Patent ID: 6900958
Filing Date: 2005-05-31
Classification: G11B

Abstract:
1. A method for improving head position accuracy in a disk drive during track following of concentric data storage tracks on a rotating disk's storage surface through real-time identification of external vibration, the method comprising the steps, of: seeking to a predetermined data storage track; following the predetermined data storage track using a servo control loop having a nominal gain and being responsive to a position error signal (PES) generated during track following; waiting a vibration detection delay period after the seek to the predetermined data storage track; after the vibration detection delay period, counting occurrences of the PES exceeding a write unsafe (WUS) limit to generate a WUS limit exception count, and determining a property of a variance of a predetermined number of temporally accumulated spectral power values, within a predetermined frequency band, generated from the PES during track following; and increasing the gain of the servo control loop, within the predetermined frequency band, from the nominal gain to a vibration gain, if the WUS limit exception count exceeds a first threshold and if the property of the variance exceeds a second threshold, to attenuate the effect of external vibration on the position of the head during track following.