MODELING POSITION ERROR NONLINEARITY TO IMPROVE SERVO PERFORMANCE

摘要

An apparatus and method are disclosed for improving servo performance of a disc drive. The disc drive includes a head adjacent a rotatable disc on which data are stored on a plurality of tracks. A servo circuit is provided to control the position of the head by generating an actual (raw) position error signal (PES) nominally characterized as nonlinear over a portion of the width of a selected track and indicative of position of the head relative to the selected track. The servo circuit further generates a predicted PES as an approximation of the actual PES, and then controls head position through summation of the actual PES with the predicted PES. The servo circuit includes a burst signal generator which generates predicted burst signals as approximations of actual burst signals determined from readback signals from the head as the head reads servo burst patterns on the disc. Substantial portions of the servo circuit operation are preferably carried out by a programmable processor device, such as a digital signal processor.