Abstract: Many parallel tracks on a storage surface of a data handling device are arranged in a longitudinal direction. Each track has a track center comprising reference points for fine lateral positioning. Each successive pair of track centers has a succession of lateral offset distance having an average. Because there are many successive pairs of tracks, there are many average lateral offset distances defining a statistical distribution having a variance. The device includes a laterally movable transducer head and a longitudinally movable data surface. A signal is received from the transducer head while the data surface moves past the head. Many values each indicative of a lateral offset distance between a corresponding pair of lateral reference points are derived from the received signal. These offset-indicative values are used to shift at least some of the latitudinal reference points laterally so as to reduce this variance.

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: Linearizing hysteresis of a microactuator for a disc drive by modeling the microactuator with a first polynomial equation to provide a linear displacement response of the microactuator responding to an applied voltage, deriving a set of constants from a plurality of burst patterns for use with the first polynomial equation to provide a set of variables for use in resolving the second polynomial equation to provide a set of equations from which a set of constants can be derived for use by the second polynomial equation to provide a voltage to the microactuator to displace the microactuator by a predetermined incremental distance.

Abstract: Disclosed are methods and systems for more accurately measuring the performance of a data-storage device by compensating for the repeatable runout (RRO) errors that are written-in to tracks during manufacture. During the manufacturing process, the disc is divided into zones containing a number of tracks. A representative RRO, known as the coherent RRO (CRRO), in each zone is obtained by sampling the position error signal (PES) of some or all of the tracks in each zone and, in one embodiment, using the average PES for the zone as the CRRO. The CRRO, which is the majority of the PES, is removed from the PES to create a corrected error signal (CES). The CES is used to evaluate the performance of the data-storage device rather than the PES. Because the CRRO does not affect the performance of the data-storage device, removing it results in a more accurate measurement.

Abstract: Steps for isolating and correcting total written-in repeatable run-out error written into servo sectors of a disc drive include, determining a total repeatable run-out error value for each servo sector, isolating a repeatable error value component of the total written-in repeatable run-out error value for each servo sector, removing the repeatable error value component from total written-in repeatable run-out error value to provide a non-repeatable error value component of the total written-in repeatable run-out error value for each servo sector, providing both the repeatable and non-repeatable error value components to a processor for generation of compensation signals, and applying the compensation signals into a servo control circuit of control loop of the disc drive using compensation circuits to compensate for each component of the total written-in repeatable run-out error.

Abstract: A method of preventing a write operation to a disc in a disc drive during a shock event without the use of a separate shock sensor comprises steps of monitoring an actuator voice coil motor (VCM) control plant output signal, generating an actuator voice coil motor (VCM) plant model module output signal, comparing the VCM plant model module output signal to the VCM control plant module output signal to produce a difference signal, and triggering a write protect gate if the difference signal exceeds a predetermined threshold value.

Abstract: A disc storage system is provided which includes a servo control loop for compensating for repeatable runout. Repeatable runout is compensated using table entries of the form Comp Value(k+1)=Comp Value(k)+K&PHgr;(z)RRO(k), where K is a learning rate; k is iteration number &PHgr;(z) is a filter and RRO(k) is the repeatable runout error. Further, &rgr;(j&ohgr;)=|1−K&PHgr;(j&ohgr;)/(1+PC(j&ohgr;)|<1 needs to be satisfied, where PC(j&ohgr;) is an open loop frequency response of the servo loop. The filter can comprise a order filter.

Abstract: A method of, apparatus for, and means for controlling pitch of a servowritten track on a disc in a disc drive are disclosed. The disc drive has a head for traversing over a surface of the disc. The head has a read element and a write element separated by a head element offset &Dgr;. A servowriting controller operably connected to the disc drive creates a track k by writing servo information on the disc. The servowriting controller then calculates the head element offset &Dgr; at the track k, [&Dgr;CALC(k)] and determines a skew angle &thgr; at the track k, [&thgr;(k)]. The servowriting controller adjusts a track pitch correction factor based on the &Dgr;CALC(K) and the &thgr;(k) such that the track pitch correction factor is utilized to servowrite a next track.

Abstract: A method and apparatus are provided for positioning a head over a disc in a disc drive while maintaining servo loop stability. The apparatus includes an actuator-head assembly having a large-scale actuator and a micro-actuator that are both able to move the head over the disc. A saturation adjustment component detects when a micro-actuator controller is producing a micro-actuator control value that will saturate the micro-actuator. Using the micro-actuator control value, the saturation adjustment component generates a saturation error value. An adaptive anti-windup circuit transfers control to the large-scale actuator when the saturation error value is generated by the saturation adjustment component.

