High precision positioning of table drive systems using strain feedback

This paper presents a control methodology for high precision positioning of table drive systems. In the controller design, effects of resonant vibration modes and nonlinear friction on the positioning performance should be carefully considered. In order to compensate for the friction, it is essential to improve the disturbance suppression characteristic by expanding the bandwidth of feedback controller. Although the feedback control with a disturbance observer is one of promising approach to expand it, the vibration modes restrict the expansion due to their phase characteristics. In this paper, therefore, a robust compensator for the vibration modes is designed by a feedback scheme using a vibration signal of the modes, where a piezoelectric element is used to directly detect the signal as a strain signal corresponding to the mechanical deformation. As a result, the expansion of disturbance observer bandwidth can be achieved. The proposed approach has been verified by experiments using a prototype for industrial table positioning devices.