A pickup system for optical disks operates in the horizontal and vertical directions for tracking and focusing, respectively. The conventional optical disk system is designed for each direction of operation. The conventional system becomes slow in moving to the next point because it does not consider the operation trajectory. Thus, because the point-to-point movement becomes longer, there is possibility that the tracking performance is deteriorated in high-speed rotation. In order to achieve faster operation, we develop a concurrent control method of tracking and focusing on an optical disk and realize short trajectory control. In this paper, a new two-dimensional feedforward control system is proposed, which has concurrent control of focusing and tracking. The feedforward controller is based on equivalent-perfect tracking control (E-PTC). The experimental results show the effectiveness of the proposed control system.
2015 The Institute of Electrical Engineers of Japan