Patent ID: 7088547

Claim:
A disk drive comprising: (a) a disk comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors and a plurality of embedded servo sectors; (b) an actuator arm; (c) a head coupled to a distal end of the actuator arm; (d) a voice coil motor (VCM) for rotating the actuator arm about a pivot in order to actuate the head over the disk; and (e) control circuitry for generating a control signal applied to the VCM in response to a position error signal (PES) generated from reading the embedded servo sectors and a feed-forward compensation value that compensates for a repeatable runout (RRO) disturbance, the feed-forward compensation value generated for each servo sector in response to an RRO estimate Ŝ computed recursively for each servo sector according to: S ^ n + 1 = S ^ n - λ ⁡ [ S ^ n - 1 n ⁢ ∑ i = 1 n ⁢ ⁢ PES i ] wherein: λ is a predetermined fraction; PES i is the position error signal generated for a selected servo sector during an ith revolution of the disk; and n represents a number of disk revolutions.