Optical disk drives are spotlighted data storaging devices. In order to increase the data transfer rate, the rotational speed of disk has been increased. In the meantime, direct seek control schemes were developed to reduce data access time. However, conventional direct seek control schemes are not appropriate to the high-speed rotational disk drives owing to increase of the eccentric rotational velocity. In general, the conventional seek algorithm is a two-stage seek method composed of coarse seek and fine seek. The fine actuator has a feature of high acceleration while the range of the fine seek is restricted within one hundred tracks because of the risk of misalignment of objective lens with beam axis. Thus, the seek time for hundreds of tracks can be reduced by extending the range of fine seek. In this thesis, a new direct seek control scheme for hundreds of tracks is proposed. The fine actuator is controlled to follow a given reference velocity trajectory of the lasor spot with high acceleration. Moreover, the coarse actuator aligns the beam axis with the objective lens to detect the position and velocity of lasor spot. To confirm the feasibility of the proposed scheme, it is applied to a CD-ROM drive and the experimental results are compared with those of conventional seek method.
