Double-Boosted High-Gain Servo Controller for High-Rotation-Speed Optical Disk Drives

We propose the use of a double-boosted high-gain servo controller for high-rotation-speed optical disk drives. This controller consists of two low-frequency boosters and a lead-lag compensator. Additionally, we use a pole-placement method to design parameters of the controller to obtain the highest low-frequency gain. This controller increases low-frequency gain extremely without decrease in phase margin. We applied this controller to a tracking servo system of an experimental optical disk drive based on a Blu-ray disk drive, and confirmed the decrease in residual tracking error to only 22%. Furthermore, the rotational speed reaches 14500 rpm on an inner track of a disc (r=25 mm).