FORCE SENSING APPARATUS AND ROBOT ARM INCLUDING THE SAME

• US 20130104672A1
• Filed: 04/20/2012
• Published: 05/02/2013
• Est. Priority Date: 10/31/2011
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Jun-hyung, Kim, Yeon-ho, Park, Chang-bae, Choi, Hyun--do
• Granted Patent: US 9,186,797 B2
• Time in Patent Office: Days
• US Class Current: 73/862.624
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 34/30 Surgical robots
• CPC Class Codes: B25J 13/085 Force or torque sensors B25J13/082, B25J13/084 take precedence
• CPC Class Codes: G01L 1/246 using integrated gratings, e.g. Bragg gratings
• CPC Class Codes: G01L 5/166 using photoelectric means

Abstract

A multi-axis force sensing apparatus that is installed at an operational end of a surgery robot and is capable of measuring force acting upon the operational end and a robot arm including the force sensing apparatus includes a body that is elastically deformable and has a pipe form extending along an axial direction of the body, an optical fiber strain gauge attached to a surface of the body to measure a tension and compression of the body in at least three directions. The optical fiber strain gauge may include at least three fiber Bragg gratings (FBGs) that are attached to the surface of the body and extended in an axial direction of the body, a light source providing light to each of the FBGs, and a light detector detecting light reflected by the FBGs or light that has passed through the FBGs.

Claims

1. A force sensing apparatus comprising:

a body that is elastically deformable and has a pipe form extending along an axial direction of the body;

at least three fiber Bragg gratings (FBGs) attached to a surface of the body;

a light source providing light to each of the FBGs; and

a light detector detecting light reflected by each of the FBGs or light that has passed through each of the FBGs.

2. The force sensing apparatus of claim 1, wherein the at least three FBGs are arranged to extend along the axial direction of the body.

3. The force sensing apparatus of claim 1, wherein the at least three FBGs are attached to the surface of the body at at least three different positions at predetermined intervals along an azimuth angle direction.

4. The force sensing apparatus of claim 1, wherein the FBGs are attached to an external surface or an inner surface of the body.

5. The force sensing apparatus of claim 1, further comprising at least three openings that are formed in the body between each two adjacent FBGs.

6. The force sensing apparatus of claim 5, wherein the body is formed of a plastic material.

7. The force sensing apparatus of claim 5, further comprising a plurality of bolt holes respectively formed in an upper portion and a lower portion of the body,

wherein an extension line between a center of the bolt holes and a center of the openings is formed at a 45 degree angle with respect to a horizontal surface.

8. The force sensing apparatus of claim 5, wherein when an operational end of the force sensing apparatus is assumed to be an upper portion of the body, a center of the openings is at a position lower than a center of the FBGs between each two adjacent FBGs.

9. The force sensing apparatus of claim 1, wherein the body comprises:

an upper portion and a lower portion separated from each other;

at least three elastic beams that connect the upper portion and the lower portion of the body and are extended in a direction perpendicular to an axis of the body; and

gaps respectively formed between one of the elastic beams and the upper portion of the body and between one of the elastic beams and the lower portion of the body.

10. The force sensing apparatus of claim 9, wherein the body is formed of a metal.

11. The force sensing apparatus of claim 9, wherein a first end portion of the elastic beam is connected to the upper portion of the body, and a second end portion of the elastic beam disposed opposite to the first end portion is connected to the lower portion of the body.

12. The force sensing apparatus of claim 9, wherein the body further includes at least three stoppers respectively formed between each two adjacent elastic beams.

13. The force sensing apparatus of claim 12, wherein the stopper comprises:

a first protrusion that protrudes and extends from the lower portion of the body toward the upper portion of the body in the axial direction of the body; and

a second protrusion that protrudes and extends from the upper portion of the body toward the lower portion of the body in the axial direction of the body to surround the first protrusion.

14. The force sensing apparatus of claim 13, wherein the first protrusion comprises an intermediate portion having a relatively small width and an end portion having a relatively large width, and the second protrusion comprises an intermediate portion having a relatively small width and an end portion having a relatively large width, wherein the first protrusion and the second protrusion are engaged with each other in a complementary form.

15. The force sensing apparatus of claim 14, wherein the gaps extend between the first protrusion and the second protrusion.

16. The force sensing apparatus of claim 13, wherein the at least three elastic beams and the at least three stoppers are formed in a monolithic manner by forming at least three gaps in the body by using a wire electrical discharge machining (EDM) method, and two end sides of each of the at least three gaps extend in a direction perpendicular to the axial direction of the body, and centers of each of the gaps are curved to form the at least three stoppers.

17. The force sensing apparatus of claim 16, wherein two adjacent gaps are separated in the axial direction of the body and are partially overlapped with each other in an azimuth angle direction, and both side portions of each of the gaps are disposed in parallel to a side portion of another adjacent gap such that the elastic beam is formed between the two adjacent gaps.

18. The force sensing apparatus of claim 16, wherein the body further comprises an opening formed at each of two end portions of each of the gaps.

19. The force sensing apparatus of claim 12, wherein the FBGs are attached to the body across the stoppers.

20. The force sensing apparatus of claim 12, wherein the FBGs are attached to the body across the elastic beam.

21. A robot arm comprising a force sensing apparatus according to claim 1.

22. The robot arm of claim 21, wherein the body of the force sensing apparatus is the same with a body of the robot arm.

23. The robot arm of claim 21, further comprising grippers installed at an operational end of the body.

24. A method to sense a force applied to an elastically deformable body, the method comprising:

attaching at least three optical fiber strain gauges to the elastically deformable body;

providing light to each of the at least three optical fiber strain gauges;

detecting the light from each of the at least three optical fiber strain gauges; and

calculating the force applied to the deformable body based on the detected light.