Apparatus and method for determining orientation parameters of an elongate object

• US 20050195387A1
• Filed: 03/08/2004
• Published: 09/08/2005
• Est. Priority Date: 03/08/2004
• Status: Active Grant

• Current Assignee: Electronic Scripting Products, Inc.
• Original Assignee: Electronic Scripting Products, Inc.
• Inventors: Mandella, Michael J., Gonzalez-Banos, Hector H., Buermann, Dale H., Carl, Stewart R., Zhang, Guanghua G.
• Granted Patent: US 7,023,536 B2
• Time in Patent Office: Days
• US Class Current: 356/138
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/272 using photoelectric detection means
• CPC Class Codes: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G06F 3/0304 Detection arrangements using opto-electronic means constructional details of pointing devices not related to the detection arrangement using opto-electronic means G06F3/033; optical digitisers G06F3/042
• CPC Class Codes: G06F 3/03545 Pens or stylus

Abstract

An apparatus and method employing principles of stereo vision for determining one or more orientation parameters and especially the second and third Euler angles θ, ψ of an elongate object whose tip is contacting a surface at a contact point. The apparatus has a projector mounted on the elongate object for illuminating the surface with a probe radiation in a known pattern from a first point of view and a detector mounted on the elongate object for detecting a scattered portion of the probe radiation returning from the surface to the elongate object from a second point of view. The orientation parameters are determined from a difference between the projected and detected probe radiation such as the difference between the shape of the feature produced by the projected probe radiation and the shape of the feature detected by the detector. The pattern of probe radiation is chosen to provide information for determination of the one or more orientation parameters and can include asymmetric patterns such as lines, ellipses, rectangles, polygons or the symmetric cases including circles, squares and regular polygons. To produce the patterns the projector can use a scanning arrangement or a structured light optic such as a holographic, diffractive, refractive or reflective element and any combinations thereof. The apparatus is suitable for determining the orientation of a jotting implement such as a pen, pencil or stylus.

Claims

1. An apparatus for determining at least one orientation parameter of an elongate object having a tip contacting a surface at a contact point, said apparatus comprising:

a) a projector on said elongate object for illuminating said surface with a probe radiation in a predetermined pattern from a first point of view;

b) a detector on said elongate object for detecting a scattered portion of said probe radiation returning from said surface to a second point of view;

c) a unit for determining said at least one orientation parameter from a difference between said probe radiation and said scattered portion.

2. The apparatus of claim 1, wherein said at least one orientation parameter comprises an inclination angle θ

between an axis of said elongate object and a normal to said surface at said contact point.

3. The apparatus of claim 2, wherein said at least one orientation parameter further comprises a roll angle ψ

around said axis.

4. The apparatus of claim 1, wherein said surface comprises a plane surface.

5. The apparatus of claim 1, wherein said predetermined pattern comprises an asymmetric pattern.

6. The apparatus of claim 5, wherein said asymmetric pattern is selected from the group consisting of line sets, ellipses, rectangles and polygons.

7. The apparatus of claim 1, wherein said projector comprises a structured light optic for projecting said probe radiation onto said plane surface in said predetermined pattern.

8. The apparatus of claim 7, wherein said structured light optic comprises at least one element selected from the group consisting of holographic elements, diffractive elements, refractive elements and reflective elements.

9. The apparatus of claim 1, wherein said elongated object is selected from the group consisting of jotting implements, pointers, robotic arms and canes.

10. The apparatus of claim 9, wherein said jotting implements are selected from the group consisting of pens, pencils and styluses.

11. An apparatus for determining at least one orientation parameter of an elongate object having a tip contacting a plane surface, and a normal to said plane surface, said apparatus comprising:

a) a projector on said elongate object for illuminating said plane surface with a probe radiation at an angle σ

to said axis;

b) a detector on said elongate object offset from said projector for detecting a scattered portion of said probe radiation returning from said plane surface at a predetermined scatter angle τ

to said axis;

c) a timing unit for deriving said at least one orientation parameter from a detection time of said scattered portion.

