Intelligent ultra high speed distributed sensing system and method for sensing roadway markers for intelligent vehicle guidance and control

• US 20030046021A1
• Filed: 01/08/2002
• Published: 03/06/2003
• Est. Priority Date: 05/31/2001
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Yen, Kin S., Ravani, Bahram, Donecker, Stephen M., Lasky, Ty A.
• Granted Patent: US 6,772,062 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: E01F 9/30 Arrangements interacting with transmitters or receivers otherwise than by visible means, e.g. using radar reflectors or radio transmitters E01F11/00 takes precedence
• CPC Class Codes: G05D 1/0261 using magnetic plots

Abstract

Methods and apparatus to sense both discrete and continuous magnetic reference systems installed in the roadway, and provide information to support lateral and, to some extent, longitudinal and vertical vehicle control and/or driver assistance. The position of an object, such as a vehicle, relative to a magnetic reference infrastructure, such as that representing a dividing line on a roadway, is determined by sensing, with a sensor associated with the object, at least one axial field strength component of the magnetic field emitted from the magnetic reference, computing a ratio of the sensed axial field strength components, and then determining the positional offset of the object as a function of the ratio. The lateral offset is independent of the magnetic field strength due to the use of the ratio which cancels out the magnetic field strength. The invention is also capable of providing three-dimensional positioning relative to a magnetic reference.

Claims

1. A method for determining the position of an object relative to a magnetic reference marker, comprising:

sensing, with a sensor associated with an object, at least one axial field strength component of the magnetic field emitted from a magnetic reference;

computing a ratio of said sensed axial field strength components; and

determining a positional offset of said object from said magnetic reference as a function of said ratio.

2. A method as recited in claim 1, wherein said ratio is dimensionless.

3. A method as recited in claim 1, wherein said positional offset is independent of magnetic reference field strength.

4. A method as recited in claim 1, further comprising domain mapping said ratio to said positional offset.

5. A method as recited in claim 1:

wherein said magnetic reference comprises a magnetic infrastructure defining a roadway reference line; and

wherein said positional offset comprises lateral offset in relation to said roadway reference line.

6. A method as recited in claim 1, wherein said sensor comprises a digital magnetometer.

7. A method as recited in claim 6, wherein said magnetometer comprises a multiple-axis magnetometer.

8. A method as recited in claim 6, wherein each said magnetometer provides magnetic field strength readings in digital form for all available axes.

9. A method as recited in claim 8, wherein said magnetometer communicates said field strength readings to a digital data processor.

10. A method as recited in claim 9, wherein said digital data processor processes said field strength readings to obtain said positional offset.

11. A method for determining the position of an object relative to a magnetic reference, comprising:

sensing, with each of at least two sensors associated with an object, at least one axial field strength component of the magnetic field emitted from a magnetic reference;

computing a ratio of said sensed axial field strength components; and

determining a positional offset of said object from said magnetic reference as a function of said ratio.

12. A method as recited in claim 11, wherein said ratio is dimensionless.

13. A method as recited in claim 11, wherein said positional offset is independent of magnetic reference field strength.

14. A method as recited in claim 11, further comprising domain mapping said ratio to said positional offset.

15. A method as recited in claim 11:

wherein said magnetic reference comprises a magnetic infrastructure defining a roadway reference line; and

wherein said positional offset comprises lateral offset in relation to said roadway reference line.

16. A method as recited in claim 11, wherein said sensors comprise digital magnetometers.

17. A method as recited in claim 16, wherein said magnetometers comprise multiple-axis magnetometers.

18. A method as recited in claim 17, wherein said magnetometers are configured in an array.

19. A method as recited in claim 16, wherein each said magnetometer provides magnetic field strength readings in digital form for all available axes.

20. A method as recited in claim 19, wherein said magnetometers communicate said field strength readings to a digital data processor.

21. A method as recited in claim 20, wherein said digital data processor processes said field strength readings to obtain said positional offset.

