Position tracking control of an optical pick-up device using piezoceramic actuator

Abstract

This paper proposes a piezoactuator-driven optical pick-up for compact disc-read only memory (CD-ROM) drive in order to achieve fine motion control of objective lens. The dynamic model of the proposed optical pick-up consisting of piezoceramic bimorph, wire suspension and objective lens is derived from Hamilton’s principle. A state-space control model is subsequently formulated by considering hysteresis behavior of the piezoactuator and frequency variation of the device as uncertainties. A sliding-mode controller, which is known to be robust to system uncertainties is designed for fine motion tracking control of the objective lens in vertical direction (focusing). The controller is then experimentally realized and position-tracking responses of the optical pick-up are presented in time domain. In addition, control durability is demonstrated by showing favorable tracking performance of a sinusoidal trajectory up to 8000 cycles of operation.