Strain sensor fixing device and torque sensor using the same

Abstract

The present application provides a strain sensor fixing device that prevents a decrease in sensor performance and a large increase in device size, and reliably fixes a strain sensor to a structure, and a torque sensor using the device. A fixing member (41) has a protrusion (41a) at a first end portion that contacts a first structure (11), and a second end portion that can contact a first end portion of a strain generator (19-1) provided on the first structure (11). A screw (42) is inserted into the first structure (11) and screwed between the first end portion and the second end portion of the fixing member (41).

Description

[0001] This application is a divisional application of the application with the application number 201980016931.1 and the title "Fixing device of strain sensor and torque sensor using the fixing device" filed on February 14, 2019. TECHNICAL FIELD

[0002] Embodiments of the present application relate to a fixing device of a strain sensor provided at a joint of a robot arm, for example, and a torque sensor using the fixing device. BACKGROUND

[0003] A torque sensor has a first structure to which a torque is applied, a second structure from which a torque is output, and a plurality of strain generating portions as beams connecting the first structure and the second structure, and a plurality of strain gauges as sensor elements are arranged in the strain generating portions. A bridge circuit is configured using the strain gauges (see, for example, Patent Documents 1, 2, and 3).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-096735

[0007] Patent Document 2: Japanese Patent Application Publication No. 2015-049209

[0008] Patent Document 3: Japanese Patent Application Publication No. 2017-172983 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] Generally, a strain sensor has a plurality of strain gauges as sensor elements arranged on a strain generating body made of metal. As a method of fixing the strain sensor to a torque sensor, there are, for example, a method using welding, a method using an adhesive, and a method using a plurality of screws.

[0011] However, in the case where the strain sensor is fixed to the structure by welding, the welding is accompanied by a sharp temperature rise of the strain generating body. Therefore, the composition and shape of the strain generating body and the strain gauges change, which can affect the performance of the strain sensor.

[0012] In addition, in the case where the strain sensor is fixed to the structure using an adhesive, the adhesive having low rigidity is interposed between the strain generating body and the structure. Therefore, the deformation of the structure is not directly transmitted to the strain generating body, which can reduce the sensitivity of the strain sensor.

[0013] On the other hand, in a case where a strain sensor is fixed to a structure using a screw, a pressing member is provided on a strain generator, and the pressing member is fastened to the structure by the screw, whereby the strain generator is fixed to the structure by the pressing member. In this structure, the pressing member and the strain generator are in surface contact, and therefore the pressing member needs to exert a high pressing force on the strain generator. In order to exert a high pressing force, the pressing member needs to be large in size and high in rigidity, and the screw needs to be large in size and the number of screws needs to be increased. Therefore, it is difficult to make the strain sensor small and thin.

[0014] The present embodiment provides a strain sensor fixing device and a torque sensor using the fixing device, which can prevent a decrease in sensor performance and a large size of a device structure, and can reliably fix a strain sensor to a structure.

[0015] Solution to the problem

[0016] The present embodiment provides a strain sensor fixing device including: a fixing member having a first end portion and a second end portion, the second end portion being contactable with a third end portion of a strain generator provided on a first structure; a protrusion provided on one of the first end portion of the fixing member and a portion of the first structure corresponding to the first end portion; and a screw inserted into the first structure and screwed between the first end portion and the second end portion of the fixing member.

[0017] Preferably, the protrusion can have a height higher than a thickness of the strain generator.

[0018] Preferably, the second end portion of the fixing member can have a width wider than a width of the strain generator and can be in line contact with the strain generator.

[0019] The torque sensor of the embodiment includes a first structure, a second structure, a plurality of third structures connecting the first structure and the second structure, a strain generator disposed between the first structure and the second structure, a first fixing device provided to the first structure and fixing a first end portion of the strain generator to the first structure, and a second fixing device provided to the second structure and fixing a second end portion of the strain generator to the second structure. The first fixing device and the second fixing device each include a fixing member having a third end portion and a fourth end portion, the fourth end portion being in contact with the first end portion of the strain generator provided to the first structure or the second end portion of the strain generator provided to the second structure, a protrusion provided to one of the third end portion of the fixing member and a portion of the first structure corresponding to the third end portion or one of the third end portion of the fixing member and a portion of the second structure corresponding to the third end portion, and a screw inserted into the first structure or the second structure and screwed between the third end portion and the fourth end portion of the fixing member.

[0020] Preferably, the protrusion can have a height higher than a thickness of the strain generator.

