Minimum trajectory control of focusing and tracking of optical disk systems by two-dimensional feedforward compensator

Pickup systems for optical disks operate in the horizontal and vertical directions for tracking and focusing, respectively. Conventional optical disk control systems are designed for each operated direction. On the other hand, in this paper, we consider the operation trajectory to implement a method for concurrent control of focusing and tracking of optical disks. This paper proposes a two-dimensional feedforward control system. The proposed control system consists of a feedforward controller and a two-dimensional feedforward compensator. The error vector is a combination of the focusing error and the tracking error of the compensator. The feedforward controller based on a zero phase error tracking control (ZPETC) regulates the error vector. The experimental results show the effectiveness of the proposed control system.