Position tracking system

• US 6,043,873 A
• Filed: 01/10/1997
• Issued: 03/28/2000
• Est. Priority Date: 01/10/1997
• Status: Expired due to Term

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: Advanced Optical Technologies, LLC
• Inventors: Rains, Jack C. Jr., Ramer, David P.
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/781,826
• Time in Patent Office: 1,173 Days
• Field of Search: 356/139.07, 356/140, 356/141.1, 356/141.2, 356/141.3, 356/152.1, 356/152.3
• US Class Current: 356/139.03
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49
• CPC Class Codes: G01S 7/4816 of receivers alone

Abstract

An optical position tracking system that tracks the position of objects, using light intensity and/or frequency with the application of geometry and ratios of detector responses, is provided, having light distributing and light detecting components that employ the concepts of constructive occlusion and diffuse reflection. Diffusely reflective cavities, masks and baffles are used to improve certain radiating characteristics of the distributing components and certain response characteristics of the detecting components, to tailor the radiation and detection profiles thereof, including them substantially uniform for all angles within a hemispheric area which the distributing and detecting components face. The distributing and/or detecting components are partitioned with specially-configured baffles. A partitioned distributor has distinct emission sections where the sections can emit spectrally-different or distinguishable radiation. A partitioned detector has distinct detection sections where the sections can detect radiation from different directions. The system may be variously configured, to use different combinations of partitioned and nonpartitioned devices. In most configurations, a single head module provides one set of directional data about two coordinates (e.g., ρ and Θ) for one reflector. An additional head module remotely positioned from the first head module can provide a second set of directional data for the reflector (e.g., ρ₂ and Θ₂), for cross-referencing with the first set of directional data to obtain positional data in three dimensions of the object being tracked. The system can also track multiple objects, using spectrally-different (or at least spectrally distinguishable reflectors) in conjunction with correspondingly spectrally-compatible sensors.

Claims

1. An optical position tracking system for determining the position of an object, comprising:

a reflector affixed to the object;

a light source;

a light detector having a detection surface, a mask positioned a predetermined distance from said detection surface, and a baffle positioned in a region between said mask and said detection surface, said baffle partitioning said region into sections, said light detector generating signals representative of light incident on said detection surface.

2. A position tracking system as defined in claim 1, wherein said light detector comprises a plurality of sensors, each generating signals representative of light incident on a distinct section.

3. A position tracking system as defined in claim 1, wherein said light source has an emitter surface and an emitter mask positioned a predetermined distance from said emitter surface.

4. A position tracking system as defined in claim 3, wherein said light source has a diffusely reflective emitter cavity having an emitter aperture that provides said emitter surface.

5. A position tracking system as defined in claim 1, wherein said light source comprises a scanning light mechanism.

6. A position tracking system as defined in claim 1, wherein said light source comprises a pulse emitter.

7. A position tracking system as defined in claim 1, wherein said light detector has a diffusely reflective detection cavity having a detection aperture that provides said detection surface, and said baffle includes an extended portion that divides said cavity.

8. A position tracking system as defined in claim 1, wherein said baffle includes two intersecting members that form four of said sections.

9. A position tracking system as defined in claim 1, wherein said mask and said baffle have diffusely reflective surfaces.

10. A position tracking system as defined in claim 1, further comprising a processor that processes said signals from said light detector.

11. A position tracking system as defined in claim 2, further including a second reflector, and said light detector includes a second plurality of sensors, each of said second sensors also generating signals representative of light incident on said respective distinct section.

12. A position tracking system as defined in claim 4, wherein said detector mask of said light detector has a structure that is configured with said emitter cavity of said light source.

13. A position tracking system for determining the position of an object, comprising:

a light source affixed to said object;

a light detector including;

a detection surface;

a mask positioned a predetermined distance from said detection surface;

a baffle positioned in a region between said mask and said detection surface, said baffle dividing said region into sections.

