System and method for compensating for magnetic disturbance of a compass by a moveable vehicle accessory

• US 20070101596A1
• Filed: 04/30/2004
• Published: 05/10/2007
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Wright, Thomas, Olson, Thomas, Natus, Sven
• Granted Patent: US 7,346,995 B2
• Time in Patent Office: Days
• US Class Current: 33/356
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

A vehicle compass system for compensating for magnetic disturbances caused by a moveable vehicle accessory includes a magnetic field sensor and a control circuit coupled to the moveable vehicle accessory and the magnetic field sensor. The magnetic field sensor is positioned at a distance from the moveable vehicle accessory and is configured to determine an orientation of the magnetic field sensor with respect to the Earth'"'"'s magnetic field and to generate magnetic field data. The control circuit is configured to receive a position signal from the moveable vehicle accessory indicating whether the moveable vehicle accessory is changing position, to receive magnetic field data from the magnetic field sensor, to compare first magnetic field data generated prior to the change in position of the moveable vehicle accessory to second magnetic field data generated after the change in position of the moveable vehicle accessory and to generate a correction value based on the comparison of the first magnetic field data and the second magnetic field data. The correction value is used to correct for the magnetic disturbance caused by the moveable vehicle accessory.

Claims

1. A vehicle compass system for compensating for magnetic disturbances caused by a moveable vehicle accessory, the vehicle compass system comprising:

a magnetic field sensor configured to determine an orientation of the magnetic field sensor with respect to the Earth'"'"'s magnetic field and to generate magnetic field data, the magnetic field sensor positioned at a distance from the moveable vehicle accessory; and

a control circuit coupled to the moveable vehicle accessory and the magnetic field sensor, the control circuit configured to receive a position signal from the moveable vehicle accessory indicating whether the moveable vehicle accessory is changing position, to receive magnetic field data from the magnetic field sensor, to compare first magnetic field data generated prior to the change in position of the moveable vehicle accessory to second magnetic field data generated after the change in position of the moveable vehicle accessory and to generate a correction value based on the comparison of the first magnetic field data and the second magnetic field data;

wherein the correction value is used to correct for the magnetic disturbance caused by the moveable vehicle accessory.

2. A vehicle compass system according to claim 1, wherein the correction value is used to update at least one calibration value.

3. A vehicle compass system according to claim 1, wherein the correction value is used to correct third magnetic field data generated after the change in position of the moveable vehicle accessory.

4. A vehicle compass system according to claim 1, wherein the magnetic field sensor further comprises:

a first magnetic field sensor configured to measure magnetic field data with respect to a first magnetic axis;

a second magnetic field sensor configured to measure magnetic field data with respect to a second magnetic axis orthogonal to the first magnetic axis.

5. A vehicle compass system according to claim 1, wherein the control circuit is coupled to a control switch of the moveable vehicle accessory, the control switch configured to generate the position signal.

6. A vehicle compass system according to claim 1, wherein he control circuit is coupled to a position sensor of the moveable vehicle accessory, the position sensor configured to determine whether the moveable vehicle accessory is changing position and to generate the position signal.

7. A vehicle compass system according to claim 6, wherein the position sensor is further configured to determine a position of the moveable vehicle accessory and the position signal is further configured to indicate the position of the moveable vehicle accessory.

8. A vehicle compass system according to claim 1, wherein the moveable vehicle accessory is a sunroof.

9. A vehicle compass system according to claim 1, wherein the control circuit is configured to detect a change in position of the moveable vehicle accessory which occurs while the vehicle compass system is powered down.

10. A vehicle compass system according to claim 1, further comprising:

a steering wheel sensor coupled to the control circuit and configured to provide a direction status signal indicating whether the vehicle is changing direction; and

a speed sensor coupled to the control circuit and configured to provide a speed signal indicating the speed of the vehicle;

wherein the control circuit is further configured to determine a magnetic disturbance caused by the changing of direction of the vehicle based on the direction status signal and the speed signal.

11. A vehicle compass system according to claim 10, wherein, in response to a direction status signal indicating the vehicle is changing direction, the control circuit is configured to compare the correction value to a stored magnetic shift value for the moveable vehicle accessory and to determine a magnetic disturbance caused by the change in position of the moveable vehicle accessory and a magnetic disturbance caused by the change of direction of the vehicle.

12. A method for compensating for magnetic disturbances of a compass caused by a moveable vehicle accessory positioned a distance from a magnetic field sensor of the compass, the method comprising:

determining if the moveable vehicle accessory is changing position;

determining first magnetic field data prior to the change in position of the moveable vehicle accessory;

determining second magnetic field data after the change in position of the moveable vehicle accessory;

comparing the first magnetic field data and the second magnetic field data;

generating a correction value based on the comparison of the first magnetic field data and the second magnetic field data; and

updating at least one calibration value of the compass based on the correction value.

13. A method according to claim 12, wherein the moveable vehicle accessory is a sunroof.

14. A method according to claim 12, wherein determining if the moveable vehicle accessory is changing position includes receiving a position signal generated by a control switch of the moveable vehicle accessory.

15. A method according to claim 14, wherein the position signal indicates whether the moveable vehicle accessory is changing position.

16. A method according to claim 12, wherein determining if the moveable vehicle accessory is changing position includes receiving a position signal generated by a position sensor of the moveable vehicle accessory.

17. A method according to claim 16, wherein the position sensor is configured to determine the position of the moveable vehicle accessory.

18. A method according to claim 12, further comprising:

receiving a direction status signal indicating whether the vehicle is changing direction;

receiving a speed signal indicating the speed of the vehicle; and

determining a magnetic disturbance caused by the changing of direction of the vehicle based on the direction status signal and the speed signal.

19. A method according to claim 18, further comprising:

comparing the correction value to a stored magnetic shift value for the moveable vehicle accessory; and

determining a magnetic disturbance caused by the change in position of the moveable vehicle accessory and a magnetic disturbance caused by the change in direction of the vehicle.

20. A method for compensating for magnetic disturbances of a compass caused by a moveable vehicle accessory positioned a distance from a magnetic field sensor of the compass, the method comprising:

determining if the moveable vehicle accessory is changing position;

determining first magnetic field data prior to the change in position of the moveable vehicle accessory;

determining second magnetic field data after the change in position of the moveable vehicle accessory;

comparing the first magnetic field data and the second magnetic field data;

generating a correction value based on the comparison of the first magnetic field data and the second magnetic field data; and

correcting third magnetic field data determined after the change in position of the moveable vehicle accessory based on the correction value.

21. A method for compensating for magnetic disturbances of a compass caused by a moveable vehicle accessory, the method comprising:

receiving magnetic field data from a magnetic field sensor positioned a distance from the moveable vehicle accessory;

recording the data from the magnetic field sensor;

receiving a first position signal indicating the moveable vehicle accessory has begun changing position;

halting storage of the magnetic field data from the magnetic field sensor based on the first position signal;

receiving a second position signal indicating the moveable vehicle accessory has ceased changing position;

recommencing storing the magnetic field data from the magnetic field sensor based on the second position signal; and

determining a correction value based on the magnetic field data stored before receipt of the first position signal and the magnetic field data stored after receipt of the second position signal.

22. A method according to claim 21, wherein the moveable vehicle accessory is a sunroof.

23. A method according to claim 21, wherein the correction value is used to update at least one calibration value of the vehicle compass system.

24. A method according to claim 21, wherein the correction value is used to correct magnetic field data received after receipt of the second position signal.