Patent ID: 7177113
Filing Date: 2007-02-13
Classification: G11B

Abstract:
1. A method for operating a disk drive, the disk drive including (a) a rotatable magnetic recording disk having a plurality of concentric data tracks containing servo positioning information; (b) a recording head movable across the disk, the head being capable of reading data and servo positioning information in the data tracks; (c) a voice-coil-motor (VCM) for moving the head; (d) a rotational vibration (RV) sensor for sensing rotational vibration of the disk drive; (e) a servo control processor responsive to a position error signal (PES) from the servo positioning information for generating a VCM control signal, the PES representing the off-track position of the head; and (f) a feedforward controller responsive to a signal from the RV sensor for generating a compensation signal to be summed with the VCM control signal; the processor-implemented method comprising: calculating an estimated off-track position of the head from the RV sensor signal, said calculated estimated off-track position of the head representing a PES threshold; comparing the PES to said PES threshold to generate a PES comparison value, if the compensation signal is disabled, enabling the compensation signal in response to the comparison value; and if the compensation signal is enabled, disabling the compensation signal in response to the comparison value.