Patent ID: 6580579
Filing Date: 2003-06-17
Classification: G11B

Abstract:
In a disc drive servo system comprising a servo loop adapted to position a read/write head relative to a disc surface based upon a position error signal indicative of a difference between an actual position of the read/write head relative to the disc surface and a desired position of the read/write, a method of attenuating an effect of rotational vibration on the positioning of the read/write head, comprising steps of:(a) measuring a rotational acceleration of the disc drive body; (b) providing a rotational acceleration signal indicative of the measured rotational acceleration to an adaptive filter adapted to further receive the position error signal and to produce a feedforward signal adapted to offset a disturbance to the read/write head position caused by rotational vibration, the adaptive filter having parameters that are adjustable based upon the rotational acceleration signal, the position error signal and a transfer function relating an actual position signal, indicative of the actual position of the read/write head relative to the disc surface, to the feedforward signal; (c) providing the feedforward signal to the servo loop; (d) estimating a transfer function relating the actual position signal to the feedforward signal off-line; and (e) storing the estimate of the transfer function in memory for access by the adaptive filter during operation.