Abstract: A method and apparatus for compensating for written-in repeatable runout in a disc drive is provided. Compensation values are determined through an iterative learning process in which parameters of the learning process such as learning gain, servo loop gain, etc. are functions of the iteration number. The learning process also employs a nominal double integrator model of an actuator of the disc storage system. The learning process is also a function of a zero-phase low-pass filter.

Abstract: Briefly, a preferred embodiment of the present invention includes an apparatus for tuning a regulator in a process controller. The digitized output from a standard relay and a parasitic relay are fed through digital to analog converter providing signals at 0.5&ohgr;c, &ohgr;c and 1.5&ohgr;c to the process, where &ohgr;c is the process critical frequency. The apparatus records the digitized relay output u′ and the digitized process output y′ until stationary oscillations are reached. The outputs u′ and y′ are then used to calculate the process frequency response at 0.50&ohgr;c, &ohgr;c and 1.5&ohgr;c. This data is then used to design the regulator, the output of which is converted to analog form and inputted to control the process.

Abstract: An apparatus and method for improving servo loop performance in a disc drive storage system are provided. The servo loop includes a voice coil motor actuator that moves the head in response to a received servo control signal. A sensor, located in the head, senses servo information located on the disc and produces a servo signal therefrom. The servo signal is combined with a reference signal to produce a position error signal. A servo controller receives the position error signal and responsively produces the servo control signal. The servo controller includes a drive signal generator that receives the position error signal and responsively produces a driving energy signal. A vibration damping circuit receives the driving energy signal and responsively produces the servo control signal.

Abstract: A method and apparatus are provided for positioning a head over a disc in a disc drive while maintaining servo loop stability. The apparatus includes an actuator-head assembly having a large-scale actuator and a micro-actuator that are both able to move the head over the disc. A saturation adjustment component detects when a micro-actuator controller is producing a micro-actuator control value that will saturate the micro-actuator. Using the micro-actuator control value, the saturation adjustment component generates a saturation error value. An adaptive anti-windup circuit transfers control to the large-scale actuator when the saturation error value is generated by the saturation adjustment component.

Abstract: Many parallel tracks on a storage surface of a data handling device are arranged in a longitudinal direction. Each track has a track center comprising reference points for fine lateral positioning. Each successive pair of track centers has a succession of lateral offset distance having an average. Because there are many successive pairs of tracks, there are many average lateral offset distances defining a statistical distribution having a variance.

Abstract: Steps for isolating and correcting total written-in repeatable run-out error written into servo sectors of a disc drive include, determining a total repeatable run-out error value for each servo sector, isolating a repeatable error value component of the total written-in repeatable run-out error value for each servo sector, removing the repeatable error value component from total written-in repeatable run-out error value to provide a non-repeatable error value component of the total written-in repeatable run-out error value for each servo sector, providing both the repeatable and non-repeatable error value components to a processor for generation of compensation signals, and applying the compensation signals into a servo control circuit of control loop of the disc drive using compensation circuits to compensate for each component of the total written-in repeatable run-out error.

Abstract: Linearizing hysteresis of a microactuator for a disc drive by modeling the microactuator with a first polynomial equation to provide a linear displacement response of the microactuator responding to an applied voltage, deriving a set of constants from a plurality of burst patterns for use with the first polynomial equation to provide a set of variables for use in resolving the second polynomial equation to provide a set of equations from which a set of constants can be derived for use by the second polynomial equation to provide a voltage to the microactuator to displace the microactuator by a predetermined incremental distance.

Abstract: A disc drive including rotatable disc surface adjacent a positionable read/write head having a write element offset from a read element in one direction across the rotatable disc surface from an outer diameter of the disc surface to an inner diameter of the disc surface for writing head position control fields by steps for controlling writing of second head position control fields on a second portion of the disc surface while reading head position control fields written on a first portion of the disc surface, using the read element, to augment position-control of the write element being controlled by a position information writing apparatus, while writing the second head position control field to the second portion of the disc surface.

Abstract: A method of calibrating magnetoresistive (MR) head geometry for a product head in a selfservo writing disc drive includes the steps of writing a first burst at an inner diameter of a disc surface using the write head of the product head. Next, the first burst is read using the MR read head of the product head, and a first read amplitude of the first burst is determined. From the first read amplitude of the first burst, it is determined which one of a multiple different sets of subsequent inner diameter steps to perform. Then, the one of the multiple different sets of subsequent inner diameter steps is performed to determine a read head width, a write head width, and a read-write offset between the read head and the write head.