304 Head Positioning Control System for High-Density Recording of Next Generation Optical Disk Drives

Abstract

In the optical head servos of optical units, the restraint of vibration, both from the head itself and from external disturbances has become an important technical issue. In this paper, we introduce a hybrid control method that combines the use of an external disturbance observer with that of a VSS(Variable Structure System) controller for the purpose of restraining vibration, and we show that this method results in reduction of actuator displacement to 75% of that achieved with previous methods.