Abstract
This paper presents a control design methodology for high-precision positioning; in particular, the compensation for the effects of vibration modes and nonlinear friction on the positioning performance is taken into account in this methodology. In the controller design, the servo bandwidth of the feedback control loop should be expanded to compensate for the nonlinear friction, while robust stability against frequency variations in the vibration modes should be ensured. In this study, therefore, a strain feedback for vibration modes is adopted to provide robustness against the frequency variations and to improve the disturbance suppression performance by expanding the bandwidth of a disturbance observer; this strain feedback is based on the use of a piezoelectric element. The efficacy of the proposed positioning control approach has been verified by conducting experiments using a prototype for industrial table drive systems.
