Dual-calibrated compass

• US 6,192,315 B1
• Filed: 06/27/1997
• Issued: 02/20/2001
• Est. Priority Date: 06/27/1997
• Status: Expired due to Term

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Prince (Wellman Holdings, Inc.)
• Inventors: Michmerhuizen, Mark, Geschke, James R., Colon, Gregory B., Olson, Thomas R.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): DONNELLY, ARTHUR D
• Application Number:
  US08/884,454
• Time in Patent Office: 1,334 Days
• Field of Search: 701/224, 701/211, 701/220, 701/207, 701/200, 702/85, 702/92, 702/93, 702/150, 73/17.5, 73/17.6, 333/24, 333/55.R, 333/56
• US Class Current: 701/224
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

An electronic compass system of the present invention includes a sensor for detecting the earth'"'"'s magnetic field and for providing electrical signals representing the direction of the vehicle, a heading indicator for indicating vehicle headings in response to received vehicle heading signals, and a processor coupled to the sensor for receiving the electrical signals and coupled to the heading indicator for supplying the vehicle heading signals to the heading indicator. The processor preferably includes a first compass controller for calculating vehicle headings in response to the received electrical signals using precalibration data to compensate for expected vehicular magnetism, a second compass controller for calculating vehicle headings in response to the received electrical signals using an automatic calibration routine to compensate for actual vehicular magnetism, and a control transferring mechanism for initially selecting the vehicle headings calculated by the first compass controller to be represented by the vehicle heading signal supplied to the heading indicator, and for selecting the vehicle headings calculated by the second compass controller after the automatic calibration routine has acquired sufficient data from the magnetic field sensor to calibrate the compass system. The heading indicator may include a display and/or an audio messaging device for generating audible vehicle heading messages. If such an audible messaging device is employed, the device may also be used to record and playback dictated memos.

Claims

1. An electronic compass system for a vehicle comprising:

a magnetic field sensor for detecting the earth'"'"'s magnetic field and for providing electrical signals representing the direction of the vehicle in relation to the earth'"'"'s magnetic field;

a heading indicator for indicating vehicle headings in response to received vehicle heading signals; and

a processor coupled to said magnetic field sensor for receiving said electrical signals and coupled to said heading indicator for supplying the vehicle heading signals to said heading indicator, said processor including

first compass control means for calculating vehicle headings in response to said received electrical signals using precalibration data to compensate for expected vehicular magnetism,

second compass control means for calculating vehicle headings in response to said received electrical signals using an automatic calibration routine to compensate for actual vehicular magnetism, and

control transfer means for initially selecting the vehicle headings calculated by said first compass control means to be represented by the vehicle heading signal supplied to said heading indicator, and for selecting the vehicle headings calculated by said second compass control means after the automatic calibration routine has acquired sufficient data from said magnetic field sensor to calibrate the compass system.

2. The compass system as defined in claim 1, wherein said control transfer means selects the vehicle headings calculated by said second compass control means when a vehicle heading calculated by said first compass control means is the same as a vehicle heading calculated by said second compass control means.

3. The compass system as defined in claim 1, wherein the automatic calibration routine is determined to have acquired sufficient data from said magnetic field sensor to calibrate the compass system when data is acquired from the sensor during travel of the vehicle through at least one 360 degree loop.

4. The compass system as defined in claim 1, wherein the automatic calibration routine is determined to have acquired sufficient data from said magnetic field sensor to calibrate the compass system when data is acquired from the sensor during travel of the vehicle through three 360 degree loops.

5. The compass system as defined in claim 1, wherein said heading indicator includes a display for displaying the vehicle'"'"'s heading in response to the received vehicle heading signals.

6. The compass system as defined in claim 1, wherein said heading indicator includes audio messaging means for selecting for playback one of a plurality of prestored audio messages stating a heading corresponding to the vehicle heading identified in the received vehicle heading signal.

7. The compass system as defined in claim 6, wherein said audio messaging means includes:

memory means for storing a plurality of prestored audio messages each corresponding to a different potential vehicle heading;

message selecting means included in said processor and coupled to said memory means for selecting for playback one of said plurality of prestored audio messages that corresponds to the vehicle heading represented by the vehicle heading signal; and

audio output means coupled to said message selecting means for audibly generating the selected prestored audio message.

