H/sub /spl infin// proportional integral observer for switched systems

This paper concerns the designation of H _∞ proportional and integral observer (Pi-observer) for switched systems under arbitrary switching sequences. Based on the Lyapunov stable rule, we detect the existence of a switched quadratic Lyapunov function which can guarantee the asymptotic stability of switched systems. Through some analysis, two equivalent conditions are developed, which can guarantee the Pi-observer to track the state. At last, a numerical evaluation illustrates the feasibility and advantage of Pi-observer for switched systems.