Adaptive neural fault-tolerant prescribed performance control of a rehabilitation exoskeleton for lower limb passive training.

Journal: ISA transactions
PMID: 38853110

Abstract

This article studies the passive tracking problem of a wearable exoskeleton for lower limb rehabilitation therapy in the face of unmodeled dynamics, interactive friction, disturbance, prescribed performance constraints, and actuator faults. Adaptive neural networks and a smooth performance function are incorporated to establish a novel fault-tolerant tracking scheme, which can not only compensate for the nonlinear uncertainties and disturbance, but also handle the actuator fault with guaranteed tracking performance. A state feedback controller is presented by using the full state information and an output feedback controller is developed when the angular velocity is unavailable. The differential explosion issue of the backstepping technique is resolved by constructing a first-order filter and the unmeasurable velocity is estimated by a nonlinear observer. Semiglobal uniform boundedness stabilities of the exoskeleton system are proved via the Lyapunov direct method. The tracking performances of the designed control approaches are tested by comparative simulations.

Authors

  • Yong Yang
    Department of Radiation Oncology, Stanford University, CA, USA.
  • Deqing Huang
    Institute of Systems Science and Technology, School of Electrical Engineering, Southwest Jiaotong University, Chengdu, 611756, China.
  • Lei Ma
    School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, Sichuan, China. Electronic address: leima@wit.edu.cn.
  • Xia Liu
    Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Science, Haikou 571010, People's Republic of China; Key Laboratory of Monitoring and Control of Tropical Agricultural and Forest Invasive Alien Pests, Ministry of Agriculture, Haikou 571010, People's Republic of China.
  • Yanan Li
    Beijing Key Laboratory of Flavor Chemistry, Beijing Technology and Business University Beijing 100048 China chenht@th.btbu.edu.cn yangshaoxiang@th.btbu.edu.cn.

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