Western Digital Technologies, Inc.

Western Digital Corporation

Western Digital (Singapore) Pte. Ltd.

David B Joan

Richard William Hull

Jie Yu

Vafa James Rakshani

Charles Royston Patton, Iii

Michael R Spaur

Charles W Simmons

Takashi Asami

Robert P Mento

Marshall D Lee

Min-Hui Wang

A method of tuning a servo control system in a disk drive that implements seeks using a the feed-forward command effort signal u and a PES reference signal r that were designed to be compatible with one another on the basis of a modeled frequency response G (z) that is different from an actual frequency response G(z). The steps includes scaling the feed-forward command effort signal u to substantially achieve a zero velocity condition at an end of the seek; scaling the feed-forward command effort signal u to substantially achieve an on-target condition at the end of the seek; and modifying the PES reference signal r such that it substantially varies in unison with the indicated PES signal y during the seek

Method of tuning feed-forward control in a disk drive

A disk drive controller having a microprocessor and a sampled signal head positioning system measures and stores the relative rotational offsets between heads arranged in a stacked relationship and respective servo wedges on different disk surfaces. The offsets are stored in a table and subsequently applied to a servo wedge detection circuit to ensure that a next sequential wedge is detected after a head switch.

Method and apparatus to compensate for servo wedge rotational offset

An integrated servo system for a disk drive employing sector servo positioning information on concentric tracks of a recording medium utilizes a servo burst pattern with three sequentially occurring servo bursts. One burst is positioned to have a maximum amplitude plateau on a track centerline of alternate tracks, and the other two bursts have maximum plateau values at locations between the centerlines of adjacent tracks. The amplitudes of the bursts are sequentially detected by a peak detector and supplied to sample and hold circuitry for measuring their relative amplitudes. Discriminator circuitry utilizes a window to provide two samples of each transition in the servo pattern and compares the samples to detect different fields and events in the pattern.

Information detecting system

Growing community of inventors

Trabuco Canyon, CA, United States of America

David B Joan