Patent ID: 7158334

Claim:
A disk drive comprising: an actuator to position a head at a target position on a disk medium; a first controller which controls the actuator by feedback control to position the head at the target position on the disk medium based on position error information between the target position and a position of the head; and a second controller which outputs a disturbance compensation value to the first controller, wherein the second controller includes: an amplitude detection unit which detects an amplitude of narrow-band disturbance from the position error information, using an absolute value computing unit for computing an absolute value of the position error information and a low-pass filter for determining the amplitude from the absolute value; a phase detection unit which detects a phase of the narrow-band disturbance from the position error information; and a unit which computes the disturbance compensation value for eliminating the narrow-band disturbance based on each detection result of the amplitude detection unit and the phase detection unit.