Adaptive controller based on uncertainty parametric estimation using backstepping and sliding mode techniques: Application to an active orthosis

In this paper we propose an adaptive controller based on sliding mode and backstepping approaches. The system to be controlled is an exoskeleton used for the rehabilitation of the knee joint. The person wearing the exoskeleton is healthy, sitting and performs movements of flexion/extension. This kind of movement is usually applied by the doctor. The parameters of the dynamic model of the overall system (knee & exoskeleton) are considered unknown. The proposed controller is stable and robust against bounded external disturbances. The experimental results show the effectiveness of the proposed approach. The tests have also been validated when the wearer applies a resistive/assistive torque.