Fixture for shape-sensing optical fiber in a kinematic chain

• US 7,815,376 B2
• Filed: 06/30/2008
• Issued: 10/19/2010
• Est. Priority Date: 06/30/2008
• Status: Active Grant

• Current Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Original Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Inventors: Prisco, Giuseppe, Rogers, Theodore W.
• Primary Examiner(s): Peng; Charlie
• Assistant Examiner(s): Radkowski; Peter
• Application Number:
  US12/164,297
• Publication Number:
  US 20090324160A1
• Time in Patent Office: 841 Days
• Field of Search: 385/53, 385/88, 385/90, 385/95, 385/97, 385/98
• US Class Current: 385/66
• CPC Class Codes: A61B 2034/2061 using shape-sensors, e.g. fiber shape sensors with Bragg gratings
• CPC Class Codes: A61B 34/30 Surgical robots
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: G01B 11/165 by means of a grating deformed by the object
• CPC Class Codes: G01D 11/245 Housings for sensors
• CPC Class Codes: G01D 5/35303 using a reference fibre, e.g. interferometric devices
• CPC Class Codes: G01D 5/35316 using a Bragg gratings
• CPC Class Codes: G01D 5/35377 Means for amplifying or modifying the measured quantity
• CPC Class Codes: G01M 11/083 by using an optical fiber in contact with the device under test [DUT]
• CPC Class Codes: G02B 6/022 using mechanical stress, e.g. tuning by compression or elongation, special geometrical shapes such as "dog-bone" or taper G02B6/02204 takes precedence; optical modulation using photo-elastic effect G02F1/0131
• CPC Class Codes: G02B 6/3616 Holders, macro size fixtures for mechanically holding or positioning fibres, e.g. on an optical bench supporting carriers of a microbench type G02B6/3648; micromanipulators B25J7/00; cassettes, bobbins G02B6/4439
• CPC Class Codes: G02B 6/3644 the coupling means being through-holes or wall apertures
• CPC Class Codes: G02B 6/38 having fibre to fibre mating means
• CPC Class Codes: Y10T 29/49826 Assembling or joining
• CPC Class Codes: Y10T 29/49838 by stringing
• CPC Class Codes: Y10T 29/49947 by applying separate fastener

Abstract

Localized strain is effectively eliminated in a shape sensing optical fiber where the fiber exits a link in a kinematic chain. In one aspect, the fiber is positioned in a channel within a fiber fixture portion of the link, and a surface of a lip of the channel is curved. The curved surface of the lip begins tangent to a wall of the channel and has a maximum radius of curvature that is less than the minimum bend radius that the fiber will experience during shape sensing. In another aspect the fiber is positioned within a shape memory alloy tube that extends from the link.

Claims

1. An apparatus comprising:

a first link, a second link, and a joint that couples the first and second links;

an optical fiber extending between the first link and the second link, wherein a limit range of motion of the joint defines a minimum bend radius of the optical fiber; and

a fixture by which the optical fiber is constrained with reference to the first link, wherein the fixture comprises a channel defined therein in which the fiber is positioned to place a length of fiber containing fiber Bragg gratings adjacent a lip of the channel where the channel opens out of the fixture, wherein a curve of a surface of the lip begins effectively tangent to a wall of the channel, and wherein the radius of curvature of the surface of the lip that substantially intersects a bending plane of the fiber as the joint moves is effectively less than the defined minimum bend radius of the optical fiber.

2. The apparatus of claim 1 further comprising:

a strain interrogator;

wherein the strain interrogator receives strain information from the fiber Bragg gratings.

3. The apparatus of claim 1:

wherein the optical fiber extends out of the first link at the longitudinal centerline of the first link.

4. The apparatus of claim 1:

wherein the optical fiber extends out of the first link offset from the longitudinal centerline of the first link.

5. The apparatus of claim 1:

wherein the fixture comprises a first piece and a second piece positioned within the first piece; and

wherein the channel defined in the fixture is defined in the second piece.

6. The apparatus of claim 1 further comprising:

a flexible tube surrounding the optical fiber.

7. The apparatus of claim 1:

wherein the channel comprises a slit having a width that is approximately equal to the diameter of the fiber.

8. The apparatus of claim 1:

wherein the channel comprises a cylinder that permits the fiber to slide longitudinally with reference to the first link.

9. The apparatus of claim 1:

wherein the channel comprises a cylinder that permits the fiber to roll or twist with reference to the first link.

10. The apparatus of claim 1:

wherein the fixture comprises a collet having the channel and the lip defined therein.

11. The apparatus of claim 1:

wherein the first and second links are links in a surgical instrument.

24. The apparatus of claim 6:

wherein the flexible tube surrounding the optical fiber comprises a shape memory alloy.

25. The apparatus of claim 24:

wherein the shape memory alloy comprises a Nickel/Titanium alloy.

12. A method comprising:

assembling a first link, a second link, and a joint that couples the first and second links;

extending an optical fiber between the first link and the second link, wherein a limit range of motion of the joint defines a minimum bend radius of the optical fiber; and

constraining the optical fiber with reference to the first link, wherein the optical fiber is positioned in a constraining channel to place a length of fiber containing fiber Bragg gratings adjacent a lip of the channel, wherein a curve of a surface of the lip begins effectively tangent to a wall of the channel, and wherein the radius of the curve of surface of the lip that substantially intersects a bending plane of the fiber as the joint moves is effectively less than the defined minimum bend radius of the optical fiber.

13. The method of claim 12 further comprising:

interrogating the fiber Bragg gratings for strain information.

14. The method of claim 12:

wherein the optical fiber extends out of the first link at the longitudinal centerline of the first link.

15. The method of claim 12:

wherein the optical fiber extends out of the first link offset from the longitudinal centerline of the first link.

16. The method of claim 12:

wherein constraining the optical fiber comprises positioning a second piece within a first piece and positioning the fiber within the second piece; and

wherein the channel is defined in the second piece.

17. The method of claim 12 further comprising:

wherein the channel comprises a slit having a width that is approximately equal to the diameter of the fiber.

18. The method of claim 12:

wherein constraining the optical fiber comprises permitting the fiber to slide longitudinally with reference to the first link.

19. The method of claim 12:

wherein constraining the optical fiber comprises permitting the fiber to roll or twist with reference to the first link.

20. The method of claim 12 further comprising:

configuring a collet with the constraining channel and the lip.

21. The method of claim 12 further comprising:

positioning a flexible tube around a length of the optical fiber.

22. The method of claim 12:

wherein the first and second links are links in a surgical instrument.

23. The method of claim 12:

wherein constraining the optical fiber comprises allowing the optical fiber to slide longitudinally with reference to the first link.

26. The method of claim 21:

wherein positioning a flexible tube around a length of the optical fiber comprises positioning a shape memory alloy tube around a length of the optical fiber.

27. The method of claim 26:

wherein the shape memory alloy comprises a Nickel/Titanium alloy.