Determination of an orientation parameter of an elongate object with a scan beam apparatus

• US 7,113,270 B2
• Filed: 06/18/2004
• Issued: 09/26/2006
• Est. Priority Date: 06/18/2004
• Status: Active Grant

• Current Assignee: ESPI
• Original Assignee: Electronics Learning Products Incorporated
• Inventors: Buermann, Dale H., Mandella, Michael J.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): ALSOMIRI, ISAM A
• Application Number:
  US10/871,496
• Publication Number:
  US 20050280804A1
• Time in Patent Office: 830 Days
• Field of Search: 356/138, 356/139.1, 356/139.03, 356/153, 356/623, 250/559.29, 250/559.31, 178 1809- 19
• US Class Current: 356/139.03
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of 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

Abstract

An elongate object optically determines at least one of its orientation parameters relative to a plane surface. A probe radiation beam is directed from the object at various angles σ to various locations on the plane, where the angle σ is a periodic function of time. Two angularly-selective radiation detectors oriented at fixed angles τ₁ and τ₂ sense scattered portions of the beam from two locations at two corresponding times. The orientation parameter is computed from a time difference Δt=t₂−t₁ between the two times.

Claims

1. A method for determining at least one orientation parameter of an elongate object having a tip contacting a plane surface, the method comprising:

a) illuminating the plane surface with a probe radiation beam emitted from the elongate object at an angle σ

relative to an axis of the elongate object;

b) varying the angle σ

in accordance with a predetermined pattern so that the probe radiation beam illuminates various locations on the plane surface at various corresponding times;

c) detecting at the elongate object at a first time t₁ a first scattered portion of the probe radiation beam returning from a first illuminated location along a path having a first predetermined angle τ

₁ relative to the axis;

d) detecting at the elongate object at a second time t₂ a second scattered portion of the probe radiation beam returning from a second illuminated location along a path having a second predetermined angle τ

₂ relative to the axis;

e) deriving the orientation parameter from a time difference Δ

t=t₂−

t₁ between detecting the first scattered portion and the second scattered portion.

2. The method of claim 1, wherein the predetermined pattern is a continuous scan pattern.

3. The method of claim 2, wherein the continuous scan pattern is a uniaxial scan pattern.

4. The method of claim 3, wherein the uniaxial scan pattern varies sinusoidally with respect to time, and wherein the first and second illuminated locations are illuminated during a substantially linear region of variation of the uniaxial scan pattern.

5. The method of claim 2, wherein the continuous scan pattern is a biaxial scan pattern.

6. The method of claim 1, wherein the at least one orientation parameter comprises an Euler angle of the elongate object.

7. The method of claim 6, wherein the Euler angle is the second Euler angle θ

.

8. The method of claim 1, wherein the plane surface comprises a jotting surface.

9. The method of claim 8, wherein the jotting surface is selected from the group consisting of a screen, a display, a pad, and a paper surface.

10. The method of claim 1, wherein the elongate object is selected from the group consisting of jotting implements, pointers, robotic arms, and canes.

11. The method of claim 10, wherein the jotting implements are selected from the group consisting of pens, pencils, and styluses.

12. An apparatus for determining at least one orientation parameter of an elongate object having a tip contacting a plane surface, the apparatus comprising:

a) a beam source for emitting a probe radiation beam from the elongate object to illuminate the plane surface;

b) a beam direction controller for directing the probe radiation beam from the elongate object at various angles σ

relative to an axis of the elongate object to various locations on the plane, wherein the various angles σ

are in accordance with a predetermined pattern;

c) a first angularly-selective radiation detector for sensing at a first time t₁ a first scattered portion of the probe radiation beam returning from a first location on the plane surface to the elongate object along a first path having a first angle τ

₁ relative to the axis;

d) a second angularly-selective radiation detector for sensing at a second time t₂ a second scattered portion of the probe radiation beam returning from a second location on the plane surface to the elongate object along a second path having a second angle τ

₂ relative to the axis;

e) a computing unit for deriving the orientation parameter from a time difference Δ

t=t₂−

t₁ between sensing the first scattered portion and sensing the second scattered portion.

13. The apparatus of claim 12, wherein the beam direction controller comprises a beam scanner selected from the group consisting of uniaxial scanners and biaxial scanners.

14. The apparatus of claim 12, wherein the beam source comprises a laser.

15. The apparatus of claim 12, wherein the angularly-selective detector comprises an angular gating optic.

16. The apparatus of claim 15, wherein the angular gating optic comprises at least one element selected from the group consisting of apertures, holographic elements, diffractive elements, refractive elements and reflective elements.

17. The apparatus of claim 12, wherein the computing unit comprises a timing circuit and a look-up table.