Design and control of tracking actuator for optical disk

In an optical disk system, a tracking system consists of a coarse actuator and a fine tracking actuator. The double actuality system requires many devices in order to obtain large strokes and precise displacement simultaneously. Moreover the moving parts become sophisticated because of the complicated configuration. In this paper a new one-dimensional tracking actuator combining a fine tracking actuator and a coarse actuator is designed. The voice coil motor is used as a basic drive mechanism. The permeance method is used to analyze and to design VCM for large driving forces and its characteristic is tested through experiments. The focus spring is designed in terms of the stability and characteristics of the system. Since friction is a dominant error source, friction identification is carried out. The designed actuator shows its ability to resolve a motion less than 0.1 μm