US-12618725-B2 - Elastic body including deformable portions and force sensor using the same

US12618725B2US 12618725 B2US12618725 B2US 12618725B2US-12618725-B2

Abstract

A force sensor includes a first structure, a second structure, a plurality of third structures and a plurality of strain sensors. The first structure includes three or more first elastic portions deformable in six axial directions. The second structure includes three or more second elastic portions deformable in the six axial directions, and three or more relay portions connected to the second elastic portions, respectively, and deformable in the six axial directions. A plurality of third structures are provided respectively between each of the relay portions of the second structure and each of the first elastic portions of the first structure. The plurality of strain sensors are provided between the first structure and each of the relay portions.

Inventors

Takayuki Endo
Takashi Suzuki

Assignees

NIDEC COPAL ELECTRONICS CORPORATION

Dates

Publication Date: 20260505
Application Date: 20210527
Priority Date: 20190128

Claims (14)

1 . A force sensor comprising: a first structure mounted on a mounting plate and including three or more pairs of first elastic portions disposed therearound; three or more second structures mounted on a main body, the three or more second structures being arranged around the first structure at equal intervals and in correspondence with each pair of first elastic portions, each of the second structures including two second elastic portions and a relay portion connected between the two second elastic portions; two third structures arranged in correspondence with each one of the second structures, each third structure being connected between the relay portion of the corresponding second structure and one of the pairs of first elastic portions corresponding to the second structure, three or more strain sensors, one end of each of the three or more strain sensors being coupled between the first structure located between each of the pairs of first elastic portions, and another end of each of the three or more strain sensors being coupled to the relay portion of the corresponding second structure, and a plurality of fixing members each fixing one end of each of the strain sensors to the first structure and fixing another end of each of the strain sensors to the relay portion of each of the second structures.
2 . The force sensor of claim 1 , wherein the second structure has a ring-like outer shape.
3 . The force sensor of claim 1 , wherein the relay portion is provided along a direction intersecting a longitudinal direction of the respective one of the third structures.
4 . The force sensor of claim 1 , wherein each of the first elastic portions of the first structure is provided along a direction intersecting a longitudinal direction of the respective one of the third structures.
5 . The force sensor of claim 1 , wherein the third structures, the first elastic portions and the at least one second elastic portion have a same thickness, and a width of the third structures, the first elastic portions and the at least one second elastic portion is less than the thickness.
6 . The force sensor of claim 1 , wherein one of the first elastic portions is connected to one of the third structures.
7 . The force sensor of claim 1 , wherein one of the first elastic portions is connected to at least two of the third structures.
8 . The force sensor of claim 1 , wherein the at least one second elastic portion has a U-shape, and the relay portion is provided between the two second elastic portions.
9 . The force sensor of claim 1 , wherein the strain sensors each comprises a strain body and a plurality of strain gauges provided on the strain body.
10 . The force sensor of claim 9 , wherein the plurality of strain sensors each comprises a strain body provided with a plurality of strain gauges, and a thickness of the strain body is less than thicknesses of the first structures, the second structure, and the third structures.
11 . The force sensor of claim 1 , wherein each of the strain sensors is located between the two third structures and parallel to the two third structures.
12 . The force sensor of claim 1 , further comprising a cover fixed to the mounting plate.
13 . The force sensor of claim 1 , wherein one end of each strain sensor of the three or more strain sensors is fixed to the first structure between the one of the corresponding pairs of first elastic portions by the fixing member, and another end of each of strain sensor of the three or more strain sensors is fixed to the relay portion of the corresponding second structure by the fixing member.
14 . The force sensor of claim 1 , wherein the mounting plate is provided as a movable body operable on the main body, and the three or more strain sensors output electric signals when the pairs of first elastic portions, the two second elastic portions, the two third structures, the relay portions, and the three or more strain sensors are deformed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation application of PCT Application No. PCT/JP2019/047064, filed Dec. 2, 2019 and based upon and claiming the benefit of priority from prior Japanese Patent Application No. 2019-012322, filed Jan. 28, 2019, the entire contents of all of which are incorporated herein by reference. FIELD The present disclosure relates to an elastic body used for, for example, robot arms and the like, and a force sensor using the same. BACKGROUND Force sensors are used, for example, by robot arms and the like, and they detect a force (Fx, Fy, Fz) and a moment (Mx, My, Mz) with respect to three axes (x, y and z) orthogonal to each other (see, for example, Patent Literature 1 (JP 2018-48915 A)). SUMMARY A force sensor comprises an elastic body deformable along six axial directions, for example, three axial directions and along three circumferential directions around the three respective axial directions, and a plurality of strain sensors are provided on the elastic body. Each of the strain sensors comprises a strain body and a plurality of strain gauge provided on the strain body. Further, the force sensor comprises a stopper to protect the elastic body and the strain body from an external force. When the rigidity of the elastic body and strain body (which may be combined together and referred to as a sensor body) is high and the amount of displacement among six axial directions is very small, the structure of the stopper needs to be processed at high accuracy, making it difficult to implement the stopper. When the rigidity of the sensor body greatly differs from one axial direction to another, the designing of the stopper is complicated, making it difficult to implement the stopper. On the other hand, when designing the sensor body without providing a stopper, it is difficult to increase the displacement of the elastic body and the strain body, and therefore a high sensor output cannot be obtained. As a result, the sensor thus obtained is vulnerable to an outer disturbance such as noise, and its measurement accuracy is low. Embodiments of the present disclosure described herein aim to provide an elastic body with which a sufficient sensor output can be obtained and the measurement accuracy can be improved, and a force sensor using the same. According to one embodiment, an elastic body comprises a first structure including three or more first elastic portions deformable in six axial directions, a second structure including three or more second elastic portions deformable in the six axial directions and three or more relay portions respectively connected to the second elastic portions, deformable in the six axial directions, and a plurality of third structures each provided between each respective one of the relay portions of the second structure and each respective one of the first elastic portions of the first structure. According to another embodiment, a force sensor comprises a first structure including three or more first elastic portions deformable in six axial directions, a second structure including three or more second elastic portions deformable in the six axial directions and three or more relay portions respectively connected to the second elastic portions, deformable in the six axial directions, a plurality of third structures each provided between each respective one of the relay portions of the second structure and each respective one of the first elastic portions of the first structure, and a plurality of strain sensors provided between the first structure and each of the relay portions. Additional objects and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages of the disclosure may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the disclosure. FIG. 1 is a perspective diagram showing a force sensor according to an embodiment. FIG. 2 is a decomposed perspective diagram showing the force sensor shown in FIG. 1. FIG. 3 is a perspective view showing the force sensor shown in FIG. 2 when partially assembled. FIG. 4 is a perspective view showing the force sensor shown in FIG. 2 when further assembled. FIG. 5 is a further decomposed perspective diagram showing the force sensor shown in FIG. 2. FIG. 6 is a plan view showing an elastic body according to this embodiment when taken out. FIG. 7 is a schematic representation of the elastic body of this embodiment. FIG. 8 is a partial plan view showing an example of the elastic body shown in FIG. 6