Abstract: A disk drive is disclosed comprising a disk having a plurality of tracks, and a head actuated over the disk. The disk drive further comprises control circuitry including a fly height actuator. A fly height map is measured for at least one track. A constant FHC signal applied to the fly height actuator is adjusted to decrease an average fly height of the head. After decreasing the average fly height of the head, a fluctuating fly height control (FHC) signal is applied to the fly height actuator to adjust a fly height of the head in response to the fly height map. When the head contacts the disk, an operating FHC signal is determined. The operating FHC signal is applied to the fly height actuator while executing at least one of a read and write operation.

Abstract: In one embodiment a tape drive system comprises a reel adapted to engage a tape cartridge, the tape cartridge comprising a tape media having a servo code written along a length of the tape media, a tape head comprising at least one servo element to detect the servo code, a drive assembly to induce relative motion between the tape and the tape drive, a servo system to control the lateral and longitudinal motion between the tape and the tape head, the servo system comprising a sampling module to sample servo data from the tape media, and a position signal processor to calculate a position signal using the servo data from the sampling module, wherein the position signal processor calculates a position signal based on each adjacent servo element set.

Abstract: Various embodiments of the present invention provide systems and methods for determining fly-height adjustments. For example, various embodiments of the present invention provide storage devices that include a storage medium, a read/write head assembly disposed in relation to the storage medium (278), and a SAM based fly-height adjustment circuit (214). The storage medium (278) includes a plurality of servo data regions (110) that each include a servo address mark (154). The SAM based fly-height adjustment circuit (214) receives the servo address mark (154) from the plurality of servo data regions (110) via the read/write head assembly (276), and calculates a first harmonics ratio (445) based on the received data. The first harmonics ratio (445) is compared with a second harmonics ratio (450) to determine an error (365) in the distance (295) between the read/write head assembly (276) and the storage medium (278).

Abstract: In one embodiment a tape drive system comprises a reel adapted to engage a tape cartridge, the tape cartridge comprising a tape media having a servo code written along a length of the tape media, a tape head comprising at least one servo element to detect the servo code, a drive assembly to induce relative motion between the tape and the tape drive, a servo system to control the lateral and longitudinal motion between the tape and the tape head, the servo system comprising a sampling circuit assembly to sample servo data from the tape media, wherein the sampling circuit assembly samples both positive readback waveforms and negative readback waveforms generated by servo code on the tape, a pulse time demodulator circuit module to generate timestamped, digital signals from signals generated by the sampling circuit assembly, and a position signal processor to calculate a position signal using the servo data from the pulse time demodulator circuit module.

Abstract: According to one embodiment, a position control apparatus includes: a digital control module that performs position control including disturbance adaptive control with a predetermined sampling period using a control constant, in accordance with a position error between a target position and a current position of the object; and a table that stores the control constant corresponding to a value of sin(?T) or cos(?T), wherein the digital control module is configured to determine a control value of the actuator in accordance with the position error, calculates the value of sin(?T) or cos(?T) according to an adaptive law from a signal based on the position error, reads the corresponding control constant from the table in accordance with the calculated value of sin(?T) or cos(?T), and updates the control constant, to perform the position control including the disturbance adaptive control.

Abstract: An HDD parking ramp is disclosed and includes a guide portion having an inclined surface adapted to receive a lift tab associated with an actuator mounting a read/write head during an unloading/parking operation, and a parking surface adapted to accommodate the lift tab at the completion of the unloading/parking operation, an installation support portion fixed in the HDD and adapted to support the guide portion, and a vertically adjustable driving device provided between the guide portion and the installation support portion and adapted to position the guide portion at a first vertical height relative to the installation support and a second vertical height greater than the first vertical height.

Abstract: Methods, servo systems, and data storage drives follow the lateral shift excursions of longitudinal tape, for example, from flangeless tape guides. A servo sensor is configured to sense lateral position of a tape head with respect to longitudinal servo tracks of the tape, a fine actuator is configured to translate the head laterally, and a coarse actuator is configured to translate the fine actuator laterally. Position error is determined between the head and a desired position related to the servo track, and the fine actuator operated to translate the head laterally to reduce the position error. In the embodiment, lateral shift excursion is sensed from the position error, and the coarse actuator is positioned substantially at a midpoint of the lateral shift excursion. Thus, the fine actuator follows the lateral shift excursions, while the coarse actuator remains at the midpoint.

Abstract: According to one embodiment, an information storage device includes a recording/reproducing head, a positioning controller, a position detector, a storage module, and a position error detector. The position detector detects the position of the recording/reproducing head. The storage module stores servo control filters. The position error detector generates a new position error signal from a target position and the position of the recording/reproducing head when the positioning controller performs positioning control with control current obtained from a position error signal having passed through each servo control filter. Upon occurrence of a recording/reproducing error, learning to calculate a vibration amount from the position of the recording/reproducing head is sequentially performed for the servo control filters for a predetermined time.

Abstract: According to one embodiment, in a disk drive, a voice coil motor is controlled to cause a head to minutely vibrate in a radial direction on a track of a disk. When the voice coil motor vibrates the head in the radial direction of the disk, frictional force occurring between the disk and the head is calculated based on the driving force of the voice coil motor generated to vibrate and detected positional information, thereby measuring frictional characteristics.

