Seagate Technology Incorporated

Reed David Hanson

Timothy Francis Ellis

Nathaniel Boyd Wilson

John Christopher Morris

Kenneth A Haapala

Thomas C Zirps

Brian Robert Pollock

XingHui Huang

Dwight Russell Kinney

Brent Jay Harmer

Mark Larry Birtzer

David L Schell

Alexei Hiram Sacks

Neal Frank Gunderson

Andrew Robert Motzko

Hai Thanh Ho

Jason Dale Gregg

James H McGlennen

Antanas Daugela

Dustin Mark Cvancara

Samir Mittal

Christopher Thomas Settje

Brian W Sudman

Jianbo He

Peng Yan

Steven Alan Koldewyn

Erik Jon Lindquist

Khalil B Dizaji

Ricardo P Freeman

Systems and methods for compensating for hysteresis in a disc drive are described. In one embodiment, a method may use an inverse hysteresis model to linearize effects of hysteresis of a microactuator in the disc drive. The hysteresis model may be a Coleman-Hodgdon hysteresis model. The hysteresis of the microactuator may be characterized, and the inverse hysteresis model may be based at least in part on the characterization. The inverse hysteresis model may be used to implement a digital filter. The digital filter may be employed in series with the microactuator to linearize the effects of hysteresis.

Hysteresis compensation in a disc drive

An apparatus includes an actuator assembly, a dampening assembly coupled to the actuator assembly, and a vibration sensor assembly coupled to the dampening assembly and coupled to the actuator assembly by way of the dampening assembly. A method includes attaching a dampening assembly to an actuator assembly and attaching a vibration sensor assembly to the dampening assembly. The dampening assembly is positioned between the vibration sensor assembly and the actuator assembly.

Methods and devices for detecting shock events

A method is disclosed for positioning a transducer over a magnetic recording medium having a plurality of tracks. The method includes positioning the transducer over a first track using a voice coil motor (VCM) and a microactuator. The method further includes applying a feedforward voltage profile to the microactuator to position the transducer over a second track.

Methods and devices for track seeking using microactuators

Various embodiments of the present invention are generally directed to using a transducer to transfer data during a transducer displacement operation at a time during such operation when the transducer is substantially stationary.

Anticipatory track switching

Compensation for repeated runout (RRO) error, such as in a data storage device servo circuit, is preferably carried out by obtaining a population distribution of RRO error values from at least selected ones of a subset of tracks. An RRO error compensation value is determined for each one of the subset of tracks when a variance characteristic of said population distribution meets a selected criterion. Preferably, a first track of a storage medium has a servo field at a first angular position on the medium, a repeated runout (RRO) error compensation field at a second angular position on the medium, and a user data field at a third angular position on the medium. An immediately adjacent second track preferably has a servo field at the first angular position and a user data field at the second angular position in lieu of an RRO error compensation field.

Zone based repeated runout error compensation

A processor is configured to perform a method () including a step of deriving lateral offset indicators () from a longitudinal position measurement (). Improved seek cost indicators () are generated, some or all based on a respective lateral offset indicator (). Then a target destination is selected using at least one of the improved seek cost indicators ().

Selecting a target destination using seek cost indicators based on longitudinal position

An apparatus and method for compensation for variation in timing skew in a disc drive having at least one rotating disc is provided. A first head is positioned over a first disc surface and a second head is positioned over a second disc surface. The first disc surface includes a track having a first plurality of sectors and the second disc surface includes a track having a second plurality of sectors. Each sector of the second plurality of the sectors corresponds to a different sector of the first plurality of sectors, thereby forming a plurality of pairs of corresponding sectors. A timing skew value for each pair of corresponding sectors is computed to obtain a sequence of timing skew values. Data related to the sequence of timing skew values is utilized to compensate for variation in timing skew.

Compensation for variation in timing skew in a disc drive data storage system

Method and apparatus for certifying servo sectors on recording surfaces of a disc stack of a data storage device to promote servo sector alignment among the various recording surfaces. A reference servo sector pattern is written to a first recording surface, the reference pattern comprising a plurality of angularly spaced apart servo sectors. Multiple interleaved sets of servo sector patterns are written to each of the remaining recording surfaces, each interleaved pattern respectively comprising a plurality of angularly spaced apart servo sectors. A selected interleaved pattern is identified from each of the remaining surfaces that provides a desired alignment with the reference servo sector pattern, and the non-selected servo sector patterns are overwritten. The servo patterns can be written to the discs prior to installation using a multiple disc writing (MDW) station, or after installation of the discs into the data storage device using a servo track writing (STW) station.

Writing multiple servo sector patterns to improve servo sector alignment on multiple surfaces

A data storage system and a method for storing data in a data storage system are provided. The data storage system includes a data storage medium that has at least one physical track that stores at least a portion of manufacturing process data, and virtual tracks that store user data.

Utilizing a combination of physical tracks and virtual tracks to store data on a data storage medium

The present invention recognizes that induced RRO is coherent, i.e., the RRO has a large degree of repeatability from track to track. The present invention is a zero acceleration profile (compensation) process that targets CRRO (Coherent RRO). A process of the present invention represents a considerable reduction in the factory calibration time compared to other compensation techniques currently used. The reduction in time is attributed to the fact that CRRO can be computed by averaging position error signals (PES) over multiple tracks as opposed to total RRO which is computed by averaging over multiple revolutions on the same track.

Written-in error compensation method for coherent repeatable runout

An apparatus and method for tracking radially-dependent repeatable run-out in a disc drive having a servo loop for positioning a head over a rotating disc is provided. The disc includes multiple tracks. Radially-dependent repeatable run-out control components for at least a subset of the multiple tracks are first determined. Data representative of the radially-dependent repeatable run-out control components for the subset of the multiple tracks is then stored. The stored data representative of the radially-dependent repeatable run-out control components is retrieved before settling on the target track, and subsequently used to follow the selected track.

Method and apparatus for tracking radially-dependent repeatable run-out

Using a 'reference' sensor, a reference position is detected in a frame of reference that is moving along a predetermined path relative to the reference sensor. The reference position is used to derive a position-dependent indicator of a position-dependent 'longitudinal' offset component (i.e. along the path). An output from the target sensor is monitored using a &#x201c;target window&#x201d; that is partially based on the position-dependent indicator.

Monitoring a sensor's output using a target window that is based on a longitudinal offset's position-dependent indicator

An apparatus and method of tracking repeatable runout in a disc drive servo loop is provided in which a feedforward signal having harmonic components that are updated at a sample rate that is a fraction of a servo sector sample rate is employed during track following.

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Chaska, MN, United States of America

Reed David Hanson