A disk drive is disclosed which calibrates at least one zone parameter in the field. During an off-line state of the disk drive, at least one of the adapted zone parameters is calibrated. During an active state of the disk drive, a read error is detected and a data-recovery firmware procedure is executed using adapted zone parameters in an attempt to recover data associated with the read error. If the data is successfully recovered from the data sector using the data-recovery firmware procedure, an adapted zone parameter counter is incremented and the operating zone parameters are updated with the adapted zone parameters if the adapted zone parameter counter exceeds a predetermined threshold.

Disk drive for updating operating zone parameters with adapted zone parameters calibrated in the field

Embedded servo sectors within a data track of a hard disk drive including a rotating data storage disk and a closed loop rotary actuator structure for positioning a data transducer head relative to the data track are written by a method including the steps of positioning the rotary actuator structure relative to the data track with a laser-interferometer-based servo writer and writing a pattern of circumferentially sequential, radially offset fine position bursts within each servo sector with the data transducer head, this step including writing-in undetermined position errors within each pattern being written, moving the disk drive to a self scan environment away from the servo writer, operating the rotary actuator structure in closed loop for following the data track by reference to the servo burst pattern, extracting the undetermined position error from each pattern thereby to iteratively determine written-in position errors, generating burst correction values from the determined written-in position errors, and writing the burst correction values to the data track for later use by the closed loop rotary actuator structure during following of the data track to remove the written-in position errors.

In drive correction of servo pattern errors

A system for locating objects in space, such as medical instruments (16) within the body of a patient (P), based upon transmission of magnetic fields from coils (10) in a fixed frame of reference to sensors (20, 22, 24) on the object or vice-versa. The current supplied to the coils is adjusted to assure that the sensors receive fields within a preselected range of magnitudes regardless of the location of the object in space. This assures that the sensor operates within its optimum range, and permits use of compact transmitters and sensors.

Magnetic location system with adaptive feedback control

Disclosed is a control system for processing sampled servo data in a disk drive. The control system includes a microprocessor and a servo processing accelerator circuit for performing operations on the sampled servo data while the microprocessor is executing firmware code. The accelerator circuit supports the use of a higher servo bandwidth thus allowing a higher track density resulting a greater storage capacity for the disk drive. Also, the accelerator circuit relieves the microprocessor of the ordinary servo processing function. Thus, the microprocessor's limited processing capacity to be directed to other controller and interface functions of the disk drive. Only under unusual conditions, such as a write-unsafe (WUS) limit exception, does the microprocessor need to direct processing capacity to the servo processing function. Further, the accelerator circuit may be a decreased response time after reading the servo data from the disk.

Disk drive control system having a servo processing accelerator circuit

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 servo control system provides adaptive compensation for a variety of tracking and seek problems found in disk drives. The servo control system is ideally implemented in digital form for accuracy, speed and compactness. A first embodiment includes two modes, a tracking (or position) mode and a seek (or velocity) mode, each mode employing a variety of compensation functions. A second embodiment includes a single comprehensive control system which functions during both tracking and seek operations.

Digital servo control system for use in disk drives

In a servo controller for controlling the position of a read/write head of a disk drive, a calibrated controller is dedicated to fixed-distance seeks, especially for "single-track seeks" (seeks to an immediately-adjacent track). The controller is first calibrated during a calibration period that precedes an operational period. The purpose of the calibration period is to determine an optimum combination of "calibrated values" for the fixed-distance seeks. "Calibrated values" may include: acceleration pulse magnitude, acceleration pulse duration, deceleration pulse magnitude, and deceleration pulse duration. During the calibration period, various combinations of possible calibrated values are tested during a series of test seeks of the predetermined fixed distance. During each test seek conducted in the calibration period, a cost function is calculated, and the combination of possible calibrated values with the best cost function is chosen for use as the optimum combination of calibrated values during the subsequent operational period. If, during the operational period, the cost function exceeds the cost function of the optimum combination of calibrated values by a predetermined amount, the controller is re-calibrated to maintain optimum performance of the disk drive during fixed-distance seeks.

Digital servo control system for use in disk drives, including calibrated controller for fixed-distance seeks

Digitale servosteuerung für ein plattenlaufwerk

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Digital servo control system for use in disk drives

Digital servo control system for use in disk drives, including calibrated controller for fixed-distance seeks

Digitale servosteuerung für ein plattenlaufwerk