Patent ID: 7012777

Claim:
A disk drive having a rotatable magnetic recording disk with a plurality of data tracks and a recording head movable across the disk surface for reading and/or writing data in the tracks, and wherein the tracks contain head position information detectable by the head and the head experiences a track misregistration (TMR) frequency response as a result of out-of-plane vibration of the rotating disk, the disk drive comprising: an actuator for moving the head across the disk surface; a head position feedback controller responsive to position information detected by the head for generating a head position control signal; a capacitive sensor facing the disk surface; a capacitance sensing circuit coupled to the sensor for generating a signal representative of the distance between the sensor and the disk surface; and a feedforward controller responsive to the distance signal for generating a correction signal, the correction signal being combined with the head position control signal to generate an actuator control signal, the feedforward controller having gain and phase characteristics to substantially match the frequency response from the out-of-plane vibration to the TMR while accounting for the effects of the dynamics of the capacitive sensor and actuator.