Circle Condition-Based Robust Feedback Control Against Plant Perturbation

This paper presents a novel robust feedback (FB) controller design against plant perturbation for the fast and precise motion control of high-precision servo systems. The plant perturbation, e.g., parameter fluctuation and uncertainties, due to temperature variation and/or aged deterioration generally deteriorates the motion performance as well as the system stability. Balancing a trade-off between expansion of the control bandwidth and the stability, therefore, is a general and important index in the FB controller design to provide robust properties against the perturbation. In this study, a circle condition-based robust FB controller design considering the robust stability and the robust sensitivity is proposed to achieve the improved motion control performance. Effectiveness of the proposed approach has been verified by numerical simulations for a galvano scanner.