12. The apparatus of claim 11, wherein said at least one orientation parameter comprises an inclination angle θ

between an axis of said elongate object and a normal to said surface at said contact point.

13. The apparatus of claim 12, wherein said at least one orientation parameter further comprises a roll angle ψ

around said axis.

14. The apparatus of claim 11, further comprising a scanning arrangement for varying said angle σ

in a scan pattern.

15. The apparatus of claim 14, wherein said scanning arrangement comprises a uniaxial scanner for varying said angle σ

by introducing an x-deflection γ

_x.

16. The apparatus of claim 14, wherein said scanning arrangement comprises a biaxial scanner for varying said angle σ

by introducing an x-deflection γ

_x and a y-deflection γ

_y.

17. The apparatus of claim 14, wherein said scanning arrangement comprises a biaxial scanner for varying said angle σ

and said scan pattern is selected from the group consisting of raster scan patterns, line scan patterns and Lissajous figures.

18. The apparatus of claim 11, wherein said projector comprises a structured light optic for projecting said probe radiation onto said plane surface in a predetermined pattern.

19. The apparatus of claim 18, wherein said structured light optic comprises at least one element selected from the group consisting of holographic elements, diffractive elements, refractive elements and reflective elements.

20. The apparatus of claim 18, wherein said predetermined pattern is selected from the group consisting of line sets, ellipses, rectangles and polygons.

21. The apparatus of claim 11, wherein said projector is mounted above said detector.

22. The apparatus of claim 11, wherein said detector further comprises a narrow field angle reception unit for admitting to said detector only said scattered portion returning from said plane surface at said predetermined scatter angle τ

.

23. The apparatus of claim 22, wherein said narrow field angle reception unit is selected from the group consisting of a cylindrical lens, a collimating lens, a thick aperture, a system of apertures, and a slit.

24. The apparatus of claim 11, wherein said detector comprises a photodetector array.

25. The apparatus of claim 24, further comprising a centroid computation unit for determining a centroid of said scattered portion.

26. The apparatus of claim 11, further comprising an optic for shaping said probe radiation into a scan beam.

27. The apparatus of claim 11, wherein said elongated object is selected from the group consisting of jotting implements, pointers, robotic arms and canes.

28. The apparatus of claim 27, wherein said jotting implements are selected from the group consisting of pens, pencils and styluses.

29. The apparatus of claim 11, wherein said timing unit is located on said elongate object.

30. The apparatus of claim 11, wherein said projector comprises a single frequency emitter for emitting said probe radiation at a single frequency f.

31. A method for determining at least one orientation parameter of an elongate object having a tip contacting a surface at a contact point, said method comprising:

a) illuminating said surface with a probe radiation in a predetermined pattern from a first point of view on said elongate object;

b) detecting a scattered portion of said probe radiation returning from said surface at a second point of view on said elongate object;

c) determining said at least one orientation parameter from a difference between said probe radiation and said scattered portion.

32. The method of claim 31, wherein said predetermined pattern is a scan pattern.

33. The method of claim 31, wherein said predetermined pattern comprises an asymmetric pattern.

34. The method of claim 31, wherein said at least one orientation parameter comprises at least one Euler angle.

35. A method for determining an inclination angle θ

between an axis of an elongate object having a tip contacting a plane surface, and a normal to said plane surface, said method comprising;

a) providing a projector on said elongate object;

b) providing a detector on said elongate object, said detector being offset from said projector;

c) illuminating said plane surface with a probe radiation at an angle σ

to said axis from said projector;

d) detecting a scattered portion of said probe radiation returning from said plane surface at a predetermined scatter angle τ

to said axis with said detector;

e) a timing unit for deriving said inclination angle θ

from a detection time of said scattered portion.

36. The method of claim 35, wherein said angle σ

is varied in a scan pattern.

37. The method of claim 36, wherein said scan pattern is selected from the group of uniaxial scan patterns and biaxial scan patterns.