Abstract: A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk. The disk drive further comprises control circuitry configured to measure a rotation speed of the spindle motor, generate a feed-forward control based on the measured rotation speed, and spin-up the spindle motor based on the feed-forward control.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor operable to rotate the disk. The disk drive comprises control circuitry configured to a rotation speed of the spindle motor, generate a gain as a function of the measured rotation speed, wherein the function comprises a polynomial having a degree greater than one, and spin-up the spindle motor based on the gain.

Abstract: A disk drive is disclosed comprising a disk, a head coupled to a distal end of an actuator arm, a voice coil motor (VCM) operable to rotate the actuator arm about a pivot in order to actuate the head radially over the disk, and a ramp located near an outer edge of the disk for parking the head. A first back electromotive force (BEMF) voltage of the VCM is measured, and a current is applied to the VCM for a first interval in order to move the actuator arm in a first radial direction. After the first interval, a second BEMF voltage of the VCM is measured, and whether the head is parked is detected in response to the first and second BEMF voltages.

Abstract: A disk drive is disclosed comprising a disk and a head actuated over the disk by a voice coil motor (VCM) comprising a voice coil, wherein the VCM is controlled by a VCM control loop comprising an IR voltage detector. The IR voltage detector is updated by measuring a first back EMF voltage of the voice coil, and after measuring the first back EMF voltage, applying a first control current to the voice coil for a first interval and applying a second control current to the voice coil for a second interval. After the second interval, a second back EMF voltage is measured, and a delta voltage is computed relative to a difference between the first back EMF voltage and the second back EMF voltage. The IR voltage detector is adjusted in response to the delta voltage and at least one of the first and second control currents.

Abstract: A disk drive is disclosed comprising an IR voltage detector operable to detect a resistive voltage due to a resistance of a voice coil in a voice coil motor, and a BEMF detector operable to subtract the resistive voltage from the voice coil voltage to generate a BEMF voltage. A gain Gr of the IR voltage detector is calibrated by: (a) adjusting a control current applied to the voice coil; (b) adjusting the gain Gr; (c) detecting and saving the BEMF voltage corresponding to the adjusted gain Gr; (d) repeating steps (b) and (c) at least once; (e) repeating steps (a) through (d) at least once; and (f) selecting an operating gain Gr of the IR voltage detector in response to the adjusted control currents, the adjusted gains Gr, and the saved BEMF voltages.