An adaptive seamless assist-as-needed control scheme for lower extremity rehabilitation robots

Autor: Xiaodong Zhang, Hanzhe Li, Gui Yin, Runlin Dong, Huosheng Hu
Rok vydání: 2020
Předmět:
Zdroj: Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering. 235:723-734
ISSN: 2041-3041
0959-6518
DOI: 10.1177/0959651820970720
Popis: Most control methods deployed in lower extremity rehabilitation robots cannot automatically adjust to different gait cycle stages and different rehabilitation training modes for different impairment subjects. This article presents a continuous seamless assist-as-needed control method based on sliding mode adaptive control. A forgetting factor is introduced, and a small trajectory deviation from reference normal gait trajectory is used to learn the rehabilitation level of a human subject in real time. The assistance torque needed to complete the reference normal gait trajectory is learned through radial basis function neural networks, so that the rehabilitation robot can adaptively provide the assistance torque according to subject’s needs. The performance and efficiency of this adaptive seamless assist-as-needed control scheme are tested and validated by 12 volunteers on a rehabilitation robot prototype. The results show that the proposed control scheme could adaptively reduce the robotic assistance according to subject’s rehabilitation level, and the robotic assistance torque depends on the forgetting factor and the active participation level of subjects.
Databáze: OpenAIRE