Patent ID: 7595953
Filing Date: 2009-09-29
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 read/write head movable across the disk, the head being capable of reading data and servo positioning information in the data tracks and writing data in the data tracks; (c) a voice-coil-motor (VCM) for moving the head; (d) a VCM driver for supplying electrical current to the VCM; (e) a power supply for powering the VCM driver; (f) an electrical disturbance (ED) sensor for detecting ED to the VCM driver; (g) a rotational vibration (RV) sensor for sensing RV of the disk drive; (h) 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; (i) an ED feedforward controller responsive to a signal from the ED sensor for generating an ED compensation signal to be summed with the VCM control signal; and (j) a RV feedforward controller responsive to a signal from the RV sensor for generating a RV compensation signal to be summed with the VCM control signal; the processor-implemented method comprising: determining if the PES is greater than a predetermined PES threshold, thereby indicating track misregistration (TMR); comparing the averaged ED sensor signal to an ED threshold; if the PES is greater than said PES threshold and said averaged ED sensor signal is not greater than said ED threshold, turning the RV compensation signal on, whereby the RV compensation responds substantially only to actual RV sensed by the RV sensor.