Adaptive compensation for actuator failure in a class of non-linear time-delay systems

This study presents a state feedback adaptive controller for a class of parametric-strict-feedback non-linear systems with multiple bounded time-varying state delays and in the presence of time-varying actuator failures. The type of the considered actuator failure is that some unknown inputs may be stuck at some unknown time-varying values where the parameters, times and patterns of the failures are also unknown. The considered actuator failure can cover most failures that may occur in actuators of the systems. The adaptive state feedback control scheme is constructed based on a backstepping design method. The boundedness of all the closed-loop signals is guaranteed and the tracking error is proved to converge to a small neighbourhood of the origin. The proposed approach is employed for a second-order time delay plant as well as a two-stage chemical reactor with delayed recycle streams. The simulation results show the correctness and effectiveness of the proposed adaptive compensation in the case of actuator failures.