14. A position tracking system as defined in claim 13, wherein said light detector includes a diffusely reflective cavity having an aperture that provides said detection surface.

15. A position tracking system as defined in claim 14, wherein said baffle includes an extended portion that divides said cavity.

16. An optical position tracking system for determining the position of an object, comprising:

a reflector affixed to the object;

a diffusely reflective cavity having an aperture;

a mask positioned a predetermined distance from said aperture;

a light source;

a light detector;

a baffle having members that divide a region between said cavity and said mask into sections,

wherein said light detector generates signals representative of light incident on said aperture.

17. An optical position tracking system as defined in claim 16, wherein said light detector includes a plurality of sensors, each of which is associated with a distinct section.

18. An optical position tracking system as defined in claim 16, wherein said light source comprises a plurality of emitters, each positioned within a distinct section.

19. A position tracking system as defined in claim 16, wherein said light source emits pulses of radiation.

20. An optical position tracking system as defined in claim 16, wherein said baffle has a first portion extending below said aperture and a second portion extending above said aperture, said first portion dividing said cavity into lower sections, said second portion forming upper sections between said aperture and said mask, and said light detector comprises a plurality of sensors, each of which is positioned within a distinct upper section.

21. An optical position tracking system as defined in claim 16, wherein said baffle has a first portion extending below said aperture and a second portion extending above said aperture, said first portion dividing said cavity into lower sections, said second portion forming upper sections between said aperture and said mask, and said light source comprises a plurality of emitters, each of which is positioned within a distinct upper section.

22. A position tracking system as defined in claim 16, wherein said mask and said baffle have diffusely reflective surfaces.

23. A position tracking system as defined in claim 16, further comprising a processor processing said signals to provide directional data of said object.

24. A position tracking system as defined in claim 17, wherein said light source comprises a second diffusely reflective cavity having an emitter aperture and an emitter mask positioned a predetermined distance from said emitter aperture.

25. A position tracking system as defined in claim 18, wherein said light detector comprises a second diffusely reflective cavity having a detection aperture and a detection mask positioned a predetermined distance from said detection aperture.

26. A position tracking system as defined in claim 18, wherein each of said emitters is of a distinguishable spectral characteristic.

27. A position tracking system as defined in claim 17, further including a second reflector, wherein said light detector includes a second plurality of sensors, each of which is associated with a distinct section.

28. A position tracking system as defined in claim 17, wherein said sensors detect light intensity.

29. A position tracking system as defined in claim 16, wherein said light source emits pulses of radiation and said light detector measures elapsed time of said pulses.

30. A position tracking system as defined in claim 16, wherein said cavity is hemispherical.

31. A position tracking system as defined in claim 16, wherein said light source includes a scanning light mechanism.

32. A position tracking system for determining the position of an object, comprising:

a reflector affixed to said object;

a scanning light mechanism generating a radiation beam;

a light detector having two portions each configured to provide a diffusely reflective cavity defining an aperture and including a mask positioned above said aperture, said detector generating signals in response to detection of light;

a processor that processes said signals to provide directional data representative of a directional location of said reflector.

33. A position tracking system as defined in claim 32, wherein said scanning light mechanism includes a light source generating a light beam and a positioner that moves the light beam in a predetermined pattern.

34. A position tracking system for determining the position of an object, comprising:

a reflector affixed to the object;

a scanning light mechanism generating a radiation beam;

a light detector having two portions each configured to provide a diffusely reflective cavity defining an aperture and including a mask positioned above the aperture, the detector generating signals in response to detection of light, wherein each of the portions further includes a baffle that divides each of the cavities into lower sections and a region between the respective mask and the respective aperture into upper sections; and

a processor responsive to the signals for providing directional data representative of a directional location of the reflector.

35. A position tracking system for determining the position of an object, comprising:

a light source affixed to said object;

a light detector including a detection surface, a mask positioned a predetermined distance from said detection surface, and a baffle that divides a region between said detection surface and said mask into sections; and

a plurality of sensors, each associated with a distinct section.

