Loop shaping methods and devices for disturbance observer in servo control systems

Patent metadata

Field	Value
Publication number	US-9928862-B1
Application number	US-201615280525-A
Country	US
Kind code	B1
Filing date	Sep 29, 2016
Priority date	Sep 29, 2016
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

An apparatus includes voice coil motor (VCM) control circuitry and microactuator control circuitry. The VCM control circuitry includes a VCM disturbance observer configured to generate a VCM disturbance compensation signal. The microactuator control circuitry includes a microactuator disturbance observer configured to generate a microactuator disturbance compensation signal. The VCM disturbance observer and the microactuator disturbance observer are decoupled from each other.

First claim

We claim:

1. An apparatus comprising:
voice coil motor (VCM) control circuitry comprising a VCM disturbance observer configured to generate a VCM disturbance compensation signal and a VCM controller configured to generate a VCM position signal to be modified by the VCM disturbance compensation signal to generate a final VCM control signal; and
microactuator control circuitry comprising a microactuator disturbance observer configured to generate a microactuator disturbance compensation signal and a microactuator controller configured to generate a microactuator position signal to be modified by the microactuator disturbance compensation signal to generate a final microactuator control signal,
wherein the VCM disturbance compensation signal is generated in response to the microactuator position signal.

2. The apparatus of claim 1 , wherein the VCM controller is configured to generate the VCM position signal in response to a position error signal, and wherein the microactuator controller is configured to generate the microactuator control signal in response to the position error signal.

3. The apparatus of claim 1 , wherein the microactuator position signal is subtracted from a signal representing an actual position of a read/write head to generate a compensated VCM actual position signal.

4. The apparatus of claim 3 , wherein the VCM disturbance compensation signal is generated in response to the compensated VCM actual position signal.

5. The apparatus of claim 3 , wherein the microactuator disturbance compensation signal is generated in response to the compensated VCM actual position signal.

6. The apparatus of claim 1 , wherein the final microactuator control signal is generated by subtracting the microactuator disturbance compensation signal from the microactuator control signal.

7. The apparatus of claim 1 , wherein the VCM disturbance observer includes at least one filter configured to generate the VCM disturbance compensation signal.

8. The apparatus of claim 7 , wherein the at least one filter is either a bandpass filter or a notch filter.

9. The apparatus of claim 1 , wherein the final VCM control signal is generated by subtracting the VCM disturbance compensation signal from the VCM control signal.

10. The apparatus of claim 1 , wherein the microactuator disturbance compensation signal is generated in response to the VCM position signal.

11. The apparatus of claim 1 , wherein the VCM disturbance observer and the microactuator disturbance observer are decoupled from each other.

12. A hard drive comprising:
a voice coil motor (VCM) controller configured to generate a VCM position signal;
a VCM disturbance observer configured to generate a VCM disturbance compensation signal to modify the VCM position signal to generate a final VCM control signal;
a microactuator controller configured to generate a microactuator position signal; and
a microactuator disturbance observer configured to generate a microactuator disturbance compensation signal to modify the microactuator position signal to generate a final microactuator control signal,
wherein the VCM disturbance compensation signal is generated in response to the microactuator position signal.

13. The hard drive of claim 12 , further comprising:
an actuator assembly coupled to a read/write head, wherein the actuator assembly positions the read/write head in response to the final VCM control signal.

14. The hard drive of claim 13 , further comprising:
a microactuator coupled to the actuator assembly and the read/write head, wherein the microactuator positions the read/write head in response to the final microactuator control signal.

15. The hard drive of claim 12 , wherein the VCM disturbance observer and the microactuator disturbance observer are decoupled from each other.

16. The hard drive of claim 12 , wherein the VCM disturbance observer includes at least one filter configured to generate the VCM disturbance compensation.

17. The hard drive of claim 16 , wherein the at least one filter is either a bandpass filter or a notch filter.

18. The hard drive of claim 12 , wherein the microactuator disturbance observer includes at least one filter configured to generate the microactuator disturbance compensation.

19. The hard drive of claim 18 , wherein the at least one filter is either a bandpass filter or a notch filter.

20. The hard drive of claim 12 , wherein the microactuator disturbance compensation signal is generated in response to the microactuator position signal.

Assignees

• Seagate Technology Llc
• Segate Tech Llc

Inventors

• Park Sung Won
• Seo Sangbo

Classifications

• G11B5/556 Primary

  control circuits therefor · CPC title

• G11B5/59694 Primary

  System adaptation for working during or after external perturbation, e.g. in the presence of a mechanical oscillation caused by a shock · CPC title

• G11B5/59627 Primary

  Aligning for runout, eccentricity or offset compensation (G11B5/5534, G11B5/59677, G11B5/59688 take precedence) · CPC title