a control system rotates disks as information storage media to position a head in a disk drive that records or reproduces data . an actuator swings the head in the radial direction of the disk . positioning of the head is performed by a servo control system adjusting a drive current supplied to the actuator based on the value of the drive current and head position information . parameters for the actuator are estimated based on the head position information and the value of the drive current obtained when the head is vibrated at one or more frequencies in a plurality of positions . the estimated parameters are used to adjust input / output signals for the servo control system to correct the preset parameters for the control system .