Maxtor Corporation

Dave Finamore

Thomas O Melrose

Larry G Hutsell

Jim Hargarten

Farhad Navid

Andy Ottele

Disturbances to actuator control caused by external vibrations are corrected using feed-forward techniques that are selectively enabled or disabled based on signal values within a track follow loop. An increase in data integrity and reliability may be achieved by reducing off-track reads and writes caused by physical disturbances to disk drives during operation. Accelerometers detect external forces imparted on a disk and an acceleration feed-forward (AFF) signal is generated to compensate for disturbances to the location of a head caused by such external forces. Application of the AFF signal to an actuator may be based on whether signal values along the track follow loop exceed a certain threshold.

Acceleration feed-forward correction enabled or disabled based on track follow loop signals

A method and apparatus for the enhancement of embedded runout correction in a disk drive is provided. According to the present invention, embedded runout correction values are obtained by convolving a position error signal due to repeatable runout for a track with an inverse impulse response describing the response of a transducer head servo system to a given input. According to the present invention, the inverse impulse response is determined by introducing an impulse to a transducer head servo system, and measuring the response of the system in the time domain. The response is transformed to the frequency domain to form an error transfer function, the reciprocal is taken, and the function is transformed back into the time domain. The inverse impulse response, according to the present invention, is obtained for at least every transducer head in a disk drive capable of addressing a track for which embedded runout correction is desired. The embedded runout correction values may be calculated without the use of a servo track writer.

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Louisville, CO, United States of America

Dave Finamore