Adaptive output-feedback control design with prescribed performance for switched nonlinear systems

In this paper, an output feedback control method with prescribed performance is proposed for single-input and single-output (SISO) switched non-strict-feedback nonlinear systems. It is assumed that nonlinear functions of the concerned systems are unknown, switching signals are unknown and arbitrary, and the states are unmeasured. A linear state observer is designed to estimate the unmeasured states, and an observer-based output feedback control scheme is developed. The key advantages of the proposed control strategy are that virtual control gains of the concerned non-strict-feedback nonlinear systems are not required to be known, and only one tuning parameter is needed. Based on Lyapunov stability theory, it is shown that all the signals in the resulting closed-loop system are semi-globally uniformly ultimately bounded, and the tracking error converges to a small residual set with the prescribed performance bound. The effectiveness of the proposed control approach is verified by a numerical example.