[0021] Preferably, the fourth end portion of the fixing member can have a width wider than a width of the strain generator and can be in linear contact with the strain generator.

[0022] Effects of the Invention

[0023] The embodiment of the present application can provide a strain sensor fixing device capable of preventing a sensor performance from being degraded and a device structure from being enlarged and reliably fixing a strain sensor to a structure, and a torque sensor using the fixing device. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a plan view showing a torque sensor to which the embodiment is applied.

[0025] Figure 2 is a plan view showing a part of Figure 1 .

[0026] Figure 3 is a plan view showing a part of Figure 2 .

[0027] Figure 4 is a perspective view of Figure 3 .

[0028] Figure 5 is a perspective view of Figure 3A portion of the enlarged plan view indicated by a broken line.

[0029] Figure 6 is a cross-sectional view taken along the line VII-VII of Figure 1 the plan view of a portion B.

[0030] Figure 7 indicates the present embodiment, is a cross-sectional view taken along the line VII-VII of Figure 2

[0031] Figure 8 is a plan view indicating the relationship between the fixed member and the strain generator shown in Figure 7

[0032] Embodiment

[0033] Hereinafter, an embodiment will be described with reference to the drawings. In the drawings, like parts are designated by like reference numerals.

[0034] Figure 1 indicates an example of a torque sensor 10 to which the present embodiment is applied. The structure of the torque sensor 10 is not limited to this, and the present embodiment can be applied to torque sensors of various structures. In addition, the present embodiment can be applied not only to torque sensors but also to force sensors and the like (force sensation sensors) that use strain gauges.

[0035] Figure 1 In the present embodiment, the torque sensor 10 is provided with a first structure 11, a second structure 12, a plurality of third structures 13, a fourth structure 14, a fifth structure 15, stoppers 16, 17, and a cover 18.

[0036] The first structure 11 and the second structure 12 are formed in a ring shape, and the diameter of the second structure 12 is smaller than the diameter of the first structure 11. The second structure 12 is arranged concentrically with the first structure 11, and the first structure 11 and the second structure 12 are connected by a plurality of third structures 13 arranged in a radial shape as beam portions. The second structure 12 has a hollow portion 12a through which, for example, a wiring (not shown) passes.

[0037] The first structure 11 is connected to, for example, a measured body, and the plurality of third structures 13 transmit a torque from the first structure 11 to the second structure 12. Conversely, the second structure 12 can be connected to the measured body, and a torque can be transmitted from the second structure 12 to the first structure 11 via the plurality of third structures 13.

[0038] The first structure 11, the second structure 12, and the plurality of third structures 13 are formed of metal, for example, stainless steel, but a material other than metal can also be used if sufficient mechanical strength can be obtained with respect to an applied torque.

[0039] Figure 2 ​​Indicates demolition Figure 1 The states of the stops 16 and 17. A first strain sensor 19 and a second strain sensor 20 are disposed between the first structure 11 and the second structure 12. That is, as described later, one end of the first strain sensor 19 and the second strain sensor 20 are engaged with the first structure 11, and the other end of the first strain sensor 19 and the second strain sensor 20 are engaged with the second structure 12.

[0040] Furthermore, the first strain sensor 19 and the second strain sensor 20 are positioned symmetrically with respect to the centers (centers of torque application) of the first structure 11 and the second structure 12. In other words, the first strain sensor 19 and the second strain sensor 20 are positioned on the diameter of the annular first structure 11 and the second structure 12.

[0041] The thickness of the first strain sensor 19 and the second strain sensor 20, i.e., the thickness of the strain generator (described later), is thinner than the thickness of the third structure 13. The mechanical strength of the torque sensor 10 is set according to the thickness and width of the third structure 13. Multiple strain gauges, serving as sensor elements, are installed in the strain generator, and these sensor elements are used to form a bridge circuit.

[0042] The baffles 16 and 17 function as waterproof covers to protect the first strain sensor 19 and the second strain sensor 20 from mechanical deformation and to prevent moisture from entering the first strain sensor 19 and the second strain sensor 20. Details of the baffles 16 and 17 will be described later.

[0043] The first strain sensor 19 is connected to the flexible substrate 21, and the second strain sensor 20 is connected to the flexible substrate 22. The flexible substrates 21 and 22 are connected to a printed circuit board (not shown) covered by a cover 18. The printed circuit board contains an operational amplifier or similar device that amplifies the output voltage of the bridging circuit described later. The circuit structure is not essential to this embodiment, therefore, its description is omitted.

