Topological and motion measuring tool

• US 20020088931A1
• Filed: 01/11/2001
• Published: 07/11/2002
• Est. Priority Date: 01/11/2001
• Status: Active Grant

• Current Assignee: Canadian Space Agency (Government of Canada)
• Original Assignee: Canadian Space Agency (Government of Canada)
• Inventors: Danisch, Lee Allan, Lutes, Jordan Patrick, Danisch, Jonathan Freeman
• Granted Patent: US 6,563,107 B2
• Time in Patent Office: Days
• US Class Current: 250/227.14
• CPC Class Codes: A61B 1/009 with bending or curvature detection of the insertion part
• CPC Class Codes: D04B 1/12 characterised by thread material
• CPC Class Codes: D07B 1/145 comprising elements for indicating or detecting the rope or cable status
• CPC Class Codes: D10B 2401/20 optical
• CPC Class Codes: D10B 2403/02431 with electronic components, e.g. sensors or switches
• CPC Class Codes: G01B 11/18 using photoelastic elements
• CPC Class Codes: G01D 5/268 using optical fibres G01D5/28 - G01D5/38 take precedence
• CPC Class Codes: G01D 5/35383 using multiple sensor devices using multiplexing techniques

Abstract

A measuring device for providing data corresponding to a geometric configuration in space, in the form of a flexible, compliant, measurement member capable of bending in at least one degree of freedom and extending along a medial axis or plane. The member has spaced flexure sensors distributed at known locations on the member and separated by known sensor spacing intervals to provide flexure signals indicating the local state of flexure present at the locations. The member comprises a multiplicity of formed, i.e. shaped, fibers, these fibers including sensing fibers having sensing portions which provide the flexure sensors, the sensing portions of different fibers being located at differing distances along the member so as to be located at the sensor spacing intervals, the formed fibers being in mutually supporting relationship, as by continuous or repeated contact with each other. Such fibers may constitute most or all of the member.

Claims

1. A measuring device for providing data corresponding to a geometric configuration in space, said device being in the form of a flexible, compliant, measurement member capable of bending in at least one degree of freedom, said member extending along a medial axis or plane and having spaced flexure sensors distributed at sensing locales having known locations on said member and separated by known sensor spacing intervals to provide flexure signals indicating the local state of flexure present at said locations;

wherein;

(1) the measurement member comprises a multiplicity of formed fibers,

(2) such fibers being generally non-straight when the medial axis or plane of the member is respectively straight or flat,

(3) said formed fibers including sensing fibers having sensing portions which provide said flexure sensors,

(4) the sensing portions of different fibers being located at differing distances along said member so as to be located at said sensing locales spaced at said sensor spacing intervals,

(5) the overall form of the measurement member being maintained substantially by the form of the constituent fibers, alone or by their continuous or repeated contact with each other, to provide the strength or stability of the member.

2. A measuring device according to claim 1, wherein said formed fibers are mutually supporting by virtue of each fiber having continuous or repeated connections to others of said fibers along the length of the fiber.

3. A measuring device according to claim 1, wherein at least most of said formed fibers extend substantially the full length of the member.

4. A measuring device according to claim 1, wherein at least some of said sensing fibers extend substantially the full length of the member.

5. A measuring device according to claim 4, wherein substantially all said sensing fibers extend the full length of the member.

6. A measuring device according to claim 1, wherein only some of said formed fibers extend the full length of the member, said member being tapered.

7. A measuring device according to claim 1, wherein the stiffness of the member is not substantially greater than the total stiffness of said formed fibers.

8. A measuring device according to claim 1, wherein said formed fibers provide a major part of the tensile strength of the member.

9. A measuring device according to claim 1, wherein said member is substantially wholly constituted of said formed fibers, and wherein said fibers are optical fibers including said sensing fibers and other optical fibers used as reference fibers or illuminating fibers or light return fibers.

10. A measuring device according to claim 1 wherein said formed fibers are optical fibers and the sensing portions of the fibers are loss zones which are sensitive to their state of curvature by virtue of areas of their outer surfaces having been made absorbent to light passing along such fibers.

11. A measuring device according to claim 1, wherein said formed fibers are electrical conductors having axial zones the resistance of which is modulated by bending and twisting of said member.

12. A measuring device according to claim 1, wherein said formed fibers are electrical conductors electrically shielded from each other except in axial zones where capacitive coupling is enabled between chosen adjacent fibers, wherein the coupling is modulated by bending and twisting of said member

13. A measuring device according to claim 10, wherein said formed optical fibers include fibers which maintain a non-straight form by reason of heat treatment or the like.

14. A measuring device according to claim 1, wherein said member is formed as a cyclical structure made up of said formed fibers, which fibers provide said member with sensing locales distributed in a repeating pattern along said member.

15. A measuring device according to claim 1, wherein at least some of said sensing portions of the fibers are obliquely orientated to said medial axis or plane, whereby said member has sensing portions responsive to twisting of the member as well as sensing portions responsive to bending of the member.

16. A measuring device according to claim 1, wherein said measurement member is formed to have cyclically repeating sinuations, which sinuations provide extensibility which is measured by the sensing fibers as a consequence of their measurement of position and orientation along the length of the member.

