Event-based Adaptive Output Feedback Prescribed Performance Control for a Class of Switched Nonlinear Systems with Unknown Control Directions

An event-triggered adaptive tracking control problem is investigated for a class of switched nonstrictfeedback nonlinear systems with unknown control directions and switching signals. With a linear observer, the output feedback stabilization is achieved under arbitrary switching. The key advantages of the proposed control strategy are that the tracking prescribed performance is ensured regardless of the unknown control directions. Only one tuning parameter needs to be estimated during the recursive process. Moreover, with a varying threshold, a common event-triggered mechanism is developed. Based on the Lyapunov stability theory and the dynamic surface backstepping technique, the developed control method theoretically proves that under arbitrary switching, all signals of the resulting closed-loop switched system are bounded and the tracking error can converge to a small neighborhood of the origin within the prescribed bounds. The Zeno behavior is also avoided. The effectiveness and feasibility are demonstrated by two examples.