Force torque sensor, force torque sensor frame, and force torque measurement method

Patent metadata

Field	Value
Publication number	US-9448128-B2
Application number	US-201314399002-A
Country	US
Kind code	B2
Filing date	May 10, 2013
Priority date	May 10, 2012
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

The present invention relates to a force torque sensor, a force torque sensor frame, and a force torque measurement method. The force torque sensor includes a central hub, a plurality of beams each having one side connected to the hub, and a rim connected to the other side of each beam to surround the hub and the plurality of beams. The force torque measurement method includes: a step of forming a gradient shape in a longitudinal direction thereof so that a section is provided in which a strain rate on each of the beams due to a force or torque is maintained within a predetermined value; and a step of measuring a strain rate in X-axis, Y-axis, or Z-axis directions after a strain gauge is attached to a corresponding section. Thus, a measurement center of the strain gauge may be positioned within a predetermined section.

First claim

What is claimed is:

1. A force torque sensor comprising:
a central hub;
a plurality of beams, each beam of the plurality of beams having a first end connected to the hub and a gradient shape in a longitudinal direction thereof;
a strain gauge attached to one beam of the plurality of beams, the strain gauge being configured to measure a strain rate of the beam to which the strain gauge is attached; and
a rim connected to a second end of each beam of the plurality of beams such that the rim surrounds the hub and the plurality of beams,
wherein each beam of the plurality of beams has at least one curved sidewall extending between the hub and the rim, and the gradient shape comprises a convex portion of the at least one curved sidewall.

2. The force torque sensor of claim 1 ,
wherein the beam has a section in which a strain rate due to a force or torque along the gradient shape is maintained below a certain value, and
wherein the strain gauge is attached to the section.

3. The force torque sensor of claim 2 , wherein the section has a length of 1.5 mm to 2.0 mm in the longitudinal direction of the beam.

4. The force torque sensor of claim 2 , wherein the section has a difference between a maximum value and a minimum value of the strain rate within 20 um/m or less.

5. The force torque sensor of claim 2 , wherein the strain gauge is attached such that a measurement center thereof is positioned within the section.

6. The force torque sensor of claim 1 , wherein the strain gauge measures a strain rate due to a force or torque in a direction of an X axis, a Y axis, or a Z-axis.

7. The force torque sensor of claim 1 , wherein the strain gauge comprises a plurality of gauges positioned on opposing surfaces of the beam to which the strain gauge is attached, the gauges of the plurality of gauges being arranged opposite to each other with respect to the beam in order to measure a strain rate in a single axis direction.

8. The force torque sensor of claim 1 , wherein the strain gauge is a first strain gauge, and the force torque sensor further comprises:
a second strain gauge attached to the beam to which the first strain gauge is attached;
a third strain gauge attached to a second beam of the plurality of beams; and
a fourth strain gauge attached to the second beam of the plurality of beams,
wherein the first strain gauge and the second strain gauge are positioned opposite to each other with respect to the one beam of the plurality of beams, the third strain gauge and the fourth strain gauge are positioned opposite to each other with respect to the second beam of the plurality of beams, and the strain rate due to the force or torque in the single axis direction is measured using the first strain gauge, the second strain gauge, the third strain gauge, and the fourth strain gauge.

9. The force torque sensor of claim 1 , wherein the plurality of beams are positioned symmetrically with respect to the hub.

10. The force torque sensor of claim 1 , wherein a quantity of beams of the plurality of beams is four, and the four beams are arranged as a cross centered on the hub.

11. The force torque sensor of claim 1 , wherein the hub, the one beam, or the rim comprises iron steel, nickel-chromium-molybdenum steel, stainless steel, tool steel, hardened stainless steel, an aluminum alloy, or duralumin.

12. A force torque sensor frame comprising:
a central hub;
a plurality of beams, each beam of the plurality of beams having a first end connected to the hub, a gradient shape in a longitudinal direction thereof, and a strain gauge attached thereon; and
a rim connected to a second end of each beam of the plurality of beams such that the rim surrounds the hub and the plurality of beams,
wherein each beam of the plurality of beams has at least one curved sidewall extending between the hub and the rim, and the gradient shape comprises a convex portion of the at least one curved sidewall.

13. The force torque sensor frame of claim 11 , wherein the beam has a section in which a strain rate due to a force or torque along the gradient shape is maintained below a certain value, and the strain gauge is attached to the section.

14. The force torque sensor frame of claim 11 , wherein the hub, the beam, or the rim comprises iron steel, nickel-chromium-molybdenum steel, stainless steel, tool steel, hardened stainless steel, an aluminum alloy, or duralumin.

15. A force torque measurement method using a force torque sensor including a central hub; a plurality of beams, each beam of the plurality of beams having a first end connected to the hub, and a rim connected to a second end of each beam of the plurality of beams such that the rim surrounds the hub and the plurality of beams, the force torque measurement method comprising:
a processing step of forming a gradient shape in a longitudinal direction thereof such that each beam of the plurality of beams has a section in which a strain rate due to a force or torque is maintained below a certain value;
an attachment step of attaching a strain gauge to the section; and
a measurement step of measuring the strain rate in a direction of an X axis, a Y-axis, or a z-axis using the attached strain gauge,
wherein each beam of the plurality of beams has at least one curved sidewall extending between the hub and the rim, and the gradient shape comprises a convex portion of the at least one curved sidewall.

Assignees

• Korea Electronics Technology

Inventors

• Kim Bongseok
• Hwang Junghoon
• Park Changwoo
• Kim Taekeun
• Choi Seungyun

Classifications

• G01L5/161

  using variations in ohmic resistance · CPC title

• G01L3/1457

  involving resistance strain gauges · CPC title

• G01L5/16

  for measuring several components of force · CPC title

• G01L1/22 Primary

  using resistance strain gauges · CPC title

• G01L3/108

  involving resistance strain gauges · CPC title