Development of Optimal Fuzzy-PID Controller for an Assistant Human Knee Exoskeleton System

In this paper, an optimal fuzzy-PID controller is proposed for a knee exoskeleton model for patients with knee problems caused by strokes, post-polio, osteoarthritis, etc. For this purpose, a fuzzy control logic based proportional integral derivative (Fuzzy-PID) controller is considered. The fuzzy con-troller in the proposed control structure is used to adjust the PID controller parameters for the knee exoskeleton model. The error between the targeted angle and actual angle of knee exoskeleton system and the change of this error are taken as the input variables of the fuzzy controller. The output variables are chosen as the parameters of PID controller. The membership functions of the fuzzy controller are optimized with a well-known optimization algorithm called class topper optimization. The performance of the proposed controller is examined under different scenarios and plotted on a graph.