Abstract: The operational bandwidth of a servo control circuit can be increased using a plurality of servo processors that handoff between them the responsibility for controlling head positioning in response to sequentially occurring servo patterns.

Abstract: The operational bandwidth of a servo control circuit can be increased using a plurality of servo processors that handoff between them the responsibility for controlling head positioning in response to sequentially occurring servo patterns.

Abstract: An apparatus and method are disclosed for improving servo performance of a disc drive. The disc drive includes a head adjacent a rotatable disc on which data are stored on a plurality of tracks. A servo circuit is provided to control the position of the head by generating an actual (raw) position error signal (PES) nominally characterized as nonlinear over a portion of the width of a selected track and indicative of position of the head relative to the selected track. The servo circuit further generates a predicted PES as an approximation of the actual PES, and then controls head position through summation of the actual PES with the predicted PES. The servo circuit includes a burst signal generator which generates predicted burst signals as approximations of actual burst signals determined from readback signals from the head as the head reads servo burst patterns on the disc.

Abstract: Apparatus and method for providing a linearized position error signal in a disc drive. A first servo position error signal is generated by the disc drive as a selected combination of servo burst signals received as a disc drive head passes over servo burst fields of a selected track, the first servo position error signal having a magnitude indicative of the position of the head relative to the selected track. A second servo position error signal is also generated by the disc drive as a selected combination of the servo burst signals, the magnitude of the second servo position error signal being different from the magnitude of the first servo position error signal for at least a portion of the width of the selected track.

Abstract: Method and apparatus for compensating for errors in the location of servo frames in a disc drive, the servo frames providing control inputs to a servo loop of the disc drive. Each servo frame includes an additional compensation field to which a compensation term is written, the compensation term indicative of the average radial error in the location of the servo frame. The compensation term is determined by measuring the radial distance between adjacent servo frames over a plurality of revolutions of the disc and averaging these measured radial distances. The compensation terms are thereafter used in conjunction with position information from the servo frames to control the position of the head. The compensation term facilitates the elimination of repeatable, random errors in the locations of the servo frames, causing the head to nominally follow a circular path about the disc, regardless of the errors in the locations of the servo frames.