Development and Optimization of PID Control for FES Knee Exercise in Hemiplegic Rehabilitation

Functional electrical stimulation have been used in hemiplegic rehabilitation by contracting muscles of paralyzed limb in performing limb exercise. However, FES was reported to have two main problem that are the excessive muscle fatigue during prolonged stimulation and inadequate control of required electrical stimulation. This paper describes the design of a FES knee exercise used to reduce muscle fatigue during prolonged FES induced knee exercise. Paralyzed knee trajectories are measured using electro-goniometers as a feedback for the controller. In order to regulate the right electrical stimulation, a PID control scheme had been introduced. PSO and GA are used to optimize the PID parameters and the performance of swinging exercise are compared with the manually tuned PID parameters. Results shows that the GA tuned PID have improved the quality of knee swinging exercise if compared with the PSO and manually tuned PID.