Electronic compass and method of controlling an electronic compass using independent calibration and compass heading modules

• US 20050228603A1
• Filed: 04/07/2005
• Published: 10/13/2005
• Est. Priority Date: 04/07/2004
• Status: Active Grant

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Inventors: Bernard, Francois-Xavier, Fillatreau, Philippe
• Granted Patent: US 7,248,983 B2
• Time in Patent Office: Days
• US Class Current: 702/92
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

A method for controlling an electronic compass includes receiving raw magnetic field data into a calibration module and determining a calibration output based upon the raw magnetic field data. The raw magnetic field data is also received into a compass heading module for determining compass heading outputs based upon the raw magnetic field data. The calibration module filters the raw magnetic field data and validates the calibration outputs independently from output data filtering and results validation in the compass heading module.

Claims

1. A method of controlling an electronic compass comprising:

receiving raw magnetic field data into a calibration module;

determining a calibration output based upon the raw magnetic field data;

receiving the raw magnetic field data into a compass heading module; and

determining compass heading outputs based upon the raw magnetic field data.

2. The method as recited in claim 1, including selectively filtering the raw magnetic field data within the calibration module to produce first filtered data, and determining the calibration output based upon the first filtered data.

3. The method as recited in claim 2, including selectively filtering the raw magnetic field data within the compass heading module to produce second filtered data, and determining the compass heading output based upon the second filtered data.

4. The method as recited in claim 3, including producing at least one overlapping magnetic field data point and at least one different magnetic field data point in the first filtered data and the second filtered data.

5. The method as recited in claim 3, including comparing the raw magnetic field data to a first noise threshold to produce the first filtered data and comparing the raw magnetic field data to a different, second noise threshold to produce the second filtered data.

6. The method as recited in claim 5, including accepting a data point of the raw magnetic field data for inclusion in the first filtered data or the second filtered data and rejecting the data point for inclusion in the other of the first filtered data or second filtered data.

7. The method as recited in claim 3, including smoothing a data point of the raw magnetic field data according to a first smoothing parameter for inclusion in the first filtered data or the second filtered data and smoothing the data point according to a different, second smoothing parameter for inclusion in the other of the first filtered data or second filtered data.

8. The method as recited in claim 3, including rejecting one of the calibration output or the compass heading output and accepting the other of the calibration output or the compass heading output.

9. The method as recited in claim 3, including selectively filtering the raw magnetic field data to produce first filtered data before receiving the raw magnetic field data into the second filter module.

10. An electronic compass assembly comprising:

a calibration module operable to receive raw magnetic field data and determine a calibration output based upon the raw magnetic field data; and

a compass heading module operable to receive the raw magnetic field data and determine compass heading outputs based upon the raw magnetic field data.

11. The assembly as recited in claim 10, wherein the calibration module includes a first filter module that is operable to receive raw magnetic field data, produce first filtered data based upon the raw magnetic field data, and determine the calibration output based upon the first filtered data.

12. The assembly as recited in claim 11, wherein the compass heading module includes a second filter module that is operable to receive the raw magnetic field data, produce second filtered data based upon the raw magnetic field data, and determine the compass heading outputs based upon the second filtered data.

13. The assembly as recited in claim 12, wherein the first filtered data and the second filtered data each include at least one overlapping magnetic field data point and at least one different magnetic field data point.

14. The assembly as recited in claim 12, wherein the first filter module is operable to produce the first filtered data based upon a first noise threshold and the second filter module is operable to produce the second filtered data based upon a different, second noise threshold.

15. The assembly as recited in claim 14, wherein one of the first filter module or the second filter module rejects a portion of the raw magnetic field data for inclusion, respectively, in the first filtered data or the second filtered data, and the other of the first filter module or the second filter module accepts the portion of the raw magnetic field data for inclusion, respectively, in the first filtered data or the second filtered data.

16. The assembly as recited in claim 12, wherein at least one of the first filter module or the second filter module is operable to smooth a portion of the raw magnetic field data to respectively produce the first filtered data or the second filtered data.

17. The assembly as recited in claim 10, wherein the calibration module is operable to selectively reject the calibration output and the compass heading module is operable to selectively reject the compass heading output.

18. The assembly as recited in claim 10, including at least one magnetic field sensor that senses a magnetic field and produces output signals corresponding to the raw magnetic field data.

19. The assembly as recited in claim 10, including a display portion in communication with the compass heading module for displaying vehicle directions based upon the compass heading outputs.