Fault estimator-based dynamic surface backstepping fault-tolerant control for a class of nonlinear systems with output constraint

Aiming at the tracking control problem of a class of nonlinear systems with actuator fault and external disturbance, a dynamic surface backstepping control method is proposed based on a fault estimator in this paper. First, the actuator fault and external disturbance of the systems are treated as a lumped actuator fault disturbance term, and a fault estimator is designed to address this issue. Next, a prescribed performance function is introduced to manage output constraint, even in the presence of entirely unknown initial tracking conditions. The dynamic surface control technique is introduced to address the issue of “differential explosion” in conventional backstepping control and simplify the design process of system controller. Theoretical analysis demonstrates that the closed-loop system exhibits uniformly ultimately bounded stability, and the output remains within the specified bound. Finally, the effectiveness of the proposed method was validated using the position tracking control of a permanent magnet synchronous motor as an example.