Robust control system with observer

Abstract

This paper proposes a design method for a robust controller including a state observer. Though the optimal regulator has often been used as a desirable controller, it is not necessarily robust if it includes a state observer whose input uses the plant input as well as the plant output. Some attempts to recover robustness have been reported, but perfect robustness has not been achieved. Our method is based on the principle that the return difference is made to satisfy the circle condition for the system to remain robust, and the response properties are improved by the extended perfect model-following system. Design examples are given, and the responses of the designed systems are simulated to exemplify the effectiveness of our method.