Terminal Synergetic Control Based Cheetah Optimizer for Knee-Exoskeleton Systems

Abstract

The knee-exoskeleton is mechanical devices which are designed to help people rehabilitate impaired limb mobility and replace the use of physiotherapists. The scope of this study is rehabilitation assistance for the lower limb (i.e. knee of the leg). Due to the high level of complexity and nonlinearity, various control algorithms have been developed to the knee-exoskeleton system to handle these challenges. This study presents a tracking control design of the angular position for the lower limb exoskeleton knee system based on a terminal synergetic control (TSC) strategy. In addition, the cheetah optimizer (CO) algorithm is introduced and embedded in the design to adjust the design parameters of the controller for further optimization of its performance based on the root mean of square errors (RMSE). The superiority of the proposed control method is shown in comparison to the conventional synergetic control (SC) method via computer simulations using MATLAB. The simulations results show that the TSC can improve the response of the system. The numerical value reveals that the RMSE is reduced by 14.9%. In addition, the simulation results validate the efficacy of the proposed approach in the presence of external disturbances where the RMSE is reduced by 39.1%.