antagonist Muscle Pair Structure Based on Virtual Trajectories |
| title_full_unstemmed | Repetitive Control of Robotic Joint With Variable Impedance Utilizing Agonist-Antagonist Muscle Pair Structure Based on Virtual Trajectories |
| title_short | Repetitive Control of Robotic Joint With Variable Impedance Utilizing Agonist-Antagonist Muscle Pair Structure Based on Virtual Trajectories |
| title_sort | repetitive control of robotic joint with variable impedance utilizing agonist antagonist muscle pair structure based on virtual trajectories |
| topic | Agonist-antagonist muscle pair flexible joint repetitive control variable impedance virtual trajectory |
| url | https://ieeexplore.ieee.org/document/10849553/ |
| work_keys_str_mv | AT kahoumeda repetitivecontrolofroboticjointwithvariableimpedanceutilizingagonistantagonistmusclepairstructurebasedonvirtualtrajectories AT yinlaijiang repetitivecontrolofroboticjointwithvariableimpedanceutilizingagonistantagonistmusclepairstructurebasedonvirtualtrajectories AT hiroshiyokoi repetitivecontrolofroboticjointwithvariableimpedanceutilizingagonistantagonistmusclepairstructurebasedonvirtualtrajectories AT shuntatogo repetitivecontrolofroboticjointwithvariableimpedanceutilizingagonistantagonistmusclepairstructurebasedonvirtualtrajectories |