Adaptive command-filtered control for nonlinear systems with actuator faults and unknown control directions

This paper focuses on the issue of adaptive fuzzy control for nonlinear systems with actuator faults and unknown control directions. Command filtering techniques are integrated with the Nussbaum function to address the issue of complexity explosion and to compensate for the effects of unknown control directions. This approach effectively compensates for filtering errors. In the presence of actuator faults and disturbances, an actuator fault compensation auxiliary system is designed to resolve the signal mismatch between the controller and the actuator. By utilizing Lyapunov stability theory and backstepping control methods, it is proven that the tracking error can ultimately converge to a small neighborhood near the origin. Furthermore, in accordance with the control design, all signals within the system remain bounded. Finally, the effectiveness of this control strategy can be validated through simulations of a circuit containing a nonlinear controlled source and nonlinear pendulum model.