Output Constrained Fault-Tolerant Control of Underactuated System Based on Extended State Observer

In order to address actuator faults in an underactuated system, a fault-tolerant control strategy based on extended state observer is proposed. The extended state observer is designed to estimate the actuator fault information. With the estimated fault value, a fault-tolerant controller is developed to accomplish position tracking, where the position error of the system is confined within a specified range by a strictly monotonically decreasing constraint function. The stability of the closed-loop system and the convergence of position tracking are proved by Lyapunov theory. The effectiveness of the proposed method is validated through comparative simulations. The proposed approach not only compensates for the impact of actuator faults on underactuated system but also ensures rapid convergence of position error, keeping it within the prescribed constraints.