Summary
In this paper, a switched proportional integral observer (PIO) is designed for estimating the states and fault of sandwich systems with hysteresis. In the system, the actuator fault and sensor noise have been included simultaneously. The switched PIO contains a changeable transition matrix and a switched item, which can switch according to different working points of the hysteresis. The estimation errors of the states and fault are analyzed, and a theorem is given to illustrate the estimation errors of the states and fault, which are both bounded. The problem of selecting an appropriate feedback matrix of the switched PIO has been translated into an optimization problem with feedback matrix tuning. The effectiveness of the switched PIO has been testified in the simulation with a real application case. Moreover, to show the good performance of the switched PIO, a conventional PIO is proposed and compared in the simulation. The results show that the switched PIO is superior to the conventional one.