Patent ID: 6538839
Filing Date: 2003-03-25
Classification: G11B

Abstract:
A disk drive comprising:(a) a disk comprising a plurality of tracks; (b) a head; (c) an actuator, responsive to an adjusted control effort signal, for actuating the head radially over the disk; (d) a servo control system for generating the adjusted control effort signal, the servo control system comprising; a position error generator for generating a position error signal indicative of the head's position with respect to a centerline of a selected track; a servo compensator, responsive to the PES, for generating a nominal control effort signal; a sensor for sensing a vibration affecting the disk drive to generate a sensor signal; an adaptive vibration compensator, response to the sensor signal, for generating a feed-forward signal; and a signal generator for combining the nominal control effort signal with the feed-forward signal to generate the adjusted control effort signal applied to the actuator, wherein: during a normal read operation the adaptive compensator is disabled to substantially remove the contribution of the feed-forward signal from the adjusted control effort signal; and during a retry read operation the adaptive compensator is enabled to include the contribution of the feed-forward signal in the adjusted control effort signal.