Positional indicia misplacement compensation

• US 20070096678A1
• Filed: 11/03/2006
• Published: 05/03/2007
• Est. Priority Date: 11/03/2005
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Melrose, Thomas
• Granted Patent: US 7,782,003 B2
• Time in Patent Office: Days
• US Class Current: 318/652
• CPC Class Codes: G05B 19/251 the positional error is used to control continuously the servomotor according to its magnitude
• CPC Class Codes: G05B 2219/41203 Lead-phase compensation, lag-phase compensation servo
• CPC Class Codes: G05B 2219/41207 Lookup table with position command, deviation and correction value

Abstract

Apparatus and method for compensating for positional indicia misplacements in the positioning of a control object, such as with servo seam misplacements on a data storage device storage medium. An actual position for the control object is determined in relation to a corrected commanded position of the control object and a corrected position error of the control object. The corrected commanded position is determined in relation to a gain error and an actual commanded position, and the corrected position error determined in relation to the gain error and an actual position error. Preferably, an actual position error of the control object is next determined in relation to the actual position, and the control object is moved to reduce the actual position error. The positional indicia preferably comprise AB and CD seams of ABCD servo dibit patterns on a recording surface.

Claims

1. A method comprising determining an actual position of a control object in relation to a corrected commanded position of the control object and a corrected position error of the control object, the corrected commanded position determined in relation to a gain error and an actual commanded position, and the corrected position error determined in relation to said gain error and an actual position error.

2. The method of claim 1, further comprising a step of generating an actual position error of the control object in relation to the actual position and the actual commanded position of the determining step.

3. The method of claim 2, further comprising a step of moving the control object in relation to the actual position error of the generating step.

4. The method of claim 1, wherein the corrected commanded position is further determined in relation to an embedded runout compensation value indicative of a positional error distance between an ideally located positional indicia and an actual location of positional indicia.

5. The method of claim 4, wherein the gain error is determined in relation to said embedded runout compensation value.

6. The method of claim 4, wherein the positional indicia comprise servo dibit patterns on a storage medium.

7. The method of claim 6, wherein the positional indicia comprises a servo seam at the boundary between adjacent servo dibit patterns.

8. The method of claim 1, wherein the gain error of the determining step is determined in relation to at least one embedded runout correction value indicative of positional error distance between an ideally located positional indicia and an actual location of positional indicia.

9. The method of claim 1, wherein the control object comprises a transducer of a data storage device, and the actual position comprises an actual position of the transducer with respect to an associated data storage surface adjacent the transducer.

10. An apparatus comprising:

a control object; and

a servo circuit configured to position the control object in response to a received commanded position therefor, the servo controller determining an actual position of the control object in relation to a corrected commanded position of the control object and a corrected position error of the control object, wherein the servo circuit determines the corrected commanded position in relation to a gain error and said received commanded position, and wherein the servo circuit determines the corrected position error in relation to said gain error and an actual position error.

11. The apparatus of claim 10, wherein the servo circuit further operates to generate an actual position error of the control object in relation to the actual position and the received commanded position.

12. The apparatus of claim 11, wherein the servo circuit further moves the control object to reduce said actual position error.

13. The apparatus of claim 11, wherein the servo circuit further operates to generate the gain error in relation to at least one embedded runout correction value indicative of positional error distance between ideally located positional indicia and an actual location of said positional indicia.

14. The apparatus of claim 13, characterized as a data storage device and wherein the positional indicia comprise servo dibit patterns on a storage medium of the device.

15. The apparatus of claim 14, wherein the positional indicia comprises a servo seam at the boundary between adjacent servo dibit patterns.

16. The apparatus of claim 10, wherein the control object comprises a transducer of a data storage device, and the actual position comprises an actual position of the transducer with respect to an associated data storage surface adjacent the transducer.

17. The apparatus of claim 10, wherein the servo circuit comprises a programmable processor with an associated programming routine used to determine the actual position of the control object.

18. An apparatus comprising a control object, and first means for determining an actual position of the control object.

19. The apparatus of claim 18, wherein the first means comprises a servo circuit configured to position the control object in response to a received commanded position therefor, the servo controller determining the actual position of the control object in relation to a corrected commanded position of the control object and a corrected position error of the control object, wherein the servo circuit determines the corrected commanded position in relation to a gain error and said received commanded position, and wherein the servo circuit determines the corrected position error in relation to said gain error and an actual position error.

20. The apparatus of claim 18, wherein the control object is characterized as a transducer of a data storage device.