Abstract: An apparatus and method for compensating actuator arm oscillation induced by resonance mode excitation during a seek in a disc drive data handling system. The actuator arm supports a head adjacent a recording surface, and a servo loop controls the position of the actuator arm. A frequency of actuator arm oscillation is identified, after which a seek is initiated to move the head from an initial track to a destination track on the recording surface. A position error signal (PES) is generated to indicate position of the head relative to the destination track, and a compensation signal is generated by a filter based on the PES and the frequency of oscillation of the actuator arm. The compensation signal is adapted to remove a component of the PES arising from the actuator arm oscillation, and is applied to the servo loop as the head is settled onto the destination track.

Abstract: An apparatus and method for compensating actuator arm oscillation induced by resonance mode excitation during a seek in a disc drive data handling system. The actuator arm supports a head adjacent a recording surface, and a servo loop controls the position of the actuator arm. A frequency of actuator arm oscillation is identified, after which a seek is initiated to move the head from an initial track to a destination track on the recording surface. A position error signal (PES) is generated to indicate position of the head relative to the destination track, and a compensation signal is generated by a filter based on the PES and the frequency of oscillation of the actuator arm. The compensation signal is adapted to remove a component of the PES arising from the actuator arm oscillation, and is applied to the servo loop as the head is settled onto the destination track.

Abstract: A method and apparatus for estimating position and speed of a read/write head in a disc drive, based upon the back EMF of the voice coil motor involves estimating the voltage across the voice coil motor and estimating the voltage across a current-sensor resistor in the voice coil circuit, preferably with a differential amplifier. Further, a coil resistance voltage is estimated by measuring the voltage across the current-sensor resistor with a differential amplifier and amplifying the voltage across the current-sensor resistor by a gain value. Finally, the combined voltage across the current-sensor resistor and the characteristic coil resistance is subtracted from the voltage across the voice coil motor, yielding the back EMF of the voice coil motor. The back EMF is representative of head velocity which may be integrated to yield position. Accordingly, the back EMF can be used to control the speed and position of the read/write head.