Dynamic investigation and adaptive tracking-error improvement of optical disk drives

The ignorant action to stick labels on optical disks for noting can make a severe imbalance problem. The study investigates the dynamic characteristics of a rotating optical disk at a varying speed through vibro-acoustic excitation. The. disk imbalancing modulated with its resonant frequencies can be evidently observed by computed spectrograms. Then vibration disturbance at the critical speed is interpreted. Reductions on tracking errors and improvement on tracking performance are performed. An adaptive feedforward cancellation (AFC) scheme associated with the existing tracking servo through the feedback controller is implemented to cancel the disturbance effectively. Experimental results show the AFC apparently suppresses the tracking errors arising from the imbalancing of rotating disks.