Disc drive resonance disturbance cancellation filter

Abstract

An apparatus and method for canceling nonrepeatable runout position error in a disc drive. Pursuant to the method, a frequency of a specified nonrepeatable runout disturbance is determined. A position error signal indicative of a position of a read/write head relative to a track is received. A signal is generated based upon the frequency of the specified nonrepeatable runout disturbance and the received position error signal. The generated signal is applied to the servo loop. Applying the generated signal to the servo loop cancels a component of the position error signal arising from the specified nonrepeatable runout disturbance. In an illustrative embodiment, applying the generated signal to the servo loop produces a notch in an error sensitivity function relating the position error signal to a general nonrepeatable runout disturbance, the notch being centered at the frequency of the specified nonrepeatable runout disturbance.

Dependencies are inferred from the claim text.