8. A method for calibrating a vehicle compass system to account for changes in vehicular magnetism, the vehicle compass system having a magnetic field sensor for providing electrical signals representing the earth'"'"'s magnetic field, a processing circuit for processing said electrical signals to generate vehicle heading signals representing the vehicle'"'"'s heading, and a heading indicator indicating the vehicle'"'"'s heading in response to the vehicle heading signals received from the processing circuit, said method comprising the steps of:

(a) calculating a vehicle heading in response to the electrical signals output from the magnetic field sensor using precalibration data to compensate for expected vehicular magnetism;

(b) generating and supplying a vehicle heading signal representing the vehicle heading calculated in step (a) to the heading indicator;

(c) executing an automatic calibration routine to calculate compensation data to correct for actual vehicular magnetism and to calculate a vehicle heading in response to said received electrical signals using the compensation data;

(d) determining whether the automatic calibration routine has acquired sufficient data from said magnetic field sensor to calibrate the compass system;

(e) repeating steps (a) through (d) until it has been determined in step (d) that the automatic calibration routine has acquired sufficient data; and

(f) generating and supplying vehicle heading signals to the heading indicator representing vehicle headings calculated in response to said received electrical signals using the compensation data generated by the automatic calibration routine.

9. The method as defined in claim 8, wherein the automatic calibration routine is determined to have acquired sufficient data from the magnetic field sensor to calibrate the compass system in step (d) when data is acquired from the sensor during travel of the vehicle through at least one 360 degree loop.

10. The method as defined in claim 8, wherein the automatic calibration routine is determined to have acquired sufficient data from said magnetic field sensor to calibrate the compass system in step (d) when data is acquired from the sensor during travel of the vehicle through three 360 degree loops.

11. A method for calibrating a vehicle compass system to account for changes in vehicular magnetism, the vehicle compass system having a magnetic field sensor for providing electrical signals representing the earth'"'"'s magnetic field, a processing circuit for processing said electrical signals to generate vehicle heading signals representing the vehicle'"'"'s heading, and a heading indicator indicating the vehicle'"'"'s heading in response to the vehicle heading signals received from the processing circuit, said method comprising the steps of:

(a) calculating a vehicle heading in response to the electrical signals output from the magnetic field sensor using precalibration data to compensate for expected vehicular magnetism;

(b) generating and supplying a vehicle heading signal representing the vehicle heading calculated in step (a) to the heading indictor;

(c) executing an automatic calibration routine to calculate compensation data to correct for actual vehicular magnetism and to calculate a vehicle heading in response to said received electrical signals using the compensation data;

(d) determining whether the automatic calibration routine has acquired sufficient data from said magnetic field sensor to calibrate the compass system;

(e) determining whether the vehicle heading calculated in step (a) is the same as the vehicle heading calculated in step (c);

(f) repeating steps (a) through (e) until (1) it has been determined in step (d) that the automatic calibration routine has acquired sufficient data and (2) it has been determined in step (e) that the vehicle heading calculated in step (a) is the same as the vehicle heading calculated in step (c); and

(g) generating and supplying vehicle heading signals to the heading indicator representing vehicle headings calculated in response to said received electrical signals using the compensation data generated by the automatic calibration routine.

12. An electronic compass system for a vehicle comprising:

a magnetic field sensor for detecting the earth'"'"'s magnetic field and for providing electrical signals representing the direction of the vehicle in relation to the earth'"'"'s magnetic field;

a heading indicator for indicating vehicle headings in response to received vehicle heading signals; and

a processor coupled to said magnetic field sensor for receiving said electrical signals and coupled to said heading indicator for supplying the vehicle heading signals to said heading indicator, said processor including

first compass control means for calculating vehicle headings in response to said received electrical signals using precalibration data to compensate for expected vehicular magnetism,

second compass control means for calculating vehicle headings in response to said received electrical signals using an automatic calibration routine to compensate for actual vehicular magnetism, and

control transfer means for initially selecting the vehicle headings calculated by said first compass control means to be represented by the vehicle heading signals supplied to said heading indicator, and for selecting the vehicle headings calculated by said second compass control means when a vehicle heading calculated by said first compass control means is the same as a vehicle heading calculated by said second compass control means.

13. An electronic compass system for a vehicle comprising:

a magnetic field sensor for detecting the earth'"'"'s magnetic field and for providing electrical signals representing the direction of the vehicle in relation to the earth'"'"'s magnetic field;

a memory for storing a plurality of prestored audio messages each corresponding to a different vehicle heading;

a processor coupled to said magnetic field sensor for receiving said electrical signals and calculating a vehicle heading in response to said electrical signals, said processor further being coupled to said memory for selecting for playback one of said plurality of prestored audio messages that corresponds to the calculated vehicle heading;

a first compass control means for calculating vehicle headings in response to said electrical signals using precalibration data to compensate for expected vehicular magnetism,

a second compass control means for calculating vehicle headings in response to said electrical signals using an automatic calibration routine to compensate for actual vehicular magnetism; and

a control transfer means for initially selecting the vehicle headings calculated by said first compass control means to be represented by the vehicle heading signal supplied to said heading indicator, and for selecting the vehicle headings calculated by said second compass control means after the automatic calibration routine has acquired sufficient data from said magnetic field sensor to calibrate the compass system; and

an audio transducer coupled to said processor and said memory means for audibly generating the selected prestored audio message.

