Backstepping Active Disturbance Rejection Control for a 4 DoF Robot Manipulator Using High-Order Sliding Mode Extended State Observer

This paper proposes a new active disturbance rejection control (ADRC) strategy for robot manipulators operating under uncertainties, including unmodeled dynamics, parameter variations, and external disturbances. The goal is to accurately track desired trajectories while mitigating the effects of these uncertainties. The proposed ADRC framework utilizes a high-order sliding mode extended state observer (ESO) in conjunction with a backstepping control approach. This combination yields a robust control law that enhances accuracy. Firstly, the high-order sliding mode ESO is designed to estimate both the states and the total disturbance (extended state) of the robot manipulator system. Next, a backstepping control law is developed using the estimated states and disturbances to ensure effective trajectories tracking and compensate for uncertainties. The tracking performance and robustness of the proposed controller are validated through experiments conducted on a 4 degrees of freedom (4 DoF) MICO robot manipulator. The experimental results demonstrate that the proposed controller achieves superior tracking performance and disturbance rejection compared to the classical backstepping controller.