36. A position tracking system as defined by claim 35, wherein said light detector includes a diffusely reflective cavity having an aperture that provides said detection surface, and said baffle has an extended portion that divides said cavity.

37. A position tracking system as defined in claim 36, wherein said cavity is hemispherical and has an interior surface that is diffusely reflective.

38. A position tracking system as defined in claim 35, wherein said baffle includes two intersecting planar members that form four sections.

39. A position tracking system as defined in claim 35, wherein said mask and said baffle have diffusely reflective surfaces.

40. A position tracking system as defined in claim 35, further comprising a processor, associated with the detector, for processing said signals to provide directional signals indicative of a directional location of said object.

41. An optical device, comprising:

a first structure having a first optical surface that faces a first direction;

a second structure having a second optical surface that faces a second direction;

said first and second structures situated angularly offset from each other wherein each of said structures masks the optical surface of the other from either emitted radiation from or incidental radiation on said other optical surface within a distinct range of angles relative to said optical device.

42. An optical detector in accordance with claim 41, wherein said first and second optical surfaces are substantially normal to each other.

43. An optical detector in accordance with claim 41, wherein said range of angles are substantially at an horizon defined relative to the device.

44. An optical detector comprising:

a detection structure of a closed configuration defining a nonoptical area therein, having at least two distinct substantially equal portions with substantially equal detection surfaces around said area, each of said portions generating a signal responsive to incidental radiation thereon and including;

a first detection surface and a second detection surface projecting therefrom at an angle wherein each of said first and second detection surfaces faces a nonparallel direction with respect to the other.

45. An optical detector of claim 44, wherein said direction of said second detection surface is parallel with an axis substantially normal to a plane defined by said area and said first detection surface is substantially normal to said first detection surface.

46. An optical detector of claim 44, wherein said detection structure is configured as a closed loop with four portions.

47. An optical detector of claim 44, wherein said angle is substantially 90 degrees.

48. An optical detector of claim 44, wherein said first detection surface faces inwardly toward said opening and said second detection surface faces substantially normally thereto.

49. An optical detector of claim 44 wherein said detection surface is sensitive to infrared radiation.

50. An optical detector, comprising:

a base configured with a plurality of separate detection surfaces;

a mask structure positioned a predetermined distance from all of said detection surfaces;

a plurality of detector elements, each of which provides signals representative of light incident on a distinct detection surface.

51. An optical detector as defined in claim 50, wherein said base includes a common plurality of diffusely reflective cavities, each of which provides a distinct detection surface and housing a distinct detector element.

52. An optical device, comprising:

a base configured with a plurality of separate emitter surfaces;

a mask structure positioned a predetermined distance from all of said emitter surfaces;

a plurality of emitter elements, each of which provides illumination for a distinct emitter surface.

53. An optical position tracking system comprising:

a source of light for association with an object to be tracked;

a light detector oriented to receive light from a predetermined area which includes the object to be tracked, said light detector comprising a sensor having an aperture and a mask constructively occluding said aperture in such a manner that a cross-sectional area of the aperture presented to incident light is substantially constant over a range of angles of incidence; and

processing circuitry for determining position of the source of light in response to a detection signal output of the sensor.

54. An optical position tracking system as in claim 53, wherein:

the source of light comprises a reflector for attachment to an object to be tracked; and

the system further comprises a illuminator providing substantially uniform illumination over all azimuths of a hemisphere covering the predetermined area.

55. An optical position tracking system as in claim 54, wherein the illuminator comprises an illumination source and a mask constructively occluding a portion of the illumination source.

56. An optical position tracking system comprising:

a reflector for attachment to an object to be tracked;

a light distributor, comprising an illumination source and a mask constructively occluding a portion of the illumination source, for uniformly illuminating all azimuths and elevations of a hemispherical region;

a light detector oriented to receive light reflections from within the region and provide a signal representative of a direction and intensity of incident light; and

processing circuitry for determining position of the reflector in response to a detection signal output of the sensor.

