A feedback controller design based on circle condition for improvement of disturbance suppression

This paper presents a novel feedback (FB) controller design methodology for the fast and precise positioning of mechatronic systems. Improvement of the disturbance suppression performance is a general and important index in the FB controller design to realize the precision performance. However, since the stability of the FB system generally limits the disturbance suppression capability, improvement of both the disturbance suppression and the stability should be difficult to achieve. In this study, therefore, a FB controller which considers the stability margins (i.e. gain and phase margins) is designed on the basis of a circle condition on the nyquist diagram, to achieve the required disturbance suppression with the desired stability margins. Effectiveness of the proposed approach has been verified by numerical simulations and experiments using a prototype of linear motor-driven table systems.