Adaptive Fault-tolerant Control for Mechanical Manipulator Systems with Actuator Fault

In this paper, the tracking control problem of a class of mechanical manipulator system with actuator fault and mismatched disturbance is investigated. An observer-based adaptive fast finite-time sliding mode fault-tolerant control (OB-AFTSMFTC) scheme is proposed. Firstly, a novel composite observer is designed to estimate the state, fault efficiency factor, and disturbance simultaneously without the disturbance bound information. It is theoretically proved that the entire observer system is globally stable. To address the tracking performance, the Euler's discretization technique is applied to approximate the discrete-time tracking error model. Subsequently, an OB-AFTSMFTC strategy is proposed based on the tracking error. In the proposed control scheme, two adaptive parameters are designed to realize the autonomous adjustment of controller parameters, thus the work of parameter adjustment can be reduced and a faster convergence can be achieved. Furthermore, the estimated disturbance information is utilized to construct the sliding mode controller in order to improve the robustness of the tracking performance. Finally, two simulation cases are carried out to verify the fault tolerance ability of the proposed method.