57. An optical position tracking system as in claim 56, wherein the light detector comprises:

a sensor having an aperture; and

a mask constructively occluding said aperture in such a manner that a cross-sectional area of the aperture presented to incident light reflections is substantially constant over a range of angles of incidence in a hemispherical region facing the light detector.

58. An optical position tracking system comprising:

a reflector for attachment to an object to be tracked;

a light distributor, comprising an illumination source and a mask constructively occluding a portion of the illumination source, for uniformly illuminating a predetermined area;

a light detector oriented to receive light reflections from the predetermined area, said light detector comprising a sensor having an aperture and a mask constructively occluding said aperture in such a manner that a cross-sectional area of the aperture presented to incident light reflections is substantially constant over a range of angles of incidence; and

processing circuitry for determining position of the reflector in response to a detection signal output of the sensor.

59. An optical position tracking system comprising:

a constructed occlusion irradiation device oriented to uniformly irradiate a predetermined region;

a constructed occlusion radiation detector oriented to uniformly sense radiation reflected from within the predetermined region; and

a processing system responsive to at least one output signal from the detector for determining a position of a reflective object within the predetermined region.

60. An optical position tracking system comprising:

a source of light for association with an object to be tracked;

a light detector oriented to receive light from a predetermined area which includes the object to be tracked, said light detector comprising a sensor having an aperture and a mask shielding a portion of said aperture from incident light in such a manner that a cross-sectional area of the aperture presented to incident light is substantially constant over a range of angles of incidence; and

processing circuitry for determining position of the source of light in response to a detection signal output of the sensor.

62. An optical position tracking system as in claim 60, wherein the light detector further comprises a diffusely reflective cavity oriented to redirect light toward the sensor, and an opening of the cavity defines the aperture.

65. An optical position tracking system as in claim 60, wherein:

the source of light comprises a reflector for attachment to an object to be tracked; and

the system further comprises an illuminator providing substantially uniform illumination over all azimuths of a hemisphere covering the predetermined area.

66. An optical position tracking system as in claim 60, wherein the source of light comprises a pulse emitter.

67. An optical position tracking system as in claim 60, wherein the source of light comprises a scanning light emitter.

68. An optical position tracking system as in claim 60, wherein the light detector differentiates light of different colors.

61. An optical position tracking system comprising:

a source of light for association with an object to be tracked;

a light detector oriented to receive light from a predetermined area which includes the object to be tracked, the light detector comprising;

a sensor having an aperture,

a mask shielding a portion of the aperture from incident light in such a manner that a cross-sectional area of the aperture presented to incident light is substantially constant over a range of angles of incidence, and

a light deflector positioned between the aperture and the mask; and

processing circuitry for determining position of the source of light in response to a detection signal output of the sensor.

63. An optical position tracking system comprising:

a source of light for association with an object to be tracked;

a light detector oriented to receive light from a predetermined area which includes the object to be tracked, the light detector comprising;

a sensor having an aperture,

a mask shielding a portion of the aperture from incident light in such a manner that a cross-sectional area of the aperture presented to incident light is substantially constant over a range of angles of incidence, and

a reflective baffle dividing a region between the aperture and the mask into a plurality of sub-regions;

processing circuitry for determining Position of the source of light in response to a detection signal output of the sensor,

wherein the sensor comprises a plurality of sensors each of which is oriented to sense light passing through a distinct one of the sub-regions.

64. An optical position tracking system as in claim 63, wherein the baffle divides the region into sections.

69. An optical position tracking system comprising:

a reflector for attachment to an object to be tracked;

a light distributor, comprising an illumination source and a mask intercepting light from a portion of the illumination source, such that the light distributor uniformly illuminates all azimuths and elevations of a hemispherical region;

a light detector oriented to receive light reflections from within the region and provide at least one signal representative of direction and intensity of incident light; and

processing circuitry for determining position of the reflector in response to a detection signal output of the detector.

