Seagate Technology Incorporated

David Charles Waugh

Robert Dale Murphy

Lealon Ray McKenzie

Randall D Hampshire

Matthew Chad Burton

Clyde Everett Goodner, Iii

Ryan Todd Lyle

Jeffrey Don Andress

James W Dulaney

Mark A Hickl

Michael A Rider

Method and apparatus for performing a seek operation to move a data transducing head from an initial track to a destination track on a rotatable recording surface. A servo control circuit operates to sweep the head across the recording surface. Servo data from an intermediary track are transduced to obtain a detected angular position value for the head with respect to the recording surface. When the detected angular position value differs from a predicted angular position value for the head, the servo control circuit initiates an index qualification routine at the conclusion of the seek. The qualification routine involves transducing the servo data from the destination track to verify the accuracy of the predicted angular position value. In this way, the effects of spurious (false) index signals obtained from the servo data transduced during the seek operation are minimized, and unnecessary reinitializations of the servo control circuit are avoided.

Adaptive index reference position qualification

A method and apparatus are disclosed for improving seek performance of a disc drive through adaptive servo gain adjustment. The disc drive comprises a head adjacent a rotatable disc and a servo circuit which controllably positions the head adjacent tracks defined on the disc. During a seek operation in which the servo circuit moves the head from an initial track to a destination track, the servo circuit accumulates a velocity error as a sum of a series of velocity errors each obtained as a difference between an actual velocity of the head and a corresponding desired velocity over a selected radial distance of the disc. The servo circuit additionally measures an elapsed time for the head to pass over a second selected radial distance of the disc as the head is decelerated toward the destination track. Thereafter, the servo circuit adjusts a gain of the servo circuit in relation to the accumulated velocity error and the measured elapsed time.

Adaptive servo gain adjustment to improve disc drive seek performance

Disclosed is a method of compensating for non-optimal operating conditions during a sine seek operation. A disc drive with a seek controller provides a feedforward signal to an actuator during a portion of the operation of an actuator and provides a velocity signal during another portion of operation of the actuator. The controller also stores a velocity error switch point. If it is determined that the feed forward signal is lower or higher than a first nominal value, then the feed forward signal provided by the controller is adjusted. Furthermore, if it was determined that the feed forward signal is lower than the first nominal value, the velocity error switch point is decreased.

Sine seek adaptation at voltage and temperature margins

Apparatus and method for reducing the generation of acoustic noise in a disc drive. A seek is carried out to move a head from an initial track to a destination track on a corresponding disc surface using a servo circuit which outputs a series of current command values indicative of successive magnitudes of current to be applied to an actuator motor. A velocity profile provides a sequence of demand velocities indicative of the desired velocity at each of a succession of time periods during the seek. Closed loop velocity control is achieved by comparing the actual velocity of the head to the corresponding demand velocity and adjusting the current in relation to the velocity error therebetween. During initial stages of the seek, however, open loop control is initially performed using a current profile table which shapes the initial stages of current to a desired waveform, irrespective of the velocity profile and the velocity error.

Reducing acoustic noise using a current profile during initial stages of a disc drive seek

A method for adapting acceleration and deceleration of a disc drive transducer during movements between initial and target tracks on a disc surface to the maximum current available to drive an actuator whereon the transducer is mounted. During acceleration of the transducer, while the actuator current is substantially a maximum, the current supplied to the actuator coil is measured and a scale factor is determined as the square root of the ratio of the maximum current supplied to the actuator and a nominal current from which a velocity profile, used to effect velocity control of the movement, has been predetermined. Thereafter, the current supplied to the actuator is adjusted in a succession of time intervals by measuring the velocity of the transducer, determining a profile velocity in each interval from the velocity profile, generating a demand velocity by scaling the profile velocity by the scale factor, generating a correction signal from the difference of the measured and demand velocities, and supplying current to the actuator in proportion to the correction signal.

Method for adapting seeks of a disc drive transducer to the maximum

A method and apparatus for testing for mechanical defects in a disc drive during manufacturing test is disclosed. The disc drive performs a special test seek to a destination track involving maximum acceleration and deceleration current to induce resonant frequencies in an actuator servo position error (SPE) signal. During track following on the destination track, the SPE is filtered by a sample and accumulate operation, resulting in the detection and characterization of the resonant frequency. The characteristics of the detected and characterized resonant frequency are compared to predetermined maximum acceptable threshold values, and when the characteristics exceed the threshold values an error flag is set, indicating a failure condition for the disc drive, enabling the disc drive to be removed from test for subsequent remedial actions.

Detection of mechanical defects in a disc drive using resonant

A data storage system comprised of a plurality of disc drives which each comprise a plurality of data storage discs rotated by a polyphase motor. Each disc drive has a servo system for radially positioning transducer heads proximate the disc surfaces and generating an index signal for a selected orientation of the discs. A reference signal generator in each disc drive produces a reference signal at each of a succession of time intervals equal to the desired period of rotation of the discs and the disc drives are interconnected to enable each disc drive to sense a reference signal generated by any other disc drive. Each disc drive includes a microcomputer that is periodically interrupted and, during the interrupt, transmits the reference signal generated by the disc drive to the other disc drives in the absence of reception of a reference signal from another disc drive prior to the interrupt to provide a common reference signal for all of the disc drives. The speed of the motor of each disc drive is controlled in relation to the time interval between generation of the index signal in the disc drive and generation of the common reference signal. Alternatively, each disk drive can be operated independently to control the motor speed in relation to the time between successive index signals.

Hard disc drive for use in a multiple drive data storage system and

A method for eliminating overshoot of a destination track by a servo head of a rotating disk data storage device during seeks wherein the seek is carried out in accordance with an adaptive velocity demand profile selected to undershoot the destination track by an amount sufficient to offset overshoot arising from an incapacity of the servo head to follow a velocity demand profile. Prior to performing the seek, the servo head is moved a distance about a null position on the disk at which the only force on the actuator on which the head is mounted arises from a constant current passed through the actuator and the time for the movement is measured and utilized to select the adaptive demand profile. Adaptive demand profiles are obtained by performing seeks while modifying a nominal profile to eliminate actuator current ringing at the end of the seek.

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Oklahoma City, OK, United States of America

David Charles Waugh