22. A method for determining the position of an object relative to a magnetic reference, comprising:

sensing, with each of at least two sensors associated with an object, at least one axial field strength component of the magnetic field emitted from a magnetic reference;

computing a ratio of said sensed axial field strength components; and

determining a positional offset of said object from said magnetic reference as a function of said ratio;

wherein said positional offset is independent of magnetic reference field strength.

23. A method as recited in claim 22, wherein said ratio is dimensionless.

24. A method as recited in claim 22, further comprising domain mapping said ratio to said positional offset.

25. A method as recited in claim 22:

wherein said magnetic reference comprises a magnetic infrastructure defining a roadway reference line; and

wherein said positional offset comprises lateral offset in relation to said roadway reference line.

26. A method as recited in claim 22, wherein said sensors comprise digital magnetometers.

27. A method as recited in claim 26, wherein said magnetometers comprise multiple-axis magnetometers.

28. A method as recited in claim 27, wherein said magnetometers are configured in an array.

29. A method as recited in claim 26, wherein each said magnetometer provides magnetic field strength readings in digital form for all available axes.

30. A method as recited in claim 29, wherein said magnetometers communicate said field strength readings to a digital data processor.

31. A method as recited in claim 30, wherein said digital data processor processes said field strength readings to obtain said positional offset.

32. A method for determining the position of an object relative to a magnetic reference, comprising:

sensing, with each of at least two sensors associated with an object, at least one axial field strength component of the magnetic field emitted from a magnetic reference infrastructure defining a roadway reference line;

computing a ratio of said sensed axial field strength components;

mapping lateral offset of said object in relation to said magnetic reference to said field strength ratio, said mapping representing an inverse map of said lateral offset as a function of said ratio;

inverting said inverse mapping to provide a forward map of said lateral offset as a function of said ratio; and

determining said lateral offset of said object from said forward map;

wherein said lateral offset is independent of magnetic reference field strength.

33. A method as recited in claim 32, wherein said ratio is dimensionless.

34. A method as recited in claim 32, further comprising domain mapping said ratio to said positional offset.

35. A method as recited in claim 32, wherein said sensors comprise digital magnetometers.

36. A method as recited in claim 35, wherein said magnetometers comprise multiple-axis magnetometers.

37. A method as recited in claim 36, wherein said magnetometers are configured in an array.

38. A method as recited in claim 35, wherein each said magnetometer provides magnetic field strength readings in digital form for all available axes.

39. A method as recited in claim 38, wherein said magnetometers communicate said field strength readings to a digital data processor.

40. A method as recited in claim 39, wherein said digital data processor processes said field strength readings to obtain said positional offset.

41. An apparatus for determining the position of an object relative to a magnetic reference marker, comprising:

a sensor associated with an object;

said sensor configured for sensing at least one axial field strength component of the magnetic field emitted from a magnetic reference;

a digital data processor; and

programming associated with said digital data processor for

computing a ratio of said sensed axial field strength components, and

determining a positional offset of said object from said magnetic reference as a function of said ratio.

42. An apparatus as recited in claim 41, wherein said ratio is dimensionless.

43. An apparatus as recited in claim 41, wherein said positional offset is independent of magnetic reference field strength.

44. An apparatus as recited in claim 41, further comprising programming for domain mapping said ratio to said positional offset.

45. An apparatus as recited in claim 41:

wherein said magnetic reference comprises a magnetic infrastructure defining a roadway reference line; and

wherein said positional offset comprises lateral offset in relation to said roadway reference line.

46. An apparatus as recited in claim 41, wherein said sensor comprises a digital magnetometer.

47. An apparatus as recited in claim 45, wherein said magnetometer comprises a multiple-axis magnetometer.

48. An apparatus as recited in claim 46, wherein said magnetometer provides magnetic field strength readings in digital form for all available axes.

49. An apparatus as recited in claim 48, wherein said magnetometer is configured to communicate said field strength readings to said digital data processor.

50. An apparatus as recited in claim 49, wherein said digital data processor processes said field strength readings to obtain said positional offset.

