System using magnetic signatures to detect a vehicle event

• US 6,286,221 B1
• Filed: 01/13/2000
• Issued: 09/11/2001
• Est. Priority Date: 01/13/2000
• Status: Expired due to Term

• Current Assignee: Aptiv Technologies Limited (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Voto, Andrew Michael, Selby, Ronald Kenneth, Dantzler, Maurice Lydell, Glomski, Paul Thaddeus
• Primary Examiner(s): Fulton, Christopher W.
• Application Number:
  US09/482,043
• Time in Patent Office: 607 Days
• Field of Search: 333/56, 336/00, 333/55.R, 333/57, 702/92, 702/93
• US Class Current: 33/356
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

An electronic compass system using magnetic signatures to detect a vehicle event which is integrated with an instrument cluster. A vehicle accessory, such as a rear defrost grid, generates a known, consistent, magnetic field of intensity sufficient to cause a static magnetic offset in the electronic compass for each of its'"'"' electrical states. This known consistent, magnetic field has a magnetic signature. A magnetic field sensor detects a combination of Earth'"'"'s magnetic field and the stray magnetic field produced by the vehicle accessory. A controller is coupled to the magnetic field sensor and searches the magnetic field signal for the magnetic signature. The controller then looks up a predetermined correction factor, or uses an algorithm to determine a correction factor, corresponding to the magnetic signature, to eliminate the effect of the static magnetic offset. The controller then displays a heading unaffected by the static magnetic offset.

Claims

1. An electronic compass system using magnetic signatures to detect a vehicle event comprising:

a vehicle accessory having at least one electrical state, said vehicle accessory generating a known, consistent, magnetic field of an intensity sufficient to cause a static magnetic offset in said electronic compass, said known, consistent, magnetic field having a magnetic signature;

a magnetic field sensor located in proximity to said vehicle accessory, said magnetic field sensor detecting a combination of Earth'"'"'s magnetic field and said known, consistent, magnetic field and generating a magnetic field signal wherein said Earth'"'"'s magnetic field is modified by said static magnetic offset;

a controller coupled to said magnetic field sensor and receiving said magnetic field signal, said controller having control logic operative to search said magnetic field signal for said magnetic signature, lookup a correction factor for said magnetic signature stored in a memory location, and apply said correction factor to said magnetic field signal; and

a display coupled to said controller, said display displaying a heading unaffected by said static magnetic offset.

2. The electronic compass system using magnetic signatures to detect a vehicle event as recited in claim 1, wherein said electronic compass is integrated in an instrument cluster.

3. The electronic compass system using magnetic signatures to detect a vehicle event as recited in claim 1, wherein said vehicle accessory is located in an instrument panel.

4. The electronic compass system using magnetic signatures to detect a vehicle event as recited in claim 1, wherein said vehicle accessory is one selected from the group comprising:

headlamps, tail lamps, stop lamps, a wiper motor, or a rear defrost grid.

5. The electronic compass system using magnetic signatures to detect a vehicle event as recited in claim 1, wherein the proximity of said magnetic sensor to said vehicle accessory is optimized to minimize said static magnetic offset.

6. The electronic compass system using magnetic signatures to detect a vehicle event as reciting in claim 1, wherein said static magnetic offset varies due to variation in said vehicle accessory and temperature.

7. The electronic compass system using magnetic signatures to detect a vehicle event as reciting in claim 6, wherein said controller includes control logic operative to determine a maximum positive magnetic offset of said vehicle accessory, determine a maximum negative magnetic offset of said vehicle accessory, and scale said compensation factor based upon said maximum positive and negative magnetic offsets.

8. A method for using information on a communications bus to eliminate magnetic noise in an electronic compass comprising the steps of:

generating a known, consistent, magnetic field of an intensity sufficient to cause a static magnetic offset in said electronic compass, said known, consistent magnetic field having a magnetic signature corresponding to at least one electrical state of a vehicle accessory;

detecting a combination of Earth'"'"'s magnetic field and said known, consistent, magnetic field wherein said Earth'"'"'s magnetic field is modified by said static magnetic offset to generate an magnetic field signal;

receiving a magnetic field signal corresponding to said electrical state;

searching said magnetic field signal for said magnetic signature;

looking up a predetermined correction factor for said magnetic signature stored in a memory location;

applying said predetermined compensation factor, corresponding to said magnetic signature, to said magnetic field signal; and

displaying a heading unaffected by said static magnetic offset.

9. The method for using information on a communications bus to eliminate magnetic noise in an electronic compass as recited in claim 8, wherein the step of generating comprises generating a known, consistent, magnetic field of an intensity sufficient to cause a static magnetic offset in said electronic compass, said known, consistent magnetic field corresponding to at least one electrical state of a vehicle accessory, said known, consistent magnetic field varying due to variation in said vehicle accessory and temperature.

10. The method for using information on a communications bus to eliminate magnetic noise in an electronic compass as recited in claim 9, further comprising the steps of:

determining a maximum positive magnetic offset of said vehicle accessory;

determining a maximum negative magnetic offset of said vehicle accessory; and

scaling said compensation factor based upon said maximum and minimum magnetic offsets.

11. An electronic compass system using magnetic signatures to detect a vehicle event comprising:

a vehicle having an instrument panel

an instrument cluster located in said instrument panel;

a vehicle accessory having at least one electrical state and generating a corresponding known, consistent, magnetic field of an intensity sufficient to cause a static magnetic offset in said electronic compass, said known, consistent, magnetic field having a magnetic signature;

a magnetic field sensor located in said instrument cluster and in proximity to said vehicle accessory, said magnetic field sensor detecting a combination of Earth'"'"'s magnetic field and said known, consistent, magnetic field and generating a magnetic field signal wherein said Earth'"'"'s magnetic field is modified by said static magnetic offset;

a controller located in said instrument cluster and coupled to said magnetic field sensor and receiving said magnetic field signal, said controller having control logic operative to search said magnetic field signal for said magnetic signature, lookup a correction factor for said magnetic signature stored in a memory location, and apply said correction factor for said magnetic field signal; and

a display located in said instrument cluster and coupled to said controller, said display displaying a heading unaffected by said static magnetic offset.

12. The electronic compass system using magnetic signatures to detect a vehicle event as recited in claim 11, wherein said vehicle accessory is one selected from the group comprising:

headlamps, tail lamps, stop lamps, a wiper motor, or a rear defrost grid.

13. The electronic compass system using magnetic signatures to detect a vehicle event as recited in claim 11, wherein the proximity of said magnetic sensor to said vehicle accessory is optimized to minimize said static magnetic offset.

14. The electronic compass system using magnetic signatures to detect a vehicle event as reciting in claim 11, wherein said static magnetic offset varies due to variation in said vehicle accessory and temperature.

15. The electronic compass system using magnetic signatures to detect a vehicle event as reciting in claim 14, wherein said controller includes control logic operative to determine a maximum positive magnetic offset of said vehicle accessory, determine a maximum negative magnetic offset of said vehicle accessory, and scale said compensation factor based upon said maximum positive and negative magnetic offsets.