Position tracking system

• US 6,266,136 B1
• Filed: 02/14/2000
• Issued: 07/24/2001
• 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: Ramer, David P., Rains, Jack C. Jr.
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US09/503,708
• Time in Patent Office: 526 Days
• Field of Search: 356/139.03, 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 to distinguish between data collected for each reflector. Numerous variations particularly on the concept of constructive occlusion may be accomplished with varying results as desired or appropriate. By reconfiguring the radiation/detection surface, the cavity, the mask and/or the baffle, the radiation/detection profile may be varied in substantially unlimited ways.

Claims

1. A position tracking system, comprising:

a radiant energy detecting transducer;

a radiant energy emitting transducer for causing radiant energy to be directed from an object to be tracked toward the detecting transducer; and

a processing circuit coupled to the detecting transducer, for processing at least one received-energy responsive signal produced by the detecting transducer to determine the position of the object to be tracked, wherein one of the transducers comprises;

(a) a base having a diffuse active optical area which faces substantially toward at least a portion of an intended field of operation of the one transducer;

(b) a mask spaced from the base and positioned to occlude a portion of the active optical area of the base with respect to the portion of the intended field of operation, the mask having a reflective surface facing substantially toward the portion of the active optical area of the base;

(c) a diffusely reflective cavity formed in one of the active optical area of the base and the reflective surface of the mask; and

(d) an electromagnetic transducer for transducing between radiant energy associated with the active optical area and corresponding electrical signals.

2. A position tracking system as in claim 1, wherein the radiant energy emitting transducer is adapted for mounting in close association with the object to be tracked.

3. A position tracking system as in claim 1, wherein the radiant energy emitting transducer comprises a radiant energy source, and a radiant energy reflector adapted for mounting in close association with the object to be tracked.

4. A position tracking system as in claim 3, wherein the radiant energy source comprises the base, the mask, the cavity and the electromagnetic transducer.

5. A position tracking system as in claim 1, wherein the detecting transducer comprises the base, the mask, the cavity and the electromagnetic transducer.

6. A position tracking system as in claim 5, wherein:

the detecting transducer further comprises a baffle located between the mask and the base for optically dividing the active optical area into a plurality of regions; and

the electromagnetic transducer comprises a plurality of radiant energy detectors, each optically coupled to a corresponding one of the regions, for transducing between radiant energy associated with the corresponding region of the active optical area and electrical signals.

7. A position tracking system as in claim 1, wherein:

the emitting transducer comprises the base, the mask, the cavity and the electromagnetic transducer;

the emitting transducer further comprises a baffle located between the mask and the base for optically dividing the active optical area into a plurality of regions; and

the electromagnetic transducer comprises a plurality of radiant energy emitters, each optically coupled to a corresponding one of the regions, for emitting radiant energy into the corresponding region of the active optical area in response to electrical signals.

8. A position tracking system as in claim 1, wherein the emitting transducer comprises a source of substantially continuous broad band radiant energy.

9. A position tracking system as in claim 1, wherein the emitting transducer comprises a pulse source of broad band radiant energy.

10. A position tracking system as in claim 1, wherein the mask and an aperture of the cavity are arranged so as to tailor a predetermined performance characteristic of the one transducer over an operative field of the one transducer.

11. A position tracking system as in claim 10, wherein the tailored performance characteristic provides a substantially uniform performance of the one transducer over a range of angles with respect to the one transducer.

12. A position tracking system as in claim 10, wherein the tailored performance characteristic provides a substantially non-uniform performance of the one transducer over a range of angles with respect to the one transducer.

13. A position tracking system as in claim 12, wherein the substantially non-uniform performance of the one transducer provides an increase in efficiency in regions on or about an axis of the one transducer.

14. A position tracking system as in claim 12, wherein the one transducer is the radiant energy detecting transducer.

15. A position tracking system as in claim 1, wherein:

the radiant energy emitting transducer comprises a plurality of electromagnetic transducers for transducing from electrical signals to corresponding radiant energy signals; and

each of the electromagnetic transducers emits radiant energy signals having a difference in a predetermined characteristic from radiant energy signals emitted from the others of the electromagnetic transducers.

16. A position tracking system as in claim 15, wherein the radiant energy signals emitted from the electromagnetic transducers comprise light, and the difference in the predetermined characteristic comprises a difference in color or wavelengths.

17. A position tracking system as in claim 15, wherein the difference in the predetermined characteristic comprises a difference in a pulsing rate.

18. A position tracking system as in claim 15, wherein the difference in the predetermined characteristic comprises a difference in temporal frequency.