51. An apparatus for determining the position of an object relative to a magnetic reference, comprising:

at least two sensors associated with an object;

each said sensor configured for sensing at least one axial field strength component of the magnetic field emitted from a magnetic reference;

a digital data processor; and

programming associated with said digital data processor for

computing a ratio of said sensed axial field strength components; and

determining said positional offset of said object from said magnetic reference as a function of said ratio.

52. An apparatus as recited in claim 51, wherein said ratio is dimensionless.

53. An apparatus as recited in claim 51, wherein said positional offset is independent of magnetic reference field strength.

54. An apparatus as recited in claim 51, further comprising programming for domain mapping said ratio to said positional offset.

55. An apparatus as recited in claim 51:

wherein said magnetic reference comprises a magnetic infrastructure defining a roadway reference line; and

wherein said positional offset comprises lateral offset in relation to said roadway reference line.

56. An apparatus as recited in claim 51, wherein said sensors comprise digital magnetometers.

57. An apparatus as recited in claim 56, wherein said magnetometers comprise multiple-axis magnetometers.

58. An apparatus as recited in claim 57, wherein said magnetometers are configured in an array.

59. An apparatus as recited in claim 56, wherein each said magnetometer provides magnetic field strength readings in digital form for all available axes.

60. An apparatus as recited in claim 59, wherein said magnetometers are configured to communicate said field strength readings to said digital data processor.

61. An apparatus as recited in claim 60, wherein said digital data processor processes said field strength readings to obtain said positional offset.

62. An apparatus for determining the position of an object relative to a magnetic reference, comprising:

at least two sensors associated with an object;

each said sensor configured for sensing at least one axial field strength component of the magnetic field emitted from a magnetic reference;

a digital data processor; and

programming associated with said digital data processor for

computing a ratio of said sensed axial field strength components; and

determining a positional offset of said object from said magnetic reference as a function of said ratio;

wherein said positional offset is independent of magnetic reference field strength.

63. An apparatus as recited in claim 62, wherein said ratio is dimensionless.

64. An apparatus as recited in claim 62, further comprising programming for domain mapping said ratio to said positional offset.

65. An apparatus as recited in claim 62:

wherein said magnetic reference comprises a magnetic infrastructure defining a roadway reference line; and

wherein said positional offset comprises lateral offset in relation to said roadway reference line.

66. An apparatus as recited in claim 62, wherein said sensors comprise digital magnetometers.

67. An apparatus as recited in claim 66, wherein said magnetometers comprise multiple-axis magnetometers.

68. An apparatus as recited in claim 67, wherein said magnetometers are configured in an array.

69. An apparatus as recited in claim 66, wherein each said magnetometer provides magnetic field strength readings in digital form for all available axes.

70. An apparatus as recited in claim 69, wherein said magnetometers are configured to communicate said field strength readings to said digital data processor.

71. An apparatus as recited in claim 70, wherein said digital data processor processes said field strength readings to obtain said positional offset.

72. An apparatus for determining the position of an object relative to a magnetic reference, comprising:

at least two sensors associated with an object;

each said sensor configured for sensing at least one axial field strength component of the magnetic field emitted from a magnetic reference infrastructure defining a roadway reference line;

a digital data processor; and

programming associated with said digital data processor for

computing a ratio of said sensed axial field strength components; and

determining lateral offset of said object from said magnetic reference as a function of said ratio by domain mapping said ratio to said positional offset;

wherein said lateral offset is independent of magnetic reference field strength.

73. An apparatus as recited in claim 72, wherein said ratio is dimensionless.

74. An apparatus as recited in claim 72, wherein said sensors comprise digital magnetometers.

75. An apparatus as recited in claim 74, wherein said magnetometers comprise multiple-axis magnetometers.

76. An apparatus as recited in claim 75, wherein said magnetometers are configured in an array.

77. An apparatus as recited in claim 74, wherein each said magnetometer provides magnetic field strength readings in digital form for all available axes.

78. An apparatus as recited in claim 77, wherein said magnetometers are configured to communicate said field strength readings to said digital data processor.

79. An apparatus as recited in claim 78, wherein said digital data processor processes said field strength readings to obtain said positional offset.