[0044] Figure 3 , Figure 4 From Figure 1 , Figure 2 The first strain sensor 19 and the second strain sensor 20, flexible substrates 21 and 22, and cover 18 are removed, indicating that there is only a first structure 11, a second structure 12, multiple third structures 13, a fourth structure 14, and a fifth structure 15.

[0045] The torque sensor 10 is configured such that when a force other than torque (Mz), particularly in the direction of arrow Fz and Mx shown in the figure, is applied to the torque sensor 10, the strain is not concentrated on the multiple strain gauges that are provided as sensor elements on the strain generators of the first strain sensor 19 and the second strain sensor 20.

[0046] Specifically, the fourth structure 14 and the fifth structure 15 are provided at positions symmetrical with respect to the centers of the first structure 11 and the second structure 12, the fourth structure 14 has a recess 14f that is continuous from the first structure 11 to the second structure 12, and the fifth structure 15 has a recess 15f that is continuous from the first structure 11 to the second structure 12. As will be described later, the first strain sensor 19 is arranged in the recess 14f of the fourth structure 14, and the second strain sensor 20 is arranged in the recess 15f of the fifth structure 15.

[0047] Further, Figures 1 to 4 The case where two strain sensors, the first strain sensor 19 and the second strain sensor 20, are provided is described, but the number of strain sensors can be three or more. In this case, the number of structures can be increased in accordance with the number of strain sensors.

[0048] The fourth structure 14 and the fifth structure 15 are the same structure, and therefore, only the fourth structure 14 will be described in detail.

[0049] As shown in FIG. 1, the fourth structure 14 has a first connecting portion 14a and a second connecting portion 14b that are joining portions that join the first strain sensor 19, a third connecting portion 14c and a fourth connecting portion 14d that are beams, and an opening portion 14e that is surrounded by the first connecting portion 14a, the second connecting portion 14b, the third connecting portion 14c, and the fourth connecting portion 14d. Figure 5

[0050] In other words, the fourth structure 14 is a beam having the opening portion 14e that is provided between the first structure 11 and the second structure 12.

[0051] The first connecting portion 14a extends from the first structure 11 to the second structure 12 side. The second connecting portion 14b extends from the second structure 12 to the first structure 11 side.

[0052] The third connecting portion 14c and the fourth connecting portion 14d that are beams are provided between the first connecting portion 14a and the second connecting portion 14b.

[0053] The lengths L1 of the third connecting portion 14c and the fourth connecting portion 14d are shorter than the length L2 of the third structure 13 that is a beam (as shown in FIG. 1). The widths W1 of the third connecting portion 14c and the fourth connecting portion 14d in the torsion direction (Mz) are narrower than the widths W2 of the first connecting portion 14a and the second connecting portion 14b in the torsion direction, and the total of the widths W1 of the third connecting portion 14c and the fourth connecting portion 14d is smaller than the width W3 of the third structure 13 in the torsion direction (Mz) (as shown in FIG. 1). Figure 1 Figure 1 ​​The third connecting portion 14c and the fourth connecting portion 14d are low in rigidity in the torque direction than the first connecting portion 14a, the second connecting portion 14b, and the third structure 13.

[0054] The thickness of the third connecting portion 14c and the fourth connecting portion 14d in the Fz direction is equal to the thickness of the first structure, the second structure, and the third structure in the Fz direction. The total of the length L11 of the first connecting portion 14a, the length L12 of the second connecting portion 14b, and the length L1 of the third connecting portion 14c and the fourth connecting portion 14d is equal to the length of the third structure 13. Therefore, the rigidity of the third connecting portion 14c and the fourth connecting portion 14d in the Fz direction is slightly lower than the rigidity of the third structure 13 in the Fz direction.

[0055] Further, the total of the length L11 of the first connecting portion 14a, the length L12 of the second connecting portion 14b, and the length L1 of the third connecting portion 14c and the fourth connecting portion 14d is not limited to the case where it is equal to the length of the third structure 13, and can be different.

[0056] Further, in the present embodiment, the structures of the fourth structure 14 and the fifth structure 15 are not limited to this, and can be any structure as long as they can hold the first strain sensor 19 and the second strain sensor 20.

[0057] Figure 6 The portion indicated by B in Figure 1 is enlarged and indicated.