19. A position tracking system, comprising:

a radiant energy detecting transducer;

a radiant energy emitting transducer for causing radiant energy to be directed from an object to be tracked toward the detecting transducer; and

a processing circuit coupled to the detecting transducer, for processing at least one received-energy responsive signal produced by the detecting transducer to determine the position of the object to be tracked, wherein one of the transducers comprises;

(a) a base having a diffuse active optical area which faces substantially toward at least a portion of an intended field of operation of the one transducer;

(b) a mask having a reflective surface spaced from the base and positioned to occlude a portion of the active optical area of the base with respect to the portion of the intended field of operation; and

(c) an electromagnetic transducer for transducing between radiant energy associated with the active optical area and corresponding electrical signals.

20. A position tracking system as in claim 19, wherein the emitting transducer comprises a source of substantially continuous broad band radiant energy.

21. A position tracking system as in claim 19, wherein the emitting transducer comprises a pulse source of broad band radiant energy.

22. A position tracking system as in claim 19, wherein the mask and the active optical area of the base are arranged so as to tailor a predetermined performance characteristic of the one transducer over a operative field of the one transducer.

23. A position tracking system as in claim 22, wherein the tailored performance characteristic provides a substantially uniform performance of the one transducer over a range of angles with respect to the one transducer.

24. A position tracking system as in claim 22, wherein the tailored performance characteristic provides a substantially non-uniform performance of the one transducer over a range of angles with respect to the one transducer.

25. A position tracking system as in claim 24, wherein the substantially non-uniform performance of the one transducer provides an increase in efficiency in regions on or about an axis of the one transducer.

26. A position tracking system as in claim 24, wherein the one transducer is the radiant energy detecting transducer.

27. A position tracking system as in claim 19, wherein:

the radiant energy emitting transducer comprises a plurality of electromagnetic transducers for transducing from electrical signals to corresponding radiant energy signals; and

each of the electromagnetic transducers emits radiant energy signals having a difference in a predetermined characteristic from radiant energy signals emitted from the others of the electromagnetic transducers.

28. A position tracking system as in claim 27, wherein the radiant energy signals emitted from the electromagnetic transducers comprise light, and the difference in the predetermined characteristic comprises a difference in color or wavelengths.

29. A position tracking system as in claim 27, wherein the difference in the predetermined characteristic comprises a difference in a pulsing rate.

30. A position tracking system as in claim 27, wherein the difference in the predetermined characteristic comprises a difference in temporal frequency.

31. A position tracking system, comprising:

a light detector comprising;

1) a detection surface,

2) a mask positioned a predetermined distance from the detection surface,

3) a baffle that divides a region between said detection surface and said mask into sections, and

4) a plurality of sensors, each associated with a distinct one of the sections; and

a plurality light sources for causing light to be directed from one or more objects to be tracked toward the light detector, wherein each of the light sources emits light having a difference in a predetermined characteristic from light emitted from the others of the sources.

32. A position tracking system as in claim 31, wherein the difference in the predetermined characteristic comprises a difference in color or wavelengths of light.

33. A position tracking system as in claim 31, wherein the difference in the predetermined characteristic comprises a difference in pulsing rate.

34. A position tracking system as in claim 31, wherein the difference in the predetermined characteristic comprises a difference in temporal frequency.

35. A position tracking system as in claim 31, wherein the one transducer further comprises a diffusely reflective cavity formed in the detection surface of the mask.

36. A position tracking system, comprising:

a radiant energy detecting transducer;

a radiant energy emitting transducer for causing radiant energy to be directed from an object to be tracked toward the detecting transducer; and

a processing circuit coupled to the detecting transducer, for processing at least one received-energy responsive signal produced by the detecting transducer to determine the position of the object to be tracked, wherein one of the transducers comprises;

(a) a base having an optical area which faces substantially toward at least a portion of an intended field of operation of the one transducer;

(b) a mask having a reflective surface spaced from the base and positioned to occlude a portion of the optical area of the base with respect to the portion of the intended field of operation, wherein the mask and the optical area of the base are configured to tailor a predetermined performance characteristic of the one transducer over an operative field of the one transducer

(c) a baffle located between the mask and the base for dividing a region between the reflective surface of the mask and the optical area of the base into a plurality of sections; and

(d) a plurality of electromagnetic transducers for transducing between radiant energy and corresponding electrical signals, at least one of the electromagnetic transducers being coupled to each of the sections.

37. A position tracking system as in claim 36, wherein said one transducer further comprises a diffusely reflective cavity formed in one of the optical area of the base and the reflective surface of the mask.

38. A position tracking system as in claim 37, wherein:

an aperture of the cavity forms the optical area of the base; and

the baffle extends between the aperture and the reflective surface of the mask.

39. A position tracking system as in claim 37, wherein:

an aperture of the cavity forms the optical area of the base; and

the baffle extends from the reflective surface of the mask through the aperture of the cavity.

40. A position tracking system as in claim 39, wherein the baffle extends to substantially abut an interior surface of the cavity.