70. An optical position tracking system as in claim 69, wherein the light detector comprises:

a sensor having an aperture; and

a mask shielding a portion of said aperture in such a manner that a cross-sectional area of the aperture presented to incident light reflections is substantially constant over a range of angles of incidence in a hemispherical region facing the light detector.

71. An optical position tracking system as in claim 69, wherein the distributor further comprises a light deflector positioned between the illumination source and the mask.

72. An optical position tracking system as in claim 69, wherein:

the light distributor further comprises a reflective baffle dividing a region between the illumination source and the mask into a plurality of sub-regions, and

the illumination source comprises a plurality of emitters each of which is oriented to radiate through a distinct one of the sub-regions.

73. An optical position tracking system as in claim 72, wherein the baffle divides the region into sections.

74. An optical position tracking system comprising:

a reflector for attachment to an object to be tracked;

a light distributor, comprising an illumination source and a mask intercepting light from a portion of the illumination source, such that the light distributor uniformly illuminates a predetermined area;

a light detector oriented to receive light reflections from the predetermined area, said light detector comprising a sensor having an aperture and a mask shielding a portion of said aperture from incident light in such a manner that a cross-sectional area of the aperture presented to incident light reflections is substantially constant over a range of angles of incidence; and

processing circuitry for determining position of the reflector in response to a detection signal output of the sensor.

75. An optical position tracking system as in claim 74, wherein the light detector further comprises a light deflector positioned between the aperture and the detector mask.

76. An optical position tracking system as in claim 75, wherein:

the light deflector comprises a reflective baffle dividing a region between the aperture and the detector mask into a plurality of sub-regions, and

the sensor comprises a plurality of sensors each of which is oriented to sense light passing through a distinct one of the sub-regions.

77. An optical position tracking system as in claim 76, wherein the baffle divides the region into sections.

78. An optical position tracking system as in claim 75, wherein the light detector further comprises a diffusely reflective cavity redirecting incident light toward the sensor, an opening of the cavity defining the aperture.

79. An optical position tracking system as in claim 74, wherein the distributor further comprises a light deflector positioned between the illumination source and the distributor mask.

80. An optical position tracking system as in claim 79, wherein:

the light deflector comprises a reflective baffle dividing a region between the illumination source and the distributor mask into a plurality of sub-regions, and

the illumination source comprises a plurality of emitters each of which is oriented to radiate through a distinct one of the sub-regions.

81. An optical position tracking system as in claim 80, wherein the baffle divides the region into sections.

82. An optical position tracking system as in claim 79, wherein the illumination source comprises a diffusely reflective cavity and an emitter for radiating light into the cavity, the distributor mask intercepting light emerging from an opening of the cavity.

83. An optical position tracking system as in claim 81, wherein the emitter radiates pulses of light into the cavity.

84. A position tracking system for determining azimuthal position of an object relative to the system, comprising:

a light source associated with said object;

a light detector including;

a detection surface;

a mask positioned a predetermined distance from said detection surface;

a baffle positioned in a region between said mask and said detection surface, said baffle dividing said region into sections.

85. An optical position tracking system as in claim 84, wherein the surface has a surface width and the mask has a mask width, said mask width being greater than said surface width.

86. An optical position tracking system as in claim 84, wherein the surface has a surface width and the mask has a mask width, said mask width being lesser than said surface width.

87. An optical position tracking system as in claim 84, wherein the surface has a surface width and the mask has a mask width, said mask width being substantially equal to said surface width.

88. An optical position tracking system as in claim 84, further comprising a cavity having an aperture that provides said surface, said baffle dividing said cavity into active and nonactive sections.

89. An optical position tracking system as in claim 88, wherein each of said active sections houses an optical element.