Western Digital Technologies, Inc.

Seagate Technology Incorporated

Orhan Beker

Mingji Lou

Kexiu Liu

Yanan Huang

Duc T Phan

Alexander Babinski

Alain Chahwan

Chuanwen Ji

Jenghung Chen

Jeffrey Vincent DeRosa

Aswartha Narayana

Xiuli Guo

Lu Feng

Daniel Lee Helmick

George J Bennett

Chun Sei Tsai

Wei Xi

Donald Joseph Brunnett

Min Chen

Carl E Barlow

Kenny T Coker

Hien T Chu

Shan Tang

Jack Allen Mobley

Nathan J Santee

Kenneth T Tabacchi

Wenlin Zhang

Shane Walker

Yiqian Li

Xiao Ma

Charles D Richards

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks. An operating seek time profile is generated as a function of a base seek time profile, wherein the seek time profiles define a seek time to seek the head radially over the disk by a seek length. A seek operation is executed to seek the head by a target seek length by at least generating a target seek time based on the target seek length and the operating seek time profile, and seeking the head the target seek length based on the target seek time.

Data storage device generating an operating seek time profile as a function of a base seek time profile

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by servo sectors, wherein each servo sector comprises a plurality of servo bursts and the servo sectors define a plurality of servo wedges. A first write operation is executed to a first track and a first absolute position for the head is generated corresponding to a first servo wedge. A second write operation is executed to a second track and a second absolute position for the head is generated corresponding to the first servo wedge. An off-track write condition is detected when executing the second write operation based on the first absolute position and the second absolute position. The first absolute position comprises a track address of the first track and a position error measurement based on the servo bursts in the first servo wedge.

Data storage device saving absolute position at each servo wedge for previous write operations

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks, wherein at least two of the tracks comprise a thermal asperity. Prior to seeking the head from a first track to a second track, for each of at least two of the thermal asperities a minimum seek delay and a maximum seek delay that will cause the head to miss the thermal asperity are computed, and an allowed seek delay range that will cause the head to miss the thermal asperity is computed. When the undelayed seek will cause the head to hit at least one thermal asperity, the seek is delayed by a seek delay determined based on the minimum seek delays, the maximum seek delays, and the allowed seek delay ranges.

Data storage device delaying seek operation to avoid thermal asperities

A data storage device is disclosed comprising a disk comprising a plurality of tracks, and an actuator configured to actuate a head over the disk. While seeking the head from a first track toward a second track, a velocity of the head over the disk is measured, and a deceleration distance and a deceleration time is generated based on the measured velocity. A coast velocity is generated based on the measured velocity, the deceleration distance, and the deceleration time, and a control signal applied to the actuator is adjusted based on the measured velocity and the coast velocity.

Data storage device dynamically reducing coast velocity during seek to reduce power consumption

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks, and a load/unload ramp. When seeking the head a seek length from a starting track to an ending track, control circuit is configured to adjust a seek profile when the seek length is greater than a first threshold and the ending track is within a second threshold of the load/unload ramp.

Data storage device adjusting seek profile based on seek length when ending track is near ramp

A method of operating a disk drive is disclosed, the disk drive comprising a disk comprising a plurality of tracks, and a closed loop servo system comprising a seek servo loop and a settle servo loop for actuating the head over the disk, the settle servo loop comprising a feed-forward compensator. The seek servo loop seeks the head toward a target track, and when the head approaches the target track a state trajectory of the feed-forward compensator is initialized with an initial value in response to a measured state of the servo system. The settle servo loop then settles the head on the target track in response to a feed-forward compensation generated by the feed-forward compensator.

Disk drive employing model-based feed-forward compensation during seek settling

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 disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The head is loaded over the disk during a load operation, and a radial velocity of the head is determined during the load operation. A target track is generated based on the determined radial velocity of the head, and the servo control system seeks the head to the target track.

Disk drive minimizing initial seek distance after load operation

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks, wherein each track comprises a plurality of servo sectors. When entering an idle mode, the head is floated over the disk, and when exiting the idle mode, a radial velocity of the head is measured, a seek distance is determined in response to the radial velocity, and a seek operation seeks the head the seek distance to a first track.

Reducing acoustic noise in a disk drive when exiting idle mode

A data storage device is disclosed comprising a disk comprising a plurality of tracks defined by servo sectors, a head, and a servo controller configured to servo the head over the disk based on an estimated state generated by a state estimator. The servo controller is configured to execute a seek operation to seek the head over the disk and recover from a servo fault during the seek operation by generating an initial state estimate of the head at the beginning of the servo fault, and decelerating the head open-loop using a model-based deceleration control in response to the initial state estimate. While decelerating the head, the state estimator is re-qualified before the head reaches zero velocity, and after re-qualifying the state estimator and before the head reaches zero velocity, a seek operation is executed to seek the head to a target track closed-loop using the state estimator.

Data storage device re-qualifying state estimator while decelerating head

A method of operating a disk drive is disclosed wherein the disk drive comprises a disk comprising a plurality of tracks, a head, and a closed loop servo system comprising a seek servo loop and a settle servo loop for actuating the head over the disk. When the head approaches a target track during a seek operation, the settle servo loop is enabled wherein a feedback control signal is generated based on a measured state of the servo system. The feedback control signal is adjusted with a feed-forward compensation. A phase shift between the measured state of the servo system and a corresponding estimated state of the servo system is compensated. The head is settled on the target track in response to the feed-forward compensation.

Disk drive employing feed-forward compensation and phase shift compensation during seek settling

A disk drive is disclosed comprising a head actuated over a disk, and control circuitry including a vibration sensor. A position error signal (PES) is generated representing a radial location of the head over the disk, and the head is servoed radially over the disk in response to the PES. A first vibration signal is generated in response to the vibration sensor, and a second vibration signal in response to the PES. The first vibration signal is combined with the second vibration signal to generate a third vibration signal, and a vibration event is detected in response to the third vibration signal.

Disk drive evaluating multiple vibration sensor outputs to enable write-protection

A disk drive is disclosed wherein N data wedges of write data are buffered in a buffer. After writing at least two of the data wedges to the disk including a first data wedge and a second data wedge, a first servo metric value is measured when reading a first servo sector, and a second servo metric value is predicted based on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector. When the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, the first data wedge is released from the buffer, and when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, the first and second data wedges are released from the buffer.

Disk drive releasing variable amount of buffered write data based on sliding window of predicted servo quality

A data storage device is disclosed comprising a disk comprising a plurality of tracks, a head, and an actuator configured to actuate the head over the disk. An adjusted seek time is determined to seek the head from a first track to a second track, and an adjusted coast velocity and an adjusted coast time of the seek is determined based on the adjusted seek time and a power consumption of the seek when a driving current applied to the actuator is substantially constant during at least one of an acceleration time and a deceleration time of the seek.

Data storage device reducing seek power consumption

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks, and control circuitry operable to seek the head to a target track and settle the head on the target track during a settle time, adapt a settle parameter over an adapting delay of the settle time, wherein the settle parameter is used to settle the head on the target track, and decrease the adapting delay based on a speed that the settle parameter adapts.

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Dove Canyon, CA, United States of America

Orhan Beker