Abstract: 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.

Abstract: A method and apparatus for an error-correction buffer having self-throttling data burst control in a disc drive. One aspect of the present invention provides an arbitration-throttling control circuit for use in a disc drive to self-throttle the data transfer of an error-correction buffer. The arbitration-throttling control circuit includes a control circuit having an error-correction buffer interface and a disc-drive main buffer memory interface for controlling data transfer from the error-correction buffer to a disc-drive main buffer in a plurality of data bursts. The control circuit arbitrates for access to transfer data into the disc-drive main buffer such that a series of data bursts from the error-correction buffer to the disc-drive main buffer are spread substantially evenly over a period of time.

Abstract: Method and apparatus for detecting defects in a magnetic medium of a data handling system. The magnetic medium includes a number of user data wedges each disposed between an adjacent pair of servo data wedges. A predetermined data sequence is written to the user data wedges, and subsequently read to generate a readback signal. A sequence of discrete time sample values are generated from the readback signal. Defects in the medium are detected in relation to the magnitudes of the discrete time samples. A media scan controller outputs a first multi-bit information record having at least one bit composing the address of the user data wedge containing a defect, and a second multi-bit information record having at least one bit composing an address of the defect within the user data wedge. No information is written to the buffer when no defects are identified.

Abstract: 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.

Abstract: Problems inherent in guiding a sensor via a piecewise-linear lateral parametric profile are generally avoided using at least one broadly curved, generally lateral profile (494). A sensor is configured to move in a nominally longitudinal direction relative to a frame of reference (110). A position scale is defined in a generally lateral direction relative to the longitudinal motion (115). Each broadly curved lateral profile is defined in terms of its corresponding position scale, the scale(s) and the profile(s) both being part of a parametric model that is available for use in guiding the sensor (145).

Abstract: By dynamically adjusting the maximum voice coil motor driving current produced by an amplifier in a disc drive, amplifier saturation may be reduced, while still maintaining optimal current to quickly drive the voice coil motor during seek operations. Reducing disc drive saturation, and thus non-linearities in the driving current, increases notch filter performance. As the notch filter is used in the disc drive to remove frequencies from the driving current that tend to cause or excite the mechanical oscillations in the disc drive, increased notch filter performance reduces mechanical oscillations and improves disc drive noise characteristics.

Abstract: A method and apparatus for improving the settle time and thus, the transition from seek control to track following control in a disc drive system are provided. With the apparatus and method, two counters are provided—a consecutive counter and a non-consecutive counter. The consecutive counter counts consecutive samples that meet threshold requirements. The non-consecutive counter counts non-consecutive groups of consecutive samples that meet threshold requirements. When the consecutive counter reaches a first predetermined value, the non-consecutive counter is incremented and the consecutive counter is reset to zero. When the non-consecutive counter reaches a second predetermined value, a track following control mechanism is initiated to thereby transition from a seek control operation to a transitional control operation and finally a track following control operation.

Abstract: A system and method for improving write integrity of a magnetic storage system. A settling algorithm counter is reset if a position error signal of the write head indicates the head is vibrating with mechanical oscillations outside a predetermined threshold.

Abstract: Optimal command nodes are selected in a computing device having multiple command node queues by a method which identifies a command node in a first queue and determines if the identified command node collides with a command node in a second queue. If a collision between the identified command node and a command node in the second queue is determined, the collision is corrected and the identified command node then may be moved into the second queue. The second queue is then sorted according to a predetermined routine to select the optimal command node.

Abstract: Method and apparatus for moving a control object, such as a data transducing head in a data storage device, from an initial position to a destination position. A base generation term describes a normalized trajectory (acceleration, velocity, displacement) of the control object away from the initial position and toward the destination position. A control profile is determined in relation to the base generation term as well as in relation to an acceleration distance and an acceleration time, respectively characterized as a displacement distance and an elapsed time during which the control object is accelerated. The control object is then moved in relation to the control profile. The base generation term is preferably stored in a table which is accessed and scaled in relation to the displacement distance (seek length) for the control object.

