Dynamic Eccentric Error Compensation for Track Following Control of Optical Disk Driver

For obtaining a good tracking performance in an optical disk drive servo system, it is essential to attenuate periodic disturbances caused by eccentric rotation of the disk. This paper proposes a dynamic eccentric error compensation scheme for optical disk drivers to track a periodic reference signal with dynamic change in period. Periodic disturbances can be attenuated using a sinusoidal generator with the known disturbance frequency provided by a motor driver. Optical disk drivers support various speeds. So optical disk drivers have a varying periodic disturbance. To deal with time varying periodic disturbances, a proposed dynamic eccentric error compensation controller is turned based on sinusoidal generator to follow the change of reference period. The sinusoidal generator uses the discrete Fourier transform (DFT) method that models the periodic disturbance. Simulative and experimental results show that the proposed control scheme enables a significant improvement of the tracking accuracy of the radial servomechanism and the random access time.