Western Digital Technologies, Inc.

Shan Tang

Duc T Phan

Chuanwen Ji

Yanan Huang

Wei Xi

Orhan Beker

Alain Chahwan

Min Chen

Jianguo Zhou

Alexander Babinski

Hengchang Guo

Zhenyu Zhang

Lu Feng

Jianjun Li

A data storage device is disclosed comprising a head actuated over a disk surface comprising tracks defined by servo sectors, wherein each servo sector comprises at least one servo burst comprising a periodic pattern. The servo burst of one of the servo sectors is read to generate a read signal, and M intermediate integration points yare computed according to: where r(kT) represents a sample point of the read signal, Trepresents a sample interval between the sample points, and &#x3c9; represents a frequency of the periodic pattern in the servo burst.

Data storage device demodulating servo burst by computing slope of intermediate integration points

A disk drive is disclosed comprising a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors, and an actuator for actuating a head over the disk in response to an actuator control signal. The servo sectors are read to generate a first sequence of control samples x[k] at a sample frequency corresponding to a frequency of the servo sectors. A hybrid upsample filter is used to upsample by a factor of N the first sequence of control samples x[k] to generate a second sequence of control samples y[k], wherein the hybrid upsample filter provides a higher phase gain than a zero-order type upsample filter at frequencies less than one kilohertz, and approximately the same attenuation as a first-order type upsample filter around the sample frequency. The actuator control signal is generated in response to the second sequence of control samples y[k].

Disk drive servo control using hybrid upsample filter

A disk drive is disclosed comprising, a head, a disk surface, and a dual stage actuator (DSA) servo loop comprising a voice coil motor (VCM) servo loop comprising a VCM and a microactuator servo loop comprising a microactuator operable to actuate the head over the disk surface. A frequency component of a servo signal in the DSA servo loop is evaluated, wherein the frequency component is based on a peak frequency of an error rejection curve of the DSA servo loop. A degradation of the microactuator is detected based on the frequency component of the servo signal.

Disk drive detecting microactuator degradation by evaluating frequency component of servo signal

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo sectors. The head is positioned over a first servo track, and a first position error signal (PES) by reading a first servo sector during a first revolution of the disk and in response to a first compensation value. A second compensation value is updated for a second servo sector based on the first PES during the first revolution of the disk. A second PES is generated by reading the second servo sector during the first revolution of the disk and in response to the updated second compensation value. The first compensation value is updated for the first servo sector based on the second PES during the first revolution of the disk. The head is actuated over the disk in response to the first PES and the second PES.

Disk drive updating compensation values for multiple servo sectors based on PES generated for current servo sector

A method of evaluating a dual stage actuator (DSA) servo loop in a disk drive is disclosed. The disk drive comprises a dual stage actuator (DSA) servo loop operable to actuate a head over a disk surface. A first sinusoidal signal Ais added to a VCM control signal Bgenerated by a VCM servo loop. A response of the VCM control signal Bto the first sinusoidal signal Ais measured, and a closed loop response of the VCM servo loop is computed in response to Aand B. A second sinusoidal signal Ais added to a microactuator control signal Bgenerated by a microactuator servo loop. A response of the microactuator control signal Bto the second sinusoidal signal Ais measured, and a closed loop response of the microactuator servo loop is computed in response to Aand B

Evaluating dual stage actuator response in a disk drive by adding sinusoid to control signal

A disk drive is disclosed comprising a disk surface, a head coupled to a distal end of an actuator arm, and a dual stage actuator (DSA) servo loop comprising a voice coil motor (VCM) servo loop and a microactuator servo loop operable to actuate the head over the disk surface. The microactuator servo loop is disabled, and after disabling the microactuator servo loop a sinusoid is injected into the VCM servo loop, wherein the sinusoid comprises a target frequency. A first open loop response of the VCM servo loop is computed. The microactuator servo loop is enabled, and after enabling the microactuator servo loop the sinusoid is injected into the DSA servo loop. A second open loop response of the DSA servo loop is computed. A microactuator servo loop gain and a VCM servo loop gain are tuned in response to the first and second open loop responses.

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Irvine, CA, United States of America

Shan Tang