FAT based Adaptive Control for a Lower Extremity Rehabilitation Device: Simulation Results

This paper concerns the control of a newly developed wearable lower extremity rehabilitation device intended to aid stroke patients who are in early phase of rehabilitation or severely affected. The device adopts an anthropomorphic structure actuated on hip and knee joint level in sagittal plane. The device and wearer system is modelled as a simplified two degree of freedom robotic structure with the wearer to be completely passive. Fourier series fitting method is used to obtain the desired hip and knee reference trajectory. Function Approximation Techniques (FAT) based adaptive control strategy is adopted and applied to track the desired gait trajectory. Simulation results show that good tracking performance is achieved, and actuator toques are within a reasonable range. This FAT based adaptive control algorithm could potentially be used in real-time applications.