High-precision positioning considering suppression of resonant vibration modes by strain feedback

This paper presents a control methodology for high-precision positioning system. In order to realize the high-precision in positioning, the expansion of servo bandwidth is one of the promising approaches. However, since most of mechanisms inherently include mechanical vibration modes around the control response frequency, the control bandwidth is restricted by the resonant frequency. In order to provide the precise positioning performance, therefore, it is indispensable to suppress the mechanical vibration modes. In addition, the controller should be designed to achieve the robust properties against the frequency variations in the vibration modes. In this paper, a robust positioning system is designed by a feedback compensator using a direct signal of vibration modes, where a piezoelectric element is used to detect the vibration signal as a strain signal due to the plant deformation. The proposed approach has been verified by experiments using a positioning device for galvano scanners.