Western Digital Technologies, Inc.

Other

Jianguo Zhou

Wei Xi

Guoxiao Guo

Jie Yu

Alain Chahwan

Kuang-Yang Tu

Donald Joseph Brunnett

Dean Mitcham Jenkins

Lei Zhang

Wei Guo

Jun Xu

Abhishek Dhanda

Sanghoon Chu

David W Chew

Wai Ee Wong

Teddy T Chen

Feng Hong

Li Zhou

Masahito Kobayashi

Tetsuo Semba

Young-Hoon Kim

Min Chen

Hidehiko Numasato

Yiming Chen

Shan Tang

Xu Qi Chen

Hui Li

Eugene C Wu

Jianjun Li

Systems and methods are disclosed for providing secure access to a data storage device. A user may move the data storage device (e.g., wave, twist, etc.). The data storage device may determine whether the motions valid and may allow access to the data storage device (e.g., to non-volatile memory of the data storage device) when the motions are valid.

Data storage device with secure access based on motions of the data storage device

Systems and methods are disclosed for providing secure access to a data storage device. A user may provide tap inputs, such as taps or knocks, on an enclosure of the data storage device. The data storage device may determine whether the tap inputs are valid and may allow access to the data storage device (e.g., to non-volatile memory of the data storage device) when the tap inputs are valid.

Data storage device with secure access based on tap inputs

A data storage device is disclosed comprising an actuator configured to actuate a head over a disk surface, and a vibration sensor configured to generate a vibration signal (VS). Control circuitry comprising a servo control system having a torque rejection curve (TRC) configured to control the actuator is configured to measure a position error signal (PES) of the head, and measure the VS output by the vibration sensor. A feed-forward compensator is configured based on PES/VS/TRC. While seeking the head across the disk surface, the VS is processed using the feed-forward compensator to generate a feed-forward compensation during a settle interval of the seek, and the actuator is controlled using the feed-forward compensation during the settle interval.

Data storage device compensating for seek vibration using vibration sensor

A data storage device is disclosed comprising a first actuator configured to actuate a first head over a first disk surface, and a second actuator configured to actuate a second head over a second disk surface. A seeking control signal is generated and used to control the first actuator to seek the first head over the first disk surface. The seeking control signal is filtered with a decoupler to generate a decoupler control signal, wherein the decoupler comprises a nominal decoupler and an adaptive decoupler. A tracking control signal is generated based on the decoupler control signal, and the tracking control signal is used to control the second actuator in order to access the second disk surface using the second head.

Data storage device employing nominal and adaptive multi-actuator decoupler

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by a plurality of servo sectors. An estimated track ID is generated and a plurality of proximate track IDs is generated having values proximate the estimated track ID. A set of Gray codes is generated each corresponding to the estimated track ID and the proximate track IDs, wherein each Gray code in the set of Gray codes comprises N bits, and M bits out of a high order of the N bits comprise the same value. A recorded Gray code is detected in a first servo sector to generate a detected Gray code, and an error in the detected Gray code is corrected by inverting at least one bit in the detected Gray code comprising a value that is different from the value of the corresponding bit in the M bits.

Disk drive correcting an error in a detected gray code

A disk drive is disclosed comprising a timing loop configured to generate a clock synchronized to a rotation of a disk and a servo loop configured to control an actuator to actuate a head over the disk. A timing signal generated by the timing loop is filtered with a pre-compensation filter (PCF) comprising an inverse transfer function from a delta in a rotation velocity of the disk (&#x394;&#x3c9;) due to a vibration affecting the disk drive to the timing signal, and the actuator is controlled to actuate the head over the disk based on an output of the PCF.

Disk drive using timing loop control signal for vibration compensation in servo loop

A data storage device is disclosed comprising a head actuated over a disk and a vibration detector configured to generate a vibration signal in response to a vibration affecting the data storage device. A timing loop is configured to generate a disk-locked clock substantially synchronized to a rotation frequency of the disk. An adaptation control signal is generated based on the vibration signal and an error signal of the timing loop. An adaptive filter is adapted based on the adaptation control signal, wherein the adaptive filter filters the vibration signal to generate feed-forward compensation values. The feed-forward compensation values are applied to the timing loop to compensate for the vibration.

