Command filter-based adaptive fault-tolerant tracking control for switched nonlinear systems with time-varying output constraints

In this paper, the fault-tolerant tracking control problem is addressed for switched nonlinear systems subject to time-varying output constraints and dead-zone input under arbitrary switching signal. An improved output-dependent barrier function with weight factors is presented to handle the output constraint issue, which eliminates the conservative design that converts the output constraints into the tracking error related constraints and relaxes the requirements for the initial value of the systems output. Meanwhile, the barrier function presented in this paper can be used for the time-varying/constant symmetric/asymmetric output constraints and can tackle both constrained and unconstrained cases. Besides, the performance of the systems is ensured when actuator faults and dead-zone input occur simultaneously. By establishing the new coordinate transformations, together with command filter technique and the backstepping approach, the presented adaptive control strategy ensures that all signals of the closed-loop systems are bounded. Finally, the validity of the presented method is demonstrated via two simulation examples.