Human-centred adaptive control of lower limb rehabilitation robot based on human–robot interaction dynamic model

Abstract

A rehabilitation robot can effectively alleviate the shortcomings and deficiencies of traditional treatments. The early stages of rehabilitation training use passive control based on a predefined trajectory. The goal of passive control is to control the motion of the robot, rather than the real motion of the human. However, the human and robot are connected by bands; thus, errors exist between them, and these errors affect the outcome of the rehabilitation training. This study proposes human-centred adaptive control of a lower limb rehabilitation robot based on a dynamic model of human–robot interactions. An equivalent spring model in three-dimensional space is proposed for expressing the interaction torque between the human and robot, reflecting the torque exerted by the robot on the human. A dynamic model for the human–robot system is established based on the human–robot interaction model. To overcome the uncertainty regarding the parameters of the human limbs and robots and that of the stiffness coefficient in the interaction force model, an adaptive controller is designed, and the stability of the system is analysed. The simulation results indicate the effectiveness of the controller.