Patent ID: 6738220
Filing Date: 2004-05-18
Classification: G11B

Abstract:
A hard disk device comprising:a rotatable disk having a magnetic recording media wherein the rotatable disk defines a plurality of concentric servo tracks; a pivotable actuator that is movable with respect to the rotatable disk wherein the pivotable actuator is subject to a first bias force wherein the first bias force has a history component that varies at least in part, based upon the history of previous movements of the pivotable actuator; a transducer positioned on the actuator so as to be movable with respect to the disk so as to be positionable on a selected servo track of the plurality of concentric servo tracks; a controller that induces bias outputs to be applied to the pivotable actuator during positioning of the actuator during a selected seek operation wherein the controller induces a first bias output to be applied to the actuator to position the actuator with respect to the rotatable disk so as to position the transducer on a selected servo track of the plurality of servo tracks wherein the controller monitors at least one inflection length that is defined as the total number of tracks traversed during a plurality of seek operations between changes in direction of the pivotable actuator prior to the selected seek operation and determines the magnitude of the first bias output by determining a first magnitude value indicative of the approximate bias needed to position the actuator so as to position the transducer on the selected servo track and then offsetting the first magnitude value by a history offset value that corresponds to the history component of the first bias force exerted on the actuator and wherein the history offset is determined based upon the monitored at least one inflection length.