Double Feedforward Control System Based on Precise Disturbance Modeling for Optical Disk

Abstract

Optical disk drive systems must realize high-precision tracking control for their proper operation. For this purpose, we previously proposed a tracking control system that is composed of a high-gain servo controller (HGSC) and a feedforward controller with an equivalent-perfect tracking control (E-PTC) system. However, it is difficult to design the control parameter for actual multi-harmonic disturbances. In this paper, we propose a precise disturbance model of an actual optical disk using the experimental spectrum data of a feedback controller and describe the design of a fine tracking control system. In addition, we propose a double feedforward control (DFFC) system for further high-precision control. The proposed DFFC system is constructed using two zero phase error tracking (ZPET) control systems based on error prediction and trajectory command prediction. Our experimental results confirm that the proposed system effectively suppresses the tracking error at 6000 rpm, which is the disk rotation speed of Digital Versatile Disk Recordable (DVD+R).