Western Digital Technologies, Inc.

Qixing Zheng

Min Chen

Duc T Phan

Alain Chahwan

Alexander Babinski

James V Wiseman

Shang-Chen Wu

A disk drive comprises a track follow control system having a plurality of selectable frequency modes, the track follow control system configured to receive a position error signal and to output a control signal based on the position error signal, wherein the control signal is used by a head assembly to position a head over a disk. The disk drive also comprises a state estimator configured to receive the control signal and a position signal indicating a position of the head, to estimate a disturbance based on the control signal and the position signal, and to output an estimated disturbance signal based on the estimated disturbance. The disk drive further comprises a disturbance evaluator configured to receive the estimated disturbance signal, and to select one of the frequency modes of the track follow control system based on the estimated disturbance signal.

Adaptive track follow control

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors that define a plurality of servo tracks. The servo sectors comprise a plurality of servo bursts including a first servo burst, a second servo burst following the first servo burst and offset radially by approximately one half of a servo track from the first servo burst, a third servo burst following the second servo burst and offset radially by approximately one full servo track from the second servo burst, and a fourth servo burst following the third servo burst and offset radially by approximately one half of a servo track from the third servo burst. A PES is generated form the servo bursts that is substantially insensitive to a radial velocity of the head.

Disk drive employing velocity insensitive servo burst pattern

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors that define a plurality of servo tracks. A position error signal (PES) is generated in response to the servo sectors, and a head velocity is estimated relative to the servo tracks. A correction value is generated as a function of the head velocity and the PES, and the PES is adjusted using the correction value to generate an adjusted PES. The head is positioned over the disk in response to the adjusted PES.

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Albany, CA, United States of America

Qixing Zheng