US Patent 7859787 Disk drive and controlling method thereof

Embodiments of the present invention provide a disk drive capable of appropriately measuring non-linearity in a head position control system, and a control method therefore. According to one embodiment, a magnetic disk drive inputs a reference signal SR into a voice coil motor, inputs into the voice coil motor a control signal SC in which a harmonic component resulting from the reference signal SR is suppressed, and measures an error signal PES that may be obtained in the state where the reference signal SR and the control signal SC, in which the harmonic component is suppressed, are input in the voice coil motor.