Abstract: A method and apparatus for improving the timing of a seek operation through the removal of the coast phase of conventional model reference waveform type control systems are provided. With the apparatus and method, the coast phase is removed such that an acceleration phase is immediately followed by a deceleration phase in the waveform of the control system. A (1-Cos)/2 shaping is applied to the resulting square waveform so that the affects of high frequency harmonics are minimized. The resulting “cosine bang-bang” waveform provides a reduction in seek time when compared to conventional model reference waveform based control. In addition to the above, the present invention provides a controller architecture in which the cosine bang-bang waveform may be applied to a voice coil motor to control the actuation of the read/write heads of a disc drive.

Abstract: 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.

Abstract: A skip mask mechanism is implemented in a disc drive in order to increase performance by minimizing the number of necessary disc rotations required while executing a set of pseudo-sequential commands. The drive includes an interface between the host computer and the drive, a read/write channel between the interface and the transducer/head, a formatter between the interface and the read/write channel for timing when data is transferred between the interface and the read/write channel, and a skip mask mechanism interposed between a target calculator and the formatter that provides a masked input to the formatter for controlling passage of data between the interface and the read/write channel.

Abstract: Position error values are obtained from a transducer head while following a plurality of servo tracks with a servo loop that band-blocks a frequency range that includes F, a nominal rotation frequency. An estimated difference distribution is derived from the position error values, the difference distribution having a first frequency component at a positive frequency ?2*F. A scalar track squeeze magnitude indicator is derived from the estimated difference distribution so that the indicator to be transmitted depends on the frequency component.

Abstract: A number of data pairs, each data pair comprises a write-to-read track misregistration (WRTMR) value and an average position error margin (APE) value, are determined for a data storage device. Each of the data pairs is associated with a unique predetermined non-repeatable runout (NRRO) error in the data storage device. Each of the predetermined NRRO errors is caused by subjecting the data storage device to a unique NRRO error stimulus. An ideal APE margin is then determined for the data storage device by using the data pairs to extrapolate an APE margin corresponding to a WRTMR value of zero.

Abstract: A system and method for correcting repeatable runout errors during manufacture of a disc drive. The system includes a Kalman filter having a recursive learning gain input and includes a recursive learning Again-setting circuit coupled to the recursive learning gain input. The recursive learning gain is initially set based on an estimate of a ratio of non-repeatable run out error to an estimate of the repeatable run out error. On subsequent recursions, the recursive learning gain-setting is reduced.

Abstract: A method for optimizing the read-to-write offset of a disk drive system in respect of a track is provided. In one aspect the method includes the step of determining a first read position amongst a range of test positions offset relative to the track on the basis of read signal strength. The method further includes the steps of calculating a subrange of test positions about the first read position, selecting a second read position from the subrange on the basis of bit error rates and setting the read-to-write offset as a function of the second read position. In addition a disk drive system including means for optimally setting the read-to-write offset in respect of a track is provided.

Abstract: A method of handling resonance effects on disc drives includes the steps of monitoring a position error signal (PES) for an actuator arm of a disc drive, generating a feedforward compensation signal from the PES using a bandpass filter, and applying the compensation signal to a servo control signal. The bandpass filter has a center frequency set to a known resonance frequency. A disc drive includes an actuator assembly including an arm for carrying a head in a transducing relation with respect to a disc in response to a control signal, and a controller that monitors a PES for the arm and generates the control signal. The controller includes a servo controller that generates a servo control signal from the PES, and a feedforward compensation element which bandpass filters the PES to generate a compensation signal which is combined with the servo control signal to generate the control signal.

Abstract: A transducer position sensing system in a disc drive to take frequent data measurements from micro-servo sectors on the disc and to interpret the information to predict recording failures. The disc drive is formatted with many small or micro-servo sectors containing, among other things, a servo address mark, encoded disc location information, and radial track position information. The sensing system frequently retrieves this information through the transducer, compares the measurements to expected values, and given unexpected measurements predicts errors. The time elapsed between the passing of servo address marks can be used to predict adjacent sector overwrites. The radial track position information can be used to predict off-track write errors. The radial track position signal amplitude can be used to predict the transducer moving too far from the disc, resulting in skip write errors.

Abstract: A data storage device control module for controlling operational processes in a data storage device comprises a number of preemptive modules, a number of non-preemptive modules, and a scheduler module operable to schedule the execution of the non-preemptive modules only in the data storage device control module. Preferably included as one of the non-preemptive modules is a queue processor module operable to manage the position and movement of command nodes in multiple command node queues.