Position and orientation determination using stationary fan beam sources and rotating mirrors to sweep fan beams

• US 6,473,167 B1
• Filed: 06/14/2001
• Issued: 10/29/2002
• Est. Priority Date: 06/14/2001
• Status: Active Grant

• Current Assignee: Ascension Technology Corporation (Roper Technologies, Inc.)
• Original Assignee: Ascension Technology Corporation (Roper Technologies, Inc.)
• Inventors: Odell, Don
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US09/880,146
• Time in Patent Office: 502 Days
• Field of Search: 356/141.4, 356/141.1, 356/139.03
• US Class Current: 356/141.4
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

Position and orientation determination uses stationary fan beam sources and rotating mirrors to sweep fan beams. In a first embodiment, a single motor has an elongated drive shaft with mirrors mounted on it, the reflective faces of which lie either in common planes or face in opposite directions. Fan beams are generated by stationary laser beam sources aimed at each mirror. As the mirrors rotate, each stationary source is reflected off a particular mirror and into a measuring space in a predictable pattern of movement. Electrical circuitry is provided with knowledge of the rotative position of the mirrors at any given time. A sensor attached to the object to be measured detects time of arrival of impinging scanning beams. At least one of the fan-shaped beams is skewed with respect to other beams, and at least two of the fan-shaped beams have origins sufficiently separated to allow accurate triangulation of the position and orientation of the sensor over various regions of the measuring space. In this way, accurate measurement of position and orientation may be carried out. In a second embodiment, separate drive motors are provided, each of which carries a mirror with the drive shafts of the motors preferably being parallel to one another and with the reflective surfaces of the mirrors lying in either common planes or parallel planes. A method is also disclosed.

Claims

1. A system for determining the position and orientation of an object within a space, comprising:

a) at least three fixed sources of light beams, a plane of at least one of said sources being skewed with respect to a plane of at least another one of said sources;

b) means for moving said light beams in said space in prescribed patterns of movement, said moving means comprising motor means for rotating drive shaft means comprising a single drive shaft, reflector means mounted on said drive shaft means for reflecting light from said at least three sources of light beams, said reflector means comprising a first reflective surface means for reflecting light from a plurality of light beam sources and at least a second reflective surface means for reflecting light from at least one additional light beam source;

c) sensor means associated with an object in said space for sensing time of arrival of each light beam at said object, said sensor means sending arrival signals indicative of said times of arrival;

d) control means for receiving said arrival signals, said control means being programmed with data regarding said patterns of movement and from said arrival signals and data calculating position and orientation of said object.

2. The system of claim 1, wherein said ref lector means reflects said beams into said space, rotation of said reflector means moving said beams in said prescribed patterns.

3. The system of claim 2, wherein said motor means comprises a single motor, said shaft means comprising a single shaft rotated by said motor.

4. The system of claim 1, wherein said reflector means comprises a mirror mounted on said shaft.

5. The system of claim 1, wherein said reflector means comprises a plurality of mirrors mounted on said shaft.

6. The system of claim 5, wherein said mirrors lie in a common plane.

7. The system of claim 5, wherein said mirrors face in opposite directions.

8. The system of claim 5, wherein said plurality of mirrors comprise four mirrors.

9. The system of claim 2, wherein said motor means comprises two motors, said shaft means comprising a separate shaft rotated by each of said motors.

10. The system of claim 9, wherein said reflector means comprises a mirror mounted on each shaft.

11. The system of claim 9, wherein said reflector means comprises a plurality of mirrors mounted on each shaft.

12. The system of claim 11, wherein mirrors mounted on each shaft are co-planar.

13. The system of claim 11, wherein mirrors mounted on each shaft face in opposite directions.

14. The system of claim 11, wherein said plurality of mirrors on each shaft comprise four mirrors.

15. The system of claim 11, wherein mirrors on at least one of said shafts are co-planar.

16. The system of claim 11, wherein mirrors on at least one of said shafts face in opposite directions.

17. The system of claim 1, wherein said sensor means comprises three light detectors mounted on said object.

18. The system of claim 1, wherein said sensor means comprises three retro-reflectors mounted on said object and light detector means located adjacent said moving means for detecting light reflected from said retro-reflectors.

19. The system of claim 18, wherein said moving means comprises a plurality of rotating mirrors and said light detector means comprises a light detector located adjacent each mirror.

20. The system of claim 1, wherein said control means comprises a computer.

21. The system of claim 9, wherein said shafts are parallel.

22. A method for determining the position and orientation of an object within a space including the steps of:

a) providing at least three fixed sources of light beams, an axis of at least one of said sources being skewed with respect to an axis of at least another one of said sources;

b) providing means for moving said light beams in said space in prescribed patterns of movement, said moving means comprising motor means for rotating drive shaft means comprising a single drive shaft, reflector means mounted on said drive shaft means for reflecting light from said at least three sources of light beams, said reflector means comprising a first reflective surface means for reflecting light from a plurality of light beam sources and at least a second reflective surface means for reflecting light from at least one additional light beam source;

c) providing sensor means associated with an object in said space for sensing time of arrival of each light beam;

d) programming control means with data regarding said patterns of movement;

e) moving said light beams in said prescribed patterns of movement;

f) sensing time of arrival of each light beam at said object;

g) conveying information regarding said times of arrival to said control means;

h) from said data and information, calculating position and orientation of said object.

23. The method of claim 22, wherein said reflector means reflects said beams into said space, rotation of said reflector means moving said beams in said prescribed patterns.

24. The method of claim 23, wherein said motor means comprises a single motor, said shaft means comprising a single shaft rotated by said motor.

25. The method of claim 23, wherein said reflector means comprises a mirror mounted on said shaft.

26. The method of claim 23, wherein said reflector means comprises a plurality of mirrors mounted on said shaft.

27. The method of claim 26, wherein said mirrors lie in a common plane.

28. The method of claim 26, wherein said mirrors face in opposite directions.

29. The method of claim 23, wherein said motor means comprises two motors, said shaft means comprising a separate shaft rotated by each of said motors.

30. The method of claim 29, wherein said separate shafts are parallel.

31. The method of claim 29, wherein said reflector means comprises a mirror mounted on each shaft.

32. The method of claim 29, wherein said reflector means comprises a plurality of mirrors mounted on each shaft.

33. The method of claim 32, wherein mirrors mounted on each shaft are co-planar.

34. The method of claim 32, wherein mirrors mounted on each shaft face in opposite directions.

35. The method of claim 32, wherein mirrors on at least one of said shafts are co-planar.

36. The method of claim 32, wherein mirrors on at least one of said shafts face in opposite directions.