Patent ID: 7688541

Claim:
An apparatus to cancel repeatable runout signals, the apparatus comprising: a signal processing module configured to receive a position error signal and to output a position compensated signal; a feed forward module comprising one or more harmonic detectors, one or more integrators, and one or more harmonic sources, wherein the feed forward module is configured to receive the position error signal and to output one or more cancellation signals configured to cancel one or more repeatable runout components from the position error signal when combined with the position compensated signal, and further wherein a stable gain for the feed forward module is selected using one or more mathematical equations by modeling the apparatus as a feedback loop; a combining module configured to combine the position compensated signal and the cancellation signals into a position command signal; and a feedback module configured to receive the position command signal and to output the position error signal; wherein at least a portion of the signal processing module, the feed forward module, the combining module, and the feedback module comprise at least one of logic hardware elements and executable code, the executable code stored on one or more computer readable media.