Robust servosystem design by using PIA

This paper is concerned with the robust controller design problem. The design method is based on the gain-phase shaping approach, and it represents and treats uncertainty of frequency response of plant using the polygon interval arithmetic (PIA) method. In the framework of both 1 degree of freedom (1-DOF) and 2-DOF servosystems, we design controllers which satisfy: 1) robust stability, 2) input response characteristics (bandwidth, nonresonance property, or specific resonant peak property), 3) the sensor noise suppression characteristic, and 4) the disturbance suppression characteristic. To demonstrate the usefulness of the proposed method, an example of designing current loop controller for velocity control systems of DC motor is shown. It is noted that the proposed method guarantee the worst case performance, which is particularly important in the nonresonance property