14. The compass system as defined in claim 13, wherein said transducer is a speaker.

15. The compass system as defined in claim 13, wherein said audio messages include “

north,”

“

south,”

“

east,” and

“

west.”

16. The compass system as defined in claim 15, wherein said audio messages include “

Northeast,”

“

Southeast,”

“

Southwest,” and

“

Northwest.”

17. The compass system as defined in claim 13, wherein said processor further includes:

first compass control means for calculating vehicle headings in response to said received electrical signals using precalibration data to compensate for expected vehicular magnetism;

second compass control means for calculating vehicle headings in response to said received electrical signals using an automatic calibration routine to compensate for actual vehicular magnetism; and

control transfer means for initially selecting the vehicle headings calculated by said first compass control means for use in selecting for playback one of said prestored audio messages, and for selecting the vehicle headings calculated by said second compass control means when a vehicle heading calculated by said first compass control means is the same as a vehicle heading calculated by said second compass control means.

18. The compass system as defined in claim 13, wherein said processor further includes:

first compass control means for calculating vehicle headings in response to said received electrical signals using precalibration data to compensate for expected vehicular magnetism;

second compass control means for calculating vehicle headings in response to said received electrical signals using an automatic calibration routine to compensate for actual vehicular magnetism; and

control transfer means for initially selecting the vehicle headings calculated by said first compass control means for use in selecting for playback one of said prestored audio messages, and for selecting the vehicle headings calculated by said second compass control means after the automatic calibration routine has acquired sufficient data from said magnetic field sensor to calibrate the compass system.

19. The compass system as defined in claim 13 and further including a user interface coupled to said processor for receiving user commands, and audio input means coupled to said processor for receiving voice information, wherein said processor responds to a record command received from said user interface by enabling said audio input means to digitize received voice information and recording the digitized voice information in said memory.

20. The compass system as defined in claim 19, wherein said processor responds to a playback command received from said user interface by reading recorded voice information from said memory and by enabling said transducer to audible the recorded voice information.

21. The compass system as defined in claim 20, wherein said user interface includes a first user-actuated switch for inputting a record command and a second user-actuated switch for inputting a playback command.

22. The compass system as defined in claim 13 and further including a user interface coupled to said processor for receiving user commands, wherein said processor responds to a user command to output the vehicle heading by selecting and reading from said memory the prestored audio message corresponding to the calculated vehicle heading and by enabling said transducer to audible the selected audio message.

23. The compass system as defined in claim 22, wherein said user interface includes a user-actuated switch for inputting a command to output the vehicle heading.

24. An accessory for a vehicle comprising:

a housing;

an electronic compass field for providing electrical signals representing the direction of the vehicle in relation to the earth'"'"'s magetic field, provided in said housing for indicating the vehicle'"'"'s heading;

an audio input means provided in said housing for receiving an audible message;

a memory coupled to said audio input means for storing audio messages;

a transducer provided in said housing and coupled to said memory for audibly generating a selected audio message;

a user interface provided in said housing for receiving user commands; and

a processor coupled to said user interface, said transducer, said audio input means, and said memory, wherein said processor responds to a record command received from said user interface by enabling said audio input means to digitize a received audible message and by recording the digitized message in said memory, and said processor responds to a playback command received from said user interface by selecting and reading a recorded audio message from said memory and by enabling said transducer to audiblize the recorded audio message; and

a first compass control means for calculating vehicle headings in response to said electrical signals using precalibration data to compensate for expected vehicular magnetism

a second compass control means for calculating vehicle headings in response to said electrical signals using an automatic calibration routine to compensate for actual vehicular magnetism; and

a control transfer means for initially selecting the vehicle headings calculated by said first compass control means to be represented by the vehicle heading signal supplied to said heading indicator, and for selecting the vehicle headings calculated by said second compass control means after the automatic calibration routine has acquired sufficient data from said magnetic field.

25. The vehicle accessory as defined in claim 24, wherein said electronic compass includes a sensor coupled to said processor for supplying electric signals representing the earth'"'"'s magnetic field, said processor calculates the vehicle'"'"'s heading from the electric signals from said sensor.

26. The vehicle accessory as defined in claim 25, wherein a plurality of prestored audio messages are stored in said memory that each correspond to a different vehicle heading, and said processor selects for playback through said transducer a prestored audio message that corresponds to the vehicle'"'"'s calculated heading.