Seagate Technology Incorporated

Maxtor Corporation

Western Automation Laboratories, Inc.

Hai Thanh Ho

Toan Q Doan

Nathan Christopher Thompson

Gregory S Rinard

Eric A Rinard

Brian A Ruff

Bennett C Hinnen

Hossein Zia-Shakeri

Bruce A Liikanen

Justin Won

Jianbo He

Gregory Andrew Campbell

Reed David Hanson

Brent Jay Harmer

Margot Ann LaPanse

Mirmehdi L Abrishamchian

Khalil B Dizaji

Fadi Youssef Abou-Jaoude

Tony Chun-Hung Huang

Charles Leon McHenry

An apparatus and method for compensating actuator arm oscillation induced by resonance mode excitation during a seek in a disc drive data handling system. The actuator arm supports a head adjacent a recording surface, and a servo loop controls the position of the actuator arm. A frequency of actuator arm oscillation is identified, after which a seek is initiated to move the head from an initial track to a destination track on the recording surface. A position error signal (PES) is generated to indicate position of the head relative to the destination track, and a compensation signal is generated by a filter based on the PES and the frequency of oscillation of the actuator arm. The compensation signal is adapted to remove a component of the PES arising from the actuator arm oscillation, and is applied to the servo loop as the head is settled onto the destination track.

Reducing actuator arm oscillation during settle mode in a disc drive servo system

A digital sine/cosine wave generator generates discrete values representative of either a sine wave or a cosine wave. The digital sine/cosine wave generator generates sine and/or cosine waves by implementing a difference equation of the form y(n)=b*y(n&#x2212;2)&#x2212;y(n&#x2212;1). One of the initial conditions of the difference equation is selected from a series of values generated by a coefficient generator. The frequency of the sine and/or cosine wave generated by the sine/cosine wave generator is dependent on, and may be selected according to, which of the series of values generated by a coefficient generator is chosen as an initial condition of the difference equation.

Digital sine/cosine wave generator

Method and apparatus for more accurate track following. Control circuitry rotates a data storage surface containing thousands of annular tracks. A 'measured' subset of the tracks is selected so as to be interspersed with an 'unmeasured' subset. The calibration profile is derived based on position error signals each obtained by reading from the measured subset and not from the unmeasured subset. Data from the unmeasured subset of tracks is ignored, in generating and/or updating the profile.

Efficient feedforward compensation for repeatable runout in a disc drive

An apparatus and method for compensating repeated runout position error in a disc drive data handling system having an actuator assembly which supports a head adjacent a recording surface. A servo loop generates a position error signal (PES) to control the position of the head. A digital filter is configured to place a notch in an error sensitivity function relating the PES to the repeated runout position error, with the notch being nominally centered at a frequency of rotation of the recording surface. The filter thereafter filters the PES to generate compensation signals that are injected into the servo loop. At least selected filter parameters are determined by measuring the frequency response of the servo loop and used as a priori knowledge to produce a loop matching effect that results in a consistent convergence rate for any targeted frequency to be filtered.

Repeated runout position error compensation in a disc drive servo system

A disc drive actuator system includes an equalizer filter coupled between the controller and actuator plant of a disc drive actuator system. The filter applies a gain of less than unity gain to the actuator drive signals from the controller at the resonance frequency of the plant, and applies a gain greater than unity to the actuator drive signals at a selected frequency different from the plant resonance frequency to derive a system resonance frequency shifted from the plant resonance frequency. In one form the equalizer filter functions as a notch filter to attenuate signals at the plant resonance frequency, and functions as a peak filter to boost the gain of higher frequency signals over a band wide enough to ensure zero phase loss below the plant resonance frequency.

Method and apparatus for electronically shifting mechanical resonance of an actuator system of a disc drive

A method and system for identifying the resonance characteristics of a disc drive. A repetitive excitation signal is applied to the actuator assembly. The repetitive excitation signal has a period substantially equal to a positive integer multiple of a period of revolution of the disc. The position of the read/write head relative to a target track on the disc surface is sensed. The sensed position of the read/write head is compared to a desired position of the read/write head and apposition error signal indicative of the difference between the sensed position and the desired position is generated. The position error signal is time averaged over multiple revolutions of the disc to obtain an averaged repetitive position error signal. The resonance characteristics of the drive is determined based on a correlation of the averaged repetitive position error signal with respect to the repetitive excitation signal.

