High-Gain Servo Controller for Optical Disk Drives and the Initial Value Compensation

As optical disks are removable and have some distortions, servo systems of optical disk drives must be robust, especially at low frequency. We proposed the high-gain servo controller with complex zeros, which is the same 2 order controller as conventional controllers, and realizes a much higher gain at low frequency. Decrease of servo error was confirmed, but the controller increased overshoot of initial value responses. We also proposed applying the initial value compensation to suppress the overshoot.