ADRC-Based Trajectory Tracking Control for a Planar Continuum Robot

Due to their inherent deformability, controlling continuum robots (CRs) comes with many challenges, including strong nonlinearity, uncertainty, and disturbance. In this paper, a planar CR is modeled as a general multi-input multi-output (MIMO) system with internal uncertainty and external disturbance. To improve the trajectory tracking performance, an active disturbance rejection control (ADRC)-based control strategy for the CR is proposed. The proposed method can regard the internal uncertainty and external disturbance of the CR as an overall disturbance. In the ADRC framework, a linear extended state observer (ESO) is designed to timely estimate the overall disturbance, and a closed-loop control with disturbance compensation and feedback control law is implemented. The convergence of the designed ESO and the stability of the ADRC-based controller are studied. Simulations and experiments are performed to verify the effectiveness of the proposed approach.