Abstract: Various embodiments of the present invention provide systems and methods for using channel bit density estimates to adjust fly-height. For example, various embodiments of the present invention provide methods for adaptively adjusting fly-height. Such methods include providing a storage medium that includes information corresponding to a process data set, and a read/write head assembly that is disposed a variable distance from the storage medium. The process data set is accessed from the storage medium. A first channel bit density estimate is adaptively calculated based at least in part on the process data set and a second channel bit density estimate that was previously calculated. The variable distance is modified based at least in part on the first channel bit density estimate. A third channel bit density is adaptively calculated based at least in part on the process data set and a fourth channel bit density estimate that was previously calculated.

Abstract: A method for manufacturing a hard-disk drive (HDD). The method for manufacturing a HDD includes writing servo tracks, and writing servo tracks into the HDD using a calculated control target value of a calculated servo pattern overlap amount. Writing servo tracks includes a first, second, third and fourth operation. The first operation includes: producing a first control equation for obtaining a servo pattern overlap amount; and, converting a root-mean-square error (RMSE) into a probability distribution. The second operation includes calculating a second control target value that results in an increased product yield, from the RMSE probability distribution. The third operation includes producing a second control equation for obtaining a calculated servo pattern overlap amount, by assigning the second control target value into the first control equation.

Abstract: A method, apparatus and program storage device for dynamically adjusting the write current in each head to compensate for variation in disk drive and environmental parameters is disclosed. A current in the write head is dynamically adjusted to compensate for variations in the components and environment by periodically measuring the writability of the drive and adjusting the write current such that the parameter stays within predetermined criteria.

Abstract: A servo track writing method and a servo track write system of a hard disk drive (HDD) using the servo track write method. The servo track writing method includes performing a reference check (R/C) on a first servo pattern which is pre-written on a first surface of a disk, and if the R/C determines that a quality of the first servo pattern is not good, erasing a specific area of the first servo pattern and writing a second servo pattern on a second surface of the disk. Therefore, process time delay factors of a series of rework processes of writing servo patterns on a disk are removed to shorten a process time of the rework processes. In addition, productivity of a HDD is improved.

Abstract: A disk drive for determining a write jog value is disclosed. The disk drive comprises: a disk; a head including a reader and a writer; and a processor. The processor controls operations in the disk drive including: commanding the reader to track follow on a first track, wherein the writer is located over an uncalibrated track position; commanding the writer to write a first test pattern on a section of the disk; commanding the writer to move by a plurality of step amounts to write a plurality of test patterns; commanding the reader to move by a second plurality of step amounts to read the plurality of test patterns; determining a reader signal value associated with each test pattern; determining the uncalibrated track position based on the read signal values; and determining the write jog value based on the distance between the first track and the uncalibrated track position.

Abstract: Methods, systems, and apparatus, including computer program products, are described for calibrating voice coil motors. In one aspect, a method is provided that includes seeking toward an outer diameter of a machine readable medium from a target servo track to a blank portion of the machine readable medium. A radial velocity of an actuator is determined after accelerating the actuator to a target radial velocity. The radial velocity is compared to the target radial velocity, and a current, that is used to controllably modify the radial velocity of the actuator if the radial velocity is different from the target radial velocity, is calibrated.

Abstract: A fly height control system includes a weighting function module. The weighting function module applies coefficients from a window function in a time domain to digital samples to provide weighted samples. A first of the coefficients is applied to a first of the digital samples and a second of the coefficients is applied to a second of the digital samples. The first of the coefficients has a first magnitude that is different than a second magnitude of the second of the coefficients. The system also includes a harmonic sensor module that estimates a magnitude of a frequency in a frequency domain based on the weighted samples. The system also includes a head height control module that determines a height of a read/write head over a storage medium based on the magnitude of the frequency.

Abstract: A speed control system for a rotating storage device including a mode selection module configured to select an operating mode or a standby mode to operate the rotating storage device based on use of the rotating storage device and to select the standby mode after a first predetermined period during which reading and writing to the rotating storage device is not performed. The first predetermined period is selected based on a type of device in which the rotating storage device is implemented. The speed control system includes a speed control module configured to select a predetermined operating speed to rotate a storage medium of the rotating storage device when the operating mode is selected and to select a predetermined standby speed to rotate the storage medium when the standby mode is selected. The predetermined standby speed is (i) less than the predetermined operating speed and (ii) greater than zero.

Abstract: A servo writer is disclosed for writing servo data onto a disk of a disk drive. The servo writer comprises a push-pin operable to contact an actuator arm of the disk drive, an actuator for actuating the push pin, and a retract capacitor. The retract capacitor is charged, and the actuator actuates the push-pin in order to position the head radially over the disk. If a power failure occurs while actuating the push-pin, a current is applied from the retract capacitor to a voice coil of the actuator arm in order to retract the actuator arm.

Abstract: According to one embodiment, a system includes a plurality of synchronous servo channels with each synchronous servo channel including a servo reader included in a magnetic head, and logic for applying a plurality of first control signals to a skew-following loop. Each first control signal includes a reference shift value, each reference shift value corresponds to one of a number of hypotheses, and each hypothesis corresponds to one servo band set. The system also includes logic for computing an average difference between lateral position estimates from the plurality of synchronous servo channels, logic for selecting a hypothesis from the number of hypotheses that corresponds to a maximum of the computed average difference, and logic for applying a second control signal to the skew-following loop. The second control signal includes a reference shift value that corresponds to the selected hypothesis. Other systems and methods are also described.

Abstract: There is provided a method for generating acceleration data used in feed-forward control of head seeking, wherein, a seek distance and one of a seek period and the count of samples are received; a weighting factor for the change rate of acceleration between adjacent sample times is determined respectively; and an optimum acceleration at each sample time is obtained by performing an optimization calculation that minimizes an objective function under a constraint condition based on variables representing accelerations at each sample time, either the seek period or the count of samples, and the seek distance.