Compensator design for a dual-stage actuator in the track-following control system of optical disk drives

In this paper, a compensator design method is presented for track-following control in an optical disk drive, a common mechanism for which is a dual-stage actuator composed of a fine and coarse actuator. Most of previous works, however, have focused on tracking precision enhancement using only the fine actuator without systematic design method for a coarse actuator compensator. As the dual-stage actuator is categorized as a dual-input single-output system, the overall stability is affected not only by the fine actuator but also by the coarse actuator. In addition, the coarse actuator compensator should satisfy a performance specification to prevent overall system failure. Based on some obvious differences in dynamic characteristics between the two actuators, two compensators can be designed independently. Then overall system stability is ensured by the designed compensators, and performance specifications are also satisfied. Validity of the design method is proved by some simulation and experiment.