17. A measuring device according to claim 14, wherein said fibers have cyclically repeating curves that take on cyclically repeating pairs of opposed deformations locally within each curve during curvature of the measuring device, without substantial changes in the net extension or compression of the fibers along the full extent of the device whereby said curvature can occur without overall slippage of fibers along their full length.

18. A measuring device according to claim 10 wherein said fibers have cyclically repeating curves and said loss zones placed thereupon are effective to modulate light throughput with curvature of the device, wherein the form of the repeating curves produces a desired circumferential orientation and axial placement of light loss with respect to the device, such that the loss geometry produces modulation of the light indicative of the position and orientation of the device.

19. A measuring device according to claim 18 wherein the enhanced losses occur in only an axial portion or portions of one of said loss zones that would lose light uniformly along the entire loss zone when the fiber is straight and unformed.

20. A measuring device according to claim 19 wherein the said one loss zone is a thin axial band on a fiber when it is straight and unformed.

21. A measuring device according to claim 18 wherein said one of said loss zone is a circumferential band on a fiber when it is straight and unformed.

22. A measuring device according to claim 19 wherein the majority of the loss of a given fiber occurs at the same circumferential orientation at repeating intervals along the device, with the same spatial frequency as that of the cyclically repeating curves, wherein the repeating loss zones are used to create a spatially distributed sensing zone to capture an average reading of bend and twist along said zone.

23. A measuring device according to claim 14, wherein the member is in the form of a rope largely made up of said formed fibers, which formed fibers are helical and provide strands of said rope.

24. A measuring device according to claim 23, wherein said fibers are wound around a central core which provides part of the tensile strength of the member.

25. A measuring device according to claim 23, wherein at least one portion of the rope is provided with enhanced twist which is greater than the twist of parts of the rope between said portions.

26. A measuring device according to claim 25, wherein the portion with enhanced twist occupies an axial distance equal to the length occupied by one complete turn of the helical form of any one fiber within the portion having enhanced twist, or an integer multiple of said length.

27. A measuring device according to claim 1, wherein said fibers include a first set of fibers helically wound in one direction and a set of fibers helically wound in the opposite direction, the fibers of the two sets being interwoven with each other, so that said member is in the form of a braided structure.

28. A measuring device as in claim 1 wherein the member is in the form of a ribbon having a longitudinal dimension, said formed fibers including sinuous fibers connected side-by-side in the plane of the ribbon, the member being substantially limited to bending along its length only about axes which lie in the plane of the ribbon and which are transverse to the longitudinal dimension of the member, while the member is also free to twist.

29. A measuring device comprised of multiple ribbons according to claim 28 wherein the constituent ribbons are interleaved on alternate wavelengths of their sinuations.

30. A measuring device according to claim 28, wherein said ribbon is wound into helical form.

31. A measuring device according to claim 1, wherein said sensor is wound or sinuated in known relationship to features on a body to be measured, wherein the mathematical model of the turns and sinuations of the sensor is used to locate and scale similar features upon a mathematical model of the body being measured.

32. A measuring device according to claim 14, wherein the member is in the form of a woven or knitted fabric largely made up of said formed fibers.

33. A measuring device according to claim 32, wherein said member is in the form of a flexible sheet made up of a first set of said formed fibers extending in a first direction and a second set of said formed fibers extending across said fibers of the first set and being interwoven or interlaced with the fibers of the first set.

34. A measuring device according to claim 33, wherein the member is in the form of a woven sheet formed with a warp of said fibers of the first set and a weft of said fibers of the second set.

35. A measuring device according to claim 33, wherein the member is in the form of a knitted sheet formed from said formed fibers.

36. A measuring device according to claim 1, wherein each formed fiber has only one of said sensing portions.

37. A measuring device according to claim 1 wherein said fibers are optical fibers having reversing loops and wherein the fibers are sensitive to their state of curvature in the region of the loops.

38. A measuring tool for providing data corresponding to a geometric configuration in space comprising:

(1) a flexible, compliant, measurement member extending along a medial axis or plane and capable of bending in at least one degree of freedom, said member having spaced flexure sensors at known locations distributed on said member and separated by flexure sensor spacing intervals to provide flexure signals indicating the local state of flexure present at said locations;

(2) sensor data processing means coupled to the flexure sensors for receiving flexure signals therefrom and for presenting data on the geometric configuration of the member in three dimensional space, said data processing means operating by interpolating or extrapolating the geometric configuration of the member from the flexure signals provided by the flexure sensors and the spacings intervals between such sensors;

wherein the measurement member comprises a multiplicity of formed fibers, such fibers being non-straight when the medial axis or plane of the member is respectively straight or flat, said formed fibers including sensing fibers having sensing portions which provide said flexure sensors, the sensing portions of different fibers being located at differing distances along said fibers so as to be located at said sensor spacing intervals, said formed fibers being in mutually supporting relationship, as by continuous or repeated contact with each other, so as to contribute materially to the strength or stability of the member, the overall form of the measurement member being maintained substantially by the form of the constituent fibers, alone or by their continuous or repeated contact with each other, to provide the strength or stability of the member.