Fault-Estimation-Based Output-Feedback Adaptive FTC for Uncertain Nonlinear Systems With Actuator Faults

This paper investigates the adaptive output-feedback fault-tolerant control (FTC) problem for a class of uncertain nonlinear pure-feedback systems subject to actuator faults. To address the challenges incurred by the actuator faults and unmeasured state, a novel fault compensation observer-based adaptive controller is designed by estimating fault parameters online. By combining the backstepping design framework with prescribed performance and command filters techniques, it is proved that the proposed FTC scheme guarantees that all the signals in the closed-loop system are bounded and that the tracking error remains within the predefined bounds even if actuator faults occur. Compared with the existing output-feedback FTC design methods, the compensation state observer removes the restriction that the fault parameters are known or the uncontrollability caused by input saturation. The simulation and experimental results verify the effectiveness of the proposed method.