Granted Patent B1

US 9,269,386 · App. 14/563,837 · Granted Feb 23, 2016

Abstract

Claims (69)

1. A data storage device comprising:

a disk comprising tracks defined by servo sectors;

a head; and

control circuitry configured to:

measure a location of the head over the disk based on the servo sectors;

generate a position error signal (PES) representing a difference between a target location for the head and the measured location for the head;

generate an actuator control signal (ACS) in response to the PES;

generate a disturbance compensation signal (DCS) based on the PES and the ACS;

filter the DCS with a disturbance observer filter;

adjust the ACS based on an output of the disturbance observer filter;

actuate the head over the disk based on the adjusted ACS;

filter the DCS with a plurality of band-pass filters;

filter an output of one of the band-pass filters with a peak detection filter configured to detect a peak frequency corresponding to a peak in a frequency response of the band-pass filter; and

adjust the disturbance observer filter based on the peak frequency.

2. The data storage device as recited in claim 1 , wherein the peak detection filter comprises an adaptive notch filter.

3. The data storage device as recited in claim 2 , wherein the control circuitry is further configured to detect the peak frequency by adjusting a center frequency of the adaptive notch filter.

4. The data storage device as recited in claim 3 , wherein the control circuitry is further configured to adjust the center frequency of the adaptive notch filter according to:

θ c ( k+ 1)=θ c ( k )+μ· e ( k )· x 1 ( k )

where:

θ c (k) represents the center frequency of the adaptive notch filter;

μ is a learning coefficient;

e(k) represents an output of the adaptive notch filter; and

x 1 (k) represents a regressor signal corresponding to a first state of the adaptive notch filter.

5. The data storage device as recited in claim 4 , wherein the adaptive notch filter comprises an all-pass lattice filter.

6. The data storage device as recited in claim 4 , wherein the control circuitry is further configured to adapt the learning coefficient μ.

7. The data storage device as recited in claim 5 , wherein the control circuitry is further configured to adapt the learning coefficient μ.

8. The data storage device as recited in claim 3 , wherein the control circuitry is further configured to adjust the center frequency of the adaptive notch filter according to:

θ c ( k+ 1)=θ c ( k )+( e ( k )· x 1 ( k ))>>η( k )

where:

θ c (k) represents the center frequency of the adaptive notch filter;

η(k) is an adaptive learning term;

e(k) represents an output of the adaptive notch filter; and

x 1 (k) represents a regressor signal corresponding to a first state of the adaptive notch filter.

9. The data storage device as recited in claim 8 , wherein the control circuitry is further configured to adapt the learning term η(k) based on:

η( k+ 1)=γ·η( k )+2(1−γ)log 2(abs( x 1 ( k )))

where γ represents a learning coefficient.

10. A method of operating a data storage device, the method comprising:

measuring a location of a head over a disk based on servo sectors recorded on the disk;

generating a position error signal (PES) representing a difference between a target location for the head and the measured location for the head;

generating an actuator control signal (ACS) in response to the PES;

generating a disturbance compensation signal (DCS) based on the PES and the ACS;

filtering the DCS with a disturbance observer filter;

adjusting the ACS based on an output of the disturbance observer filter;

actuating the head over the disk based on the adjusted ACS;

filtering the DCS with a plurality of band-pass filters;

filtering an output of one of the band-pass filters with a peak detection filter configured to detect a peak frequency corresponding to a peak in a frequency response of the band-pass filter; and

adjusting the disturbance observer filter based on the peak frequency.

11. The method as recited in claim 10 , wherein the peak detection filter comprises an adaptive notch filter.

12. The method as recited in claim 11 , further comprising detecting the peak frequency by adjusting a center frequency of the adaptive notch filter.

13. The method as recited in claim 12 , further comprising adjusting the center frequency of the adaptive notch filter according to:

θ c ( k+ 1)=θ c ( k )+μ· e ( k )· x 1 ( k )

where:

θ c (k) represents the center frequency of the adaptive notch filter;

μ is a learning coefficient;

e(k) represents an output of the adaptive notch filter; and

x 1 (k) represents a regressor signal corresponding to a first state of the adaptive notch filter.

14. The method as recited in claim 13 , wherein the adaptive notch filter comprises an all-pass lattice filter.

15. The method as recited in claim 13 , further comprising adapting the learning coefficient μ.

16. The method as recited in claim 14 , further comprising adapting the learning coefficient μ.

17. The method as recited in claim 12 , further comprising adjusting the center frequency of the adaptive notch filter according to:

θ c ( k+ 1)=θ c ( k )+( e ( k )· x 1 ( k ))>>η( k )

where:

θ c (k) represents the center frequency of the adaptive notch filter;

η(k) is an adaptive learning term;

e(k) represents an output of the adaptive notch filter; and

x 1 (k) represents a regressor signal corresponding to a first state of the adaptive notch filter.

18. The method as recited in claim 17 , further comprising adapting the learning term η(k) based on:

η( k+ 1)=γ·η( k )+2(1−γ)log 2(abs( x 1 ( k )))

where γ represents a learning coefficient.

Assignments (8)