Abstract: An actuator control system for a two-stage actuator system of a disc drive has a first, or primary, stage actuator consisting of a voice coil motor that positions the head relative to a disc and a microactuator that alters the actuator system without operation of the voice coil motor. A control loop includes a controller responsive to seek commands to operate the voice coil motor, thereby moving the head relative to the disc. An active damping circuit is coupled to the head to operate the microactuator to damp resonance modes of the actuator system.

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 data storage device has optimized track densities for each of a plurality of data storage surfaces. Each storage surface of the data storage device has a plurality of adjacent data storage tracks positioned at a track density defined by the width of the confronting head. Head/surface combinations are arranged so that the average of the track densities of all of the surfaces equals a selected nominal track density for the data storage device. A ratio between the track density and the servo band density is stored for each data storage surface. During operation of the storage device, the track density and other parameters necessary to the operation of the device are re-calculated from the ratio and established device parameters.

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 first method for detecting movement of an actuator includes supplying a demand current to a voice coil motor of the actuator (A.sub.1), sampling a voice coil motor voltage (B.sub.1), performing a slope detection of a voice coil motor voltage function (C.sub.1) and extrapolating the voice coil motor function (D.sub.1) to identify a change in slope of the voice coil motor function.A second method for detecting movement of an actuator includes supplying a continuously increasing current ramp to the voice coil motor of an actuator (A.sub.2), measuring a back e.m.f. voltage of the voice coil motor (B.sub.2), performing a change in slope detection of a back e.m.f. voltage function (C.sub.2) and integrating the back e.m.f. voltage function (D.sub.2) to determine movement of the actuator.