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Integrated Observer-based Fixed-time Control with Backstepping Method for Exoskeleton Robot

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Abstract

To achieve the fast convergence and tracking precision of a robotic upper-limb exoskeleton, this paper proposes an observer-based integrated fixed-time control scheme with a backstepping method. Firstly, a typical 5 DoF (degrees of freedom) dynamics is constructed by Lagrange equations and processed for control purposes. Secondly, second-order sliding mode controllers (SOSMC) are developed and novel sliding mode surfaces are introduced to ensure the fixed-time convergence of the human-robot system. Both the reaching time and settling time are proved to be bounded with certain values independent of initial system conditions. For the purpose of rejecting the matched and unmatched disturbances, nonlinear fixed-time observers are employed to estimate the exact value of disturbances and compensate the controllers online. Ultimately, the synthesis of controllers and disturbance observers is adopted to achieve the excellent tracking performance and simulations are given to verify the effectiveness of the proposed control strategy.

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Acknowledgements

This work was supported by National Natural Science Foundation of China (Nos. 61703134, 61703135, 61773151, 61503118 and 61871173), Natural Science Foundation of Hebei Province (Nos. F2015202150, F2016202327 and F2018202279), Natural Science Foundation of Tianjin (No. 17JCQNJC04400), the Foundation of Hebei Educational Committee (Nos. QN2015068 and ZD2016071), the Colleges and Universities in Hebei Province Science and Technology Research Youth Fund (No. ZC2016020) and the Graduate Innovation Funding Project of Hebei Province (No. CXZZBS2017038).

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Authors and Affiliations

  1. School of Artificial Intelligence, Hebei University of Technology, Tianjin, 300130, China

    Gao-Wei Zhang, Peng Yang, Jie Wang, Jian-Jun Sun & Yan Zhang

  2. Enginnering Research Center of Intelligent Rehabilitation and Detection Technology, Ministry of Education, Tianjin, 300130, China

    Gao-Wei Zhang, Peng Yang, Jie Wang, Jian-Jun Sun & Yan Zhang

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  1. Gao-Wei Zhang
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  2. Peng Yang
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  3. Jie Wang
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Correspondence to Jie Wang.

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Recommended by Associate Editor Xian-Dong Ma

Gao-Wei Zhang received the B. Sc. degree in automation from Hebei University of Technology, China in 2014. Currently, he is a Ph. D. degree candidate in control theory and control engineering in Hebei University of Technology, China.

His research interests include nonlinear control theory, sliding mode control and wearable exoskeleton.

Peng Yang recieved the M. Sc. degree in automation from Harbin Institute of Technology, China in 1988, and recieved the Ph. D. degree in electrical engineering from Hebei University of Technology, China in 2001. Since 1982, he has been in Hebei University of Technology where his present position is professor. From January to May in 2005, he has been in University of Munich as a visiting scholar. He has published more than 100 journal and conference papers. His awards and honors include the Natural Science Award of Hebei Province, Science and Technology Progress Award of Hebei Province, Natural Science Award of Chongqing.

His research interests include complex system modeling and control, robot control and prosthetics.

Jie Wang received the M. Sc. degree in basic mathematics from Northeastern University, China in 2010, and the Ph. D. degree in control science and engineering from Tianjin University, China in 2014. Since 2014, she has been in Hebei University of Technology where her present position is associate professor. She has published about 20 papers and one of them is high cited paper in ESI.

Her research interests include nonlinear control theory, sliding mode control and observation with applications to hypersonic vehicle, quadrotor aircraft and wearable exoskeleton.

Jian-Jun Sun received the B.Sc. degree in measurement and control technology and instruments from Taiyuan University of Technology, China in 2016. He is currently a Ph. D. degree candidate in control theory and control engineering in Hebei University of Technology, China.

His research interests include nonlinear control theory and sliding mode control.

Yan Zhang received the M. Sc. degree in automation from Hebei University of Technology, China in 1999, and the Ph. D. degree in control theory and control engineering from Nankai University, China in 2004. She has been Hebei University of Technology since 1999 where her present position is professor. She has hosted and participated in several National Natural Science Foundations of China and the Natural Science Foundations of Hebei Province projects, China.

Her research interests include nonlinear system control, intelligent algorithm and prosthetics.

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Zhang, GW., Yang, P., Wang, J. et al. Integrated Observer-based Fixed-time Control with Backstepping Method for Exoskeleton Robot. Int. J. Autom. Comput. 17, 71–82 (2020). https://doi.org/10.1007/s11633-019-1201-z

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