Patent ID: 6369974
Filing Date: 2002-04-09
Classification: G11B

Abstract:
In a disk drive having a disk, a transducer, and an embedded servo control system including a servo sector having a first burst pair and a second burst pair, a method of constructing a position signal reflecting a position of the transducer relative to the servo sector, the method comprising the steps of:obtaining a measured position p relative to a first burst pair centerline wherein the measured position p ranges within a first fractional PES segment from a first measured endpoint position pSTART on a first side of the first burst pair centerline to a second measured endpoint position pEND on a second side of the first burst pair centerline, the first and second measured endpoint positions being equal in magnitude and opposite in sign such that the first fractional PES segment is continuous at a segment junction formed with a second fractional PES segment associated with a second burst pair centerline located adjacent to the first burst pair centerline; and deriving an estimated position {circumflex over (x)} that more closely corresponds to a true position x by compensating for nonlinearities in the measured position p at positions with values in between the first and second measured endpoint positions, while keeping the first and second endpoint values equal in magnitude and opposite in sign to keep the first fractional PES segment continuous with the second fractional PES segment, wherein the servo control system provides a primary position signal waveform P from the first burst pair and a quadrature position signal waveform Q from the second burst pair and wherein the step of obtaining a measured position p relative to a first burst pair centerline comprises the step of constructing the fractional PES segment from a ratio of the P and Q position signal waveforms, and wherein the step of constructing a fractional PES segment from a ratio of the P and Q position signal waveforms comprises the steps of: determining whether the transducer is closer to the first burst pair centerline or the second burst pair centerline; and if the transducer is closer to the first burst pair centerline, constructing a fractional PES segment from a first ratio of the P and Q position signal waveforms; else if the transducer is closer to the second burst pair centerline, constructing the fractional PES segment from a second ratio of the P and Q position signal waveforms.