Data storage device employing adaptive feed-forward control in timing loop to compensate for vibration

A data storage device is disclosed comprising a disk comprising data, and a head actuated over the disk. A timing signal is generated by reading the data from the disk, and a frequency generator is adjusted based on the timing signal to generate a disk locked clock substantially synchronized to a rotation speed of the disk. A free fall condition is detected based on the timing signal, and when the free fall condition is detected the head is parked.

Data storage device detecting free fall condition from disk speed variations

A disk drive is disclosed comprising a servo control system operable to actuate a head over a disk. A sensor signal is filtered with a first filter comprising a frequency response, and the filtered sensor signal is filtered to generate a compensated sensor signal. An error signal is filtered with a second filter comprising the frequency response, and an adaptation control signal is generated based on the compensated sensor signal and the filtered error signal. An adaptive filter is adapted in response to the adaptation control signal, wherein the adaptive filter filters the sensor signal to generate feed-forward compensation values. The feed-forward compensation values are applied to the servo control system to compensate for the disturbance. A disturbance signal that represents the disturbance is generated, and the frequency response of the first and second filters is optimized based on the sensor signal and the disturbance signal.

Disk drive optimizing filters based on sensor signal and disturbance signal for adaptive feed-forward compensation

A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors, a head actuated over the disk, and control circuitry comprising a servo control system operable to servo the head over the disk. A plurality of data tracks are defined relative to the servo tracks, and a first data track is accessed while servoing the head over the first data track based on a position error signal X(k) generated at each servo sector of the first data track. Feed-forward compensation values are generated based on X(k), and a second, consecutive data track is accessed while servoing the head over the second data track based on a position error signal X(k) generated at each servo sector of the second data track and based on the feed-forward compensation values.

Disk drive applying feed-forward compensation when writing consecutive data tracks

A disk drive is disclosed comprising a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors. A position of the head is measured based on the servo sectors, and a compensated position of the head is generated based on the measured position of the head and a fly height of the head. The head is actuated over the disk based on the compensated position of the head.

Disk drive compensating for non-linearity of a head based on a fly height of the head

A disk drive is disclosed comprising a disk, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk. A plurality of disturbance signals is generated in response to a vibration. A plurality of correlations is generated in response to each disturbance signal and an error signal of the servo control system. At least one of the disturbance signals is selected in response to the correlations. A feed-forward compensation value is generated in response to the selected disturbance signal, and the feed-forward compensation value is applied to the servo control system to compensate for the vibration.

Disk drive selecting disturbance signal for feed-forward compensation

A disk drive is disclosed comprising a servo control system operable to actuate a head over a disk. A disturbance signal is generated in response to a vibration, and the disturbance signal is filtered with a first filter comprising a frequency response to generate a filtered disturbance signal. The filtered disturbance signal is filtered with a model of the servo control system to generate a compensated disturbance signal. An error signal of the servo control system is filtered with a second filter comprising the frequency response to generate a filtered error signal. An adaptation control signal is generated in response to the compensated disturbance signal and the filtered error signal, and an adaptive filter is adapted in response to the adaptation control signal, wherein the adaptive filter filters the disturbance signal to generate feed-forward compensation values applied to the servo control system to compensate for the vibration.

Disk drive filtering disturbance signal and error signal for adaptive feed-forward compensation

A disk drive is disclosed comprising a head actuated over a disk having a plurality of data tracks. A vibration is detected, and a write operation is configured to write a first plurality of blocks and a second plurality of blocks to a target data track based on the detected vibration. The first plurality of blocks are written to the target data track during a first revolution of the disk, and the second plurality of blocks are written to the target data track during a second revolution of the disk.

Growing community of inventors

Foothill Ranch, CA, United States of America

Jianguo Zhou