Disc drive dynamics identification using synchronous excitation signal

An apparatus and method for canceling nonrepeatable runout position error in a disc drive. Pursuant to the method, a frequency of a specified nonrepeatable runout disturbance is determined. A position error signal indicative of a position of a read/write head relative to a track is received. A signal is generated based upon the frequency of the specified nonrepeatable runout disturbance and the received position error signal. The generated signal is applied to the servo loop. Applying the generated signal to the servo loop cancels a component of the position error signal arising from the specified nonrepeatable runout disturbance. In an illustrative embodiment, applying the generated signal to the servo loop produces a notch in an error sensitivity function relating the position error signal to a general nonrepeatable runout disturbance, the notch being centered at the frequency of the specified nonrepeatable runout disturbance.

Disc drive resonance disturbance cancellation filter

A method and apparatus are provided for generating a feedforward cancellation signal for a next sector of a disc in a disc drive. To form the cancellation signal, the method and apparatus generate a trigonometric value having the phase and frequency of a nonrepeatable runout error by passing a position error signal through a phase lock loop. An amplitude is determined for the cancellation signal based on the position error signal. The amplitude is then multiplied by the trigonometric value to from the cancellation signal.

Method and apparatus for feedforward cancellation using a phase lock loop

A method and apparatus are provided for generating a feedforward cancellation signal for a next sector of a disc in a disc drive. To form the cancellation signal, the method and apparatus estimate the phase and frequency of a nonrepeatable runout error in a position error signal. A peak detector is then used to identify a peak amplitude of the nonrepeatable runout error for a current sector. Using the peak amplitude, an amplitude is determined for the cancellation signal for the next sector. A time-varying signal is then evaluated based on the estimated phase and frequency and the result of the evaluation is multiplied by the amplitude to produce the cancellation signal.

Method and apparatus for feedforward cancellation using a peak detector

A system for positioning a read/write head having a voice coil suitable for coarse control and a piezoelectric transducer (PZT) suitable for fine control. A voice coil control signal and a PZT control signal are generated from a position-indicative signal, both receiving power via a shared supply having a nominal rectified voltage V In a preferred method, control signals are both applied to the voice coil and PZT when amplified so that each has a saturation voltage smaller than &verbar;V

Dual stage positioning system using a shared voltage source

The invention relates to a disk drive servo apparatus, and method for implementing the same, that maintains a transducer on a substantially non-perturbed path despite the fact that the tracks were written in a perturbed manner by a servo track writer. The invention utilizes a non-causal filter to determine servo track writer repetitive run-out (STW_RRO) values for each sector of each track at the drive level. The STW_RRO values are stored, preferably in their respective servo sectors on the surface of the disk, for use during track following operations. During read and write operations, the STW_RRO values are retrieved from storage and are used to generate position error signals necessary to maintain the transducer on the desired path.

Disk drive with compensation values calculated using a non-causal impulse response

The invention relates to a disk drive servo apparatus, and method for implementing the same, that maintains a transducer on a substantially non-perturbed path despite the fact that the tracks were written in a perturbed manner by a servo track writer. The invention utilizes a non-causal filter to determine servo track writer repetitive run-out (STW.sub.-- RRO) values for each sector of each track at the drive level. The STW.sub.-- RRO values are stored, preferably in their respective servo sectors on the surface of the disk, for use during track following operations. During read and write operations, the STW.sub.-- RRO values are retrieved from storage and are used to generate position error signals necessary to maintain the transducer on the desired path.

Efficient drive-level estimation of written-in servo position error

A servo sector allocation scheme for a disk based data storage system is disclosed that realizes an increased servo sampling rate without an associated increase in overhead. The scheme involves increasing the number of servo sectors on a subset (preferable one) of the disk surfaces in the disk drive while reducing the number on all remaining disk surfaces. A master servo feedback signal is then derived from the highly populated surface(s) and a slave servo feedback signal is derived from the surface that is being accessed. The master and slave servo feedback signals are then combined to form a single position error signal that is used to control the positioning of an appropriate transducer.

Disk drive with multiple disk surfaces having improved allocation of

Servo sector allocation for high sampling rate

A storage system (10) is disclosed that provides random access storage/retrieval of data on data cartridges within the storage system (10). In one embodiment, the storage system (10) includes a storage array (20), a player/recorder device (22), and a cartridge transport device (40). The player/recorder device (22), a guard device (80) and the transport device (40) are positioned on substantially opposite sides of the storage array. The transport device (40) moves cartridges between the storage array (20) and the player/recorder device (22). The guard device (80) pushes a prolapsed data cartridge back into the storage array (20) and/or limits the distance a data cartridge will prolapse from the storage array (20).

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Westminster, CO, United States of America

Hai Thanh Ho