Applying an adaptive feed-forward algorithm as a frequency selective filter in a closed loop disk drive servo system in order to compensate for periodic perturbations which otherwise appear in the servo system position error signal

摘要

A method for applying an adaptive feed-forward waveform correction to a primary servo loop compensation signal in a rotating data storage apparatus. A position error signal is used to determine a fixed feed- forward correction upon initialization or other predetermined conditions. An adaptive feed-forward waveform correction is periodically determined by adding a scaled version of the position error signal to the stored adaptive feed-forward value, and then processing the resulting sum through a frequency selective filter. The stored adaptive feed-forward correction is then updated with this new result. Simultaneously, the updated adaptive feed-forward correction is combined with the fixed feed- forward correction and the position error signal to generate a primary servo loop compensation signal for controlling the read/write head of the data storage apparatus.