Lower limb exoskeleton parasitic force modeling and minimizing with an adaptive trajectory controller

Libo Zhou; Weihai Chen; Shaoping Bai; Jianhua Wang; Zheng Zhao; Xiaoming Zhao; Xinyi Yu

doi:10.1016/j.mechmachtheory.2022.104731

Lower limb exoskeleton parasitic force modeling and minimizing with an adaptive trajectory controller

Libo Zhou, Weihai Chen^*, Shaoping Bai, Jianhua Wang, Zheng Zhao, Xiaoming Zhao, Xinyi Yu

^*Corresponding author for this work

Research output: Contribution to journal › Journal article › Research › peer-review

9 Citations (Scopus)

Abstract

Parasitic force caused by joint misalignment is a common and challenging problem in the design and control of lower limb exoskeletons due to the complex human joint morphology. The force will generate high tangential force on the skin, which leads pain or at least discomfort for the wearer. This paper presents a model of the parasitic force in a lower limb exoskeleton, aiming to minimize this force with an adaptive trajectory controller (ATC). The controller uses parasitic force in the shank between the human and the exoskeleton as the control signal, and adjusts joint trajectories to minimize the parasitic force. In this paper, a lower limb exoskeleton with two-degrees of freedom (DOFs) in the knee joint is presented. Parasitic force relates to the joint misalignment is modeled and analyzed, upon which a trajectory controller is developed. Both simulations and experimental results are included, which showed that the proposed method was capable of effectively reducing the parasitic force in motion assistance.

Original language	English
Article number	104731
Journal	Mechanism and Machine Theory
Volume	170
ISSN	0094-114X
DOIs	https://doi.org/10.1016/j.mechmachtheory.2022.104731
Publication status	Published - Apr 2022

Bibliographical note

Funding Information:
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Jianhua Wang reports was provided by National Natural Science Foundation of China.

Funding Information:
The authors would like to thank Yinping Zhang, Yang Li, Lei Zhang, Xin Chang, Pinghua Ai and Zhaochen Li for their help during the fabrication and experiments of the BLLE-3. This work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant No. 61773042 , 51975029 and 51975002 , in part by the Key Research and Development Program of Zhejiang Province under Project 2021C03050, in part by the Scientific Research Project of Agriculture and Social Development of Hangzhou under Grant 2020ZDSJ0881, in part by Zhejiang Provincial Natural Science Foundation of China under Grant No. LQ22F030021, and in part by the Macao Science and Technology Development Fund under Project 0022/2019/AKP .

Publisher Copyright:
© 2022

Keywords

Adaptive trajectory controller
Lowe limb exoskeleton
Parasitic force minimization
Parasitic force modeling

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title = "Lower limb exoskeleton parasitic force modeling and minimizing with an adaptive trajectory controller",

abstract = "Parasitic force caused by joint misalignment is a common and challenging problem in the design and control of lower limb exoskeletons due to the complex human joint morphology. The force will generate high tangential force on the skin, which leads pain or at least discomfort for the wearer. This paper presents a model of the parasitic force in a lower limb exoskeleton, aiming to minimize this force with an adaptive trajectory controller (ATC). The controller uses parasitic force in the shank between the human and the exoskeleton as the control signal, and adjusts joint trajectories to minimize the parasitic force. In this paper, a lower limb exoskeleton with two-degrees of freedom (DOFs) in the knee joint is presented. Parasitic force relates to the joint misalignment is modeled and analyzed, upon which a trajectory controller is developed. Both simulations and experimental results are included, which showed that the proposed method was capable of effectively reducing the parasitic force in motion assistance.",

keywords = "Adaptive trajectory controller, Lowe limb exoskeleton, Parasitic force minimization, Parasitic force modeling",

author = "Libo Zhou and Weihai Chen and Shaoping Bai and Jianhua Wang and Zheng Zhao and Xiaoming Zhao and Xinyi Yu",

note = "Funding Information: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Jianhua Wang reports was provided by National Natural Science Foundation of China. Funding Information: The authors would like to thank Yinping Zhang, Yang Li, Lei Zhang, Xin Chang, Pinghua Ai and Zhaochen Li for their help during the fabrication and experiments of the BLLE-3. This work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant No. 61773042 , 51975029 and 51975002 , in part by the Key Research and Development Program of Zhejiang Province under Project 2021C03050, in part by the Scientific Research Project of Agriculture and Social Development of Hangzhou under Grant 2020ZDSJ0881, in part by Zhejiang Provincial Natural Science Foundation of China under Grant No. LQ22F030021, and in part by the Macao Science and Technology Development Fund under Project 0022/2019/AKP . Publisher Copyright: {\textcopyright} 2022",

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AU - Chen, Weihai

AU - Bai, Shaoping

AU - Wang, Jianhua

AU - Zhao, Zheng

AU - Zhao, Xiaoming

AU - Yu, Xinyi

N1 - Funding Information: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Jianhua Wang reports was provided by National Natural Science Foundation of China. Funding Information: The authors would like to thank Yinping Zhang, Yang Li, Lei Zhang, Xin Chang, Pinghua Ai and Zhaochen Li for their help during the fabrication and experiments of the BLLE-3. This work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant No. 61773042 , 51975029 and 51975002 , in part by the Key Research and Development Program of Zhejiang Province under Project 2021C03050, in part by the Scientific Research Project of Agriculture and Social Development of Hangzhou under Grant 2020ZDSJ0881, in part by Zhejiang Provincial Natural Science Foundation of China under Grant No. LQ22F030021, and in part by the Macao Science and Technology Development Fund under Project 0022/2019/AKP . Publisher Copyright: © 2022

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N2 - Parasitic force caused by joint misalignment is a common and challenging problem in the design and control of lower limb exoskeletons due to the complex human joint morphology. The force will generate high tangential force on the skin, which leads pain or at least discomfort for the wearer. This paper presents a model of the parasitic force in a lower limb exoskeleton, aiming to minimize this force with an adaptive trajectory controller (ATC). The controller uses parasitic force in the shank between the human and the exoskeleton as the control signal, and adjusts joint trajectories to minimize the parasitic force. In this paper, a lower limb exoskeleton with two-degrees of freedom (DOFs) in the knee joint is presented. Parasitic force relates to the joint misalignment is modeled and analyzed, upon which a trajectory controller is developed. Both simulations and experimental results are included, which showed that the proposed method was capable of effectively reducing the parasitic force in motion assistance.

AB - Parasitic force caused by joint misalignment is a common and challenging problem in the design and control of lower limb exoskeletons due to the complex human joint morphology. The force will generate high tangential force on the skin, which leads pain or at least discomfort for the wearer. This paper presents a model of the parasitic force in a lower limb exoskeleton, aiming to minimize this force with an adaptive trajectory controller (ATC). The controller uses parasitic force in the shank between the human and the exoskeleton as the control signal, and adjusts joint trajectories to minimize the parasitic force. In this paper, a lower limb exoskeleton with two-degrees of freedom (DOFs) in the knee joint is presented. Parasitic force relates to the joint misalignment is modeled and analyzed, upon which a trajectory controller is developed. Both simulations and experimental results are included, which showed that the proposed method was capable of effectively reducing the parasitic force in motion assistance.

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SN - 0094-114X

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JO - Mechanism and Machine Theory

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ER -

Lower limb exoskeleton parasitic force modeling and minimizing with an adaptive trajectory controller

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