Method and apparatus for feedforward cancellation using a peak detector
AssigneeSeagate Technology LLC
InventorHai T. Ho
Life of this patent
Estimating the term…
Abstract
A method and apparatus are provided for generating a feedforward cancellation signal for a next sector of a disc in a disc drive. To form the cancellation signal, the method and apparatus estimate the phase and frequency of a nonrepeatable runout error in a position error signal. A peak detector is then used to identify a peak amplitude of the nonrepeatable runout error for a current sector. Using the peak amplitude, an amplitude is determined for the cancellation signal for the next sector. A time-varying signal is then evaluated based on the estimated phase and frequency and the result of the evaluation is multiplied by the amplitude to produce the cancellation signal.
Claims11
A method of generating a feedforward cancellation value for canceling nonrepeatable runout position error in a disc drive, the method comprising steps of:
- (a) generating a position error signal based in part on the position of a head relative to a track on a disc in the disc drive;
- (b) estimating a phase and frequency for a cancellation signal based at least in part on the position error signal;
- (c) detecting a peak in the position error signal;
- (d) estimating an amplitude for the cancellation signal from the detected peak;
- and
- (e) generating the cancellation value based on the amplitude, phase and frequency for the cancellation signal.
In a disc drive, a servo system for positioning a head over a track, the servo system comprising:
- a controller capable of generating a control signal based in part on a position error signal;
- an actuator-head assembly comprising an actuator and the head and capable of moving the head based at least in part on the control signal from the controller and capable of generating a position error signal based on the position of the head over a track;
- and
- a feedforward cancellation component capable of receiving a position error signal for a current sector and capable of producing a cancellation signal for a next sector based in part on the position error signal, the feedforward cancellation component comprising:
- a frequency estimator capable of estimating the frequency of a nonrepeatable runout error in the position error signal;
- a peak detector capable of identifying a peak in the position error signal;
- and
- a value calculator capable of generating the cancellation signal at least in part by evaluating a time-varying function using the estimated frequency and multiplying the result of the evaluation by an amplitude that is based on the identified peak in the position error signal.
A disc drive for storing data in tracks along a disc, the disc drive comprising:
- a servo loop for positioning a head relative to a track;
- and
- feedforward cancellation means coupled to the servo loop for canceling nonrepeatable runout positioning errors using a peak detector.
Dependencies are inferred from the claim text.