Method and apparatus for determining position and orientation

• US 5,856,844 A
• Filed: 09/19/1996
• Issued: 01/05/1999
• Est. Priority Date: 09/21/1995
• Status: Expired due to Term

• Current Assignee: Omniplanar, Inc. (Honeywell International Inc.)
• Original Assignee: Omniplanar, Inc. (Honeywell International Inc.)
• Inventors: Dunphy, Robert H., Batterman, Eric P., Chandler, Donald G.
• Primary Examiner(s): BRITTON, HOWARD W
• Application Number:
  US08/715,846
• Time in Patent Office: 838 Days
• Field of Search: 348/207, 348/42, 348/94, 348/95, 348/135, 348/139, 348/140, 348/142, 348/169, 901/47, 395/94, 364/559, 345/156, 345/158, 382/148, 382/151, 382/287
• US Class Current: 348/207.99
• CPC Class Codes: A63F 2300/1062 being specially adapted to a type of game, e.g. steering wheel
• CPC Class Codes: A63F 2300/807 Role playing or strategy games
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G06F 3/012 Head tracking input arrangements
• CPC Class Codes: G06F 3/0325 using a plurality of light emitters or reflectors or a plurality of detectors forming a reference frame from which to derive the orientation of the object, e.g. by triangulation or on the basis of reference deformation in the picked up image
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G09B 9/307 by helmet-mounted projector or display G09B9/36 takes precedence; optical parts of head-up displays G02B27/01
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

A method for determining degrees of freedom of an object, and in particular, to a device for determining up to six degrees of freedom of a head mount display and a handle. A first camera is attached to a head mount display and senses an optically modulated target. The first camera'"'"'s video output signal is processed with a digital computer to determine the position and orientation of the head mount display. A second camera is attached to a head mount display and senses an optically modulated target attached to a handle. The second camera'"'"'s video output signal is processed with a digital computer to determine the position and orientation of the handle.

Claims

1. In a system for determining at least three degrees of freedom of a camera relative to a reference frame, said system having a plurality of optically modulated targets wherein each target of said plurality of optically modulated targets has a respective spatial relationship to said reference frame, a method wherein any unknown spatial relationship of any of said plurality of optically modulated targets to said reference frame is determined using at least one optically modulated target with a known spatial relationship to said reference frame, and wherein said known and said unknown optically modulated targets are simultaneously within said camera'"'"'s field of view.

2. The method of claim 1 wherein the spatial relationship to said reference frame of said optically modulated targets are updated adaptively over time.

3. A method for determining at least three degrees of freedom of a handle relative to a camera, wherein an optically modulated target is attached to said handle, said method comprising,

(a) sensing at least a portion of said optically modulated target using said camera to produce a video signal, and

(b) processing said video signal using digital computing means.

4. The method of claim 3 wherein said camera is mounted to a head mount display.

5. The method of claim 3 wherein said optically modulated target comprises at least one larger pattern and at least one smaller pattern.

6. The method of claim 3 wherein said at least one larger pattern is used to determine said at least three degrees of freedom of said handle when said handle is relatively far from said camera, and wherein said at least one smaller pattern is used to determine said at least three degrees of freedom of said handle when said handle is relatively close to said camera.

7. The method of claim 3 wherein said optically modulated target is asymmetric, whereby any ambiguity in the determination of said at least three degrees of freedom of said handle is eliminated.

8. The method of claim 3 wherein said camera has a field of view of at least about 100 degrees.

9. The method of claim 3 wherein said camera comprises an optical imaging means, said optical imaging means producing a predetermined geometric distortion, wherein said processing of said video signal comprises

determining first coordinates of a first point, and

computing second coordinates of a second point, wherein said second coordinates depend upon said first coordinates, and upon said predetermined geometric distortion.

10. The method of claim 3 wherein said optically modulated target comprises a plurality of patterns, said method further comprising combining numeric values determined from at least two patterns of said plurality of patterns to determine said at least three degrees of freedom.

11. The method of claim 3 wherein a plurality of optically modulated targets are attached to said handle, and wherein sensing any one of said plurality of optically modulated targets is sufficient to determine said at least three degrees of freedom of said handle to said camera.

12. The method of claim 3 wherein said optically modulated target has spatially varying optical transmittance, and wherein at least a portion of light emitted by a light source is transmitted through said optically modulated target to said camera.

13. The method of claim 3 wherein said optically modulated target comprises a plurality of patterns, and wherein sensing any one of said plurality of patterns is sufficient to determine said at least three degrees of freedom of said handle.

14. The method of claim 13 wherein each pattern of said plurality of patterns is uniquely identifiable.

15. The method of claim 3 wherein said optically modulated target has spatially varying optical reflectance, and wherein at least a portion of light emitted by a light source is reflected by said optically modulated target to said camera.

16. The method of claim 15, wherein said light source is attached to said camera.

17. The method of claim 15, wherein said optically modulated target comprises a retroreflector.

18. The method of claim 3, wherein said handle comprises regions of selectively changeable optical properties, wherein said changeable optical properties are detected by said camera.

19. The method of claim 18 wherein said detected changeable optical properties signal a computer.

20. The method of claim 18 wherein said regions are changed by selectively covering or exposing retroreflective marks.

21. The method of claim 18 wherein said regions are selectively covered or exposed by a mechanical trigger.

22. The method of claim 18 wherein said regions of changeable optical properties are selectively covered or exposed by use of a mechanical button.

23. The method of claim 18, wherein said regions of changeable optical properties are comprised of lights which are controlled by an operator of said handle.

24. The method of claim 18 wherein said regions of changeable optical properties are selectively partially covered or exposed.

25. The method of claim 24 wherein said detected changeable optical properties proportionally signal a computer.

26. A method for determining at least three degrees of freedom of a handle to a reference frame, wherein a first optically modulated target is attached to said handle, said reference frame having a known spatial relationship to a second optically modulated target, said method comprising,

(a) sensing at least a portion of said first optically modulated target using a camera to determine at least three degrees of freedom of said handle to said camera,

(b) sensing at least a portion of said second optically modulated target using said camera to determine at least three degrees of freedom of said camera to said reference frame, and

(c) combining the degrees of freedom from steps a and b to produce at least three degrees of freedom of said handle to said reference frame.

27. The method of claim 26 wherein a first camera is mounted in a known physical relation to a second camera, wherein at least a portion of said first optically modulated target is sensed with said first camera to determine at least three degrees of freedom of said handle to said first camera, and wherein at least a portion of said second optically modulated target is sensed with said second camera to determine at least three degrees of freedom of said second camera to reference frame.

28. The method of claim 27 wherein a single processor processes video signals produced by said first and second cameras.