Robust feedforward track following control system for an optical disk

This paper proposes a new robust feedforward tracking servo system for optical disk recording system based on prediction of tracking error. In optical disk recording systems, its detecting signal is only a tracking error. The tracking servo system, such as CD-R, must have a complete tracking response whose error is less than 0.1 μm for amplitude of 100 μm of position reference. For this purpose, this paper proposes a new tracking servo system based on the prediction of the tracking error. The proposed robust feedforward tracking control system is constructed by both a "zero phase error tracking" (ZPET) control system and a robust feedback control system. Moreover, this paper considers the saturation of the controller output. The experimental and numerical simulation results point out that the proposed system has a quick and precise tracking response and keeps the residual tracking error below this tolerance smoothly and stably.