Optimal impedance control for robot-aided rehabilitation of walking based on estimation of patient behavior

Abstract

This paper deals with optimal impedance control of robotic devices designed for rehabilitation of walking after stroke. The proposed optimal solution is based on the estimation of torque and impedance parameters of the patient during the gait. The patient's torque is estimated using the generalized momenta-based disturbance observer associated with the Kalman filter algorithm. The stiffness and damping parameters are determined by the least square method, considering that the patient motor control is modeled as an impedance control, with a predefined gait-pattern as the desired trajectory of the joints. An optimization procedure is then performed after each step to tune the impedance parameters of the actuators' controller for the next step. In order to validate the proposed approach, simulation results considering a patient wearing an active hip/knee/ankle orthosis is presented, where several patient and robot conditions are evaluated for a set of steps.