Improved Active Disturbance Rejection Control for the Knee Joint Motion Model

Abstract

This work focuses on design of trajectory-tracking control based on active disturbance rejection control (ADRC) controller for knee joint exoskeleton device. The device is worn by disable patients and it is actuated by ADRC to perform the exercises prescribed by physician doctor for rehabilitation of humanoid's lower limb. In order to improve the tracking performance and robustness characteristics of ADRC, minor modification has been made in its structure, which is represented by adding feed forward control signal to reference angular acceleration. The numerical simulations via MATLAB software environment have been conducted with various model uncertainties and external disturbances to assess the performance of modified control scheme. The proposed controller showed improvement in trajectory tracking error, rejection of exerted disturbances, and robustness against parameter uncertainties