Feedforward compensation for multi-actuator hard drives

• US 9,911,442 B1
• Filed: 11/23/2016
• Issued: 03/06/2018
• Est. Priority Date: 11/23/2016
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Kharisov, Evgeny, Wernow, Josiah Natan, Haapala, Kenneth A., Morris, John C., Sosseh, Raye A.
• Primary Examiner(s): Young, Wayne
• Assistant Examiner(s): Habermehl, James L
• Application Number:
  US15/360,540
• Time in Patent Office: 468 Days
• Field of Search: 360 55, 360 75, 360 7704, 360 7805, 360 7809, 360 7812
• CPC Class Codes: G11B 5/5547 "Seek" control and circuits therefor G11B5/5556 takes precedence
• CPC Class Codes: G11B 5/5552 using fine positioning means for track acquisition separate from the coarse (e.g. track changing) positioning means
• CPC Class Codes: G11B 5/5565 system adaptation for compensation of variations of physical parameters, e.g. temperature
• CPC Class Codes: G11B 5/5578 Multiple actuators addressing the same disk, e.g. to improve data rate or access rate
• CPC Class Codes: G11B 5/5582 system adaptation for working during or after external perturbation, e.g. in the presence of a mechanical oscillation caused by a shock

Abstract

An apparatus includes a first controller, a second controller, and a coupling compensator. The first controller is configured to generate a first voice coil motor (VCM) control signal in response to a first position error signal. The second controller is configured to generate a second VCM control signal in response to a second position error signal. The coupling compensator is configured to generate a first feedforward correction signal in response to the first VCM control signal. The first feedforward correction signal modifies the second VCM control signal to generate a modified second VCM control signal.

Claims

1. An apparatus comprising:

a first controller configured to generate a first voice coil motor (VCM) control signal in response to a first position error signal;

a second controller configured to generate a second VCM control signal in response to a second position error signal; and

a coupling compensator configured to generate a first feedforward correction signal in response to the first VCM control signal and in response to precomputed future values of a feedforward seek signal, wherein the first feedforward correction signal modifies the second VCM control signal to generate a modified second VCM control signal.

2. The apparatus of claim 1, wherein the feedforward seek signal is a feedforward seek signal for the first VCM.

3. The apparatus of claim 1, further comprising:

a notch filter configured to filter targeted frequencies of the feedforward seek signal.

4. The apparatus of claim 3, wherein the targeted frequencies are in a kHz range.

5. The apparatus of claim 3, further comprising:

a pseudo-filter configured to correct for phase error introduced by the notch filter.

6. The apparatus of claim 1, wherein the coupling compensator is further configured to output a microactuator feedforward correction signal that modifies a second microactuator control signal.

7. The apparatus of claim 6, wherein the coupling compensator includes a bandpass filter configured to generate the microactuator feedforward correction signal.

8. The apparatus of claim 1, wherein the first VCM control signal is used for a track-seeking operation, and wherein the second VCM control signal is used to a track-following operation.

9. The apparatus of claim 1, further comprising:

a first actuator assembly including a first VCM, a first microactuator, and a first read/write head; and

a second actuator assembly including a second VCM, a second microactuator, and a second read/write head.

10. The apparatus of claim 9, wherein the modified second VCM control signal is used to position the second read/write head.

11. The apparatus of claim 1, wherein the first and second controllers each include a VCM controller and a microactuator controller.

12. The apparatus of claim 1, wherein the first feedforward correction signal modifies the first VCM control signal to generate a modified first VCM control signal.

13. An apparatus comprising:

a first controller configured to generate a first voice coil motor (VCM) control signal in response to a first position error signal;

a second controller configured to generate a second VCM control signal in response to a second position error signal;

a feedforward seek controller configured to generate a feedforward seek signal; and

a notch filter configured to suppress targeted frequencies of the feedforward seek signal to generate a filtered feedforward seek signal, wherein the filtered feedforward seek signal modifies the first VCM control signal to generate a modified first VCM control signal.

14. The apparatus of claim 13, wherein the targeted frequencies are in a kHz range.

15. The apparatus of claim 13, wherein a targeted frequency is determined in response to a measured temperature.

16. The apparatus of claim 13, further comprising:

a pseudo-filter configured to correct for phase error introduced by the notch filter.

17. An apparatus comprising:

a first controller configured to generate a first voice coil motor (VCM) control signal in response to a first position error signal;

a second controller configured to generate a second VCM control signal in response to a second position error signal; and

a coupling compensator configured to generate a first feedforward correction signal in response to the first VCM control signal and in response to a vibration sensor signal, wherein the first feedforward correction signal modifies the second VCM control signal to generate a modified second VCM control signal.

18. The apparatus of claim 17, further comprising:

a feedforward seek controller configured to generate a feedforward seek signal; and

a notch filter configured to suppress targeted frequencies of the feedforward seek signal to generate a filtered feedforward seek signal, wherein the filtered feedforward seek signal modifies the first VCM control signal to generate a modified first VCM control signal.

19. The apparatus of claim 17, wherein the second controller is configured to generate a second microactuator control signal.

20. The apparatus of claim 19, wherein the coupling compensator is further configured to output a microactuator feedforward correction signal that modifies the second microactuator control signal.