Patent ID: 6819521
Filing Date: 2004-11-16
Classification: G11B

Abstract:
In a data handling system which uses an actuator assembly to support a head adjacent a recording surface and a servo loop which generates a position error signal to controllably position the head, a method for reducing repeated runout position error comprising error in the position of the head that is repeated over each revolution of the recording surface, comprising steps of:(a) identifying a frequency of rotation of the recording surface; (b) configuring a filter to provide a notch in an error sensitivity function relating the position error signal to the repeated runout position error, wherein the notch is nominally centered at the frequency of rotation of the recording surface; (c) receiving a position error signal sample having a component of the repeated runout position error; (d) using the filter configured in step (b) to filter the position error signal sample to generate a compensation signal sample configured to remove the component of the repeated runout position error without the use of different compensation values stored in memory for each position error signal sample; and (e) applying the compensation signal to the servo loop.