[0058] As described with reference to Figure 2 , the first strain sensor 19 is covered with the shield 16, and the second strain sensor 20 is covered with the shield 17. The shields 16 and 17 are formed of, for example, stainless steel or an iron-based alloy. The shields 16 and 17 prevent mechanical deformation of the first strain sensor 19 and the second strain sensor 20, and protect the plurality of strain gauges 19-2( Figure 8 ). Further, the shields 16 and 17 function as waterproof covers for the first strain sensor 19 and the second strain sensor 20. The detailed waterproof structure is omitted.

[0059] The shields 16 and 17 have the same structure, and therefore, only the shield 16 will be described.

[0060] As Figure 6As shown, the stopper 16 has one end portion 16a and the other end portion 16b, and the width of the other end portion 16b of the stopper 16 is narrower than that of the one end portion 16a. The one end portion 16a of the stopper 16 is, for example, pressed into and fixed to the recessed portion 14f of the fourth structure 14 as an engaging portion formed on the second structure 12 side. The other end portion 16b of the stopper 16 is disposed in the recessed portion 14f of the fourth structure 14 formed on the first structure 11 side. The width of the other end portion 16b of the stopper 16 is narrower than that of the recessed portion 14f disposed on the first structure 11 side, and a gap GP is provided between both sides of the other end portion 16b of the stopper 16 and the side surfaces of the recessed portion 14f, respectively.

[0061] The gap GP is determined in accordance with the rigidity of the third structure 13 and the rated torque. Specifically, in a case where the first structure 11 is deformed by, for example, 10 μm with respect to the second structure 12 when a torque of, for example, 1000 N-m is applied to the torque sensor 10, the gap GP is set to, for example, 10 μm.

[0062] (Structure of fixing device)

[0063] Figure 7 Figure 8 The fixing devices 31 and 32 of the strain sensor of the present embodiment are shown. The fixing device 31 fixes the first end portion of the strain generator 19-1 constituting the first strain sensor 19 to the first connecting portion 14a, and the fixing device 32 fixes the second end portion of the strain generator 19-1 to the second connecting portion 14b.

[0064] The fixing devices 31 and 32 have the same structure, and therefore, the structure of the fixing device 31 is described using the fixing device 31, and the same reference numerals are attached to the same portions in the fixing device 32.

[0065] The fixing device 31 includes a fixing member 41 and a screw 42. The width of the fixing member 41 is slightly narrower than that of the recessed portion 14f, and the side surface of the fixing member 41 can be in contact with the side surface of the recessed portion 14f in a state where the fixing member 41 is disposed in the recessed portion 14f. Therefore, when the fixing member 41 is fastened by the screw as described later, the rotation in the recessed portion 14f is suppressed.

[0066] The fixing member 41 has a protrusion 41a at the first end portion, an angular portion 41b at the second end portion, and a threaded hole 41c between the first end portion and the second end portion.

[0067] The protrusion 41a is in contact with the bottom of the recessed portion 14f. The height Hl of the protrusion 41a is higher than the thickness H2 of the strain generator 19-1. That is, Hl > H2. The angular portion 41b preferably makes line contact with the strain generator 19-1. Therefore, the machining accuracy of the angular portion 41b is preferably 0.1 mm or less in the radius R.

[0068] As shown in FIG. 6, the fixing member 41 is disposed in the recessed portion 14f of the fourth structure 14. The protrusion 41a of the fixing member 41 is in contact with the bottom of the recessed portion 14f.​Figure 8 As shown, the width of the fixing member 41 is wider than the width of the strain generator 19-1, and the corner 41b of the fixing member 41 can make overall contact with the width direction of the first end or the second end of the strain generator 19-1.

[0069] like Figure 7 As shown, the first connecting portion 14a is included in the first structure 11, and the first connecting portion 14a forms the bottom of the recess 14f. A through hole 14a-1 for inserting a screw 42 is provided at the bottom of the recess 14f. The second connecting portion 14b is included in the second structure 12, and the second connecting portion 14b forms the bottom of the recess 14f. A through hole 14b-1 for inserting a screw 42 is provided at the bottom of the recess 14f. When the screw 42 is inserted into the through holes 14a-1 and 14b-1, it is screwed into the threaded hole 41c of the fixing component 41, respectively.

[0070] In the above structure, when the first strain sensor 19 is fixed using fixing device 31 and fixing device 32, such as Figure 7 As shown, the first strain sensor 19 is disposed between the first connecting portion 14a and the second connecting portion 14b. In this state, the corner 41b of the fixing member 41 of the fixing device 31 contacts the first end of the strain generator 19-1 constituting the first strain sensor 19, and the corner 41b of the fixing member 41 of the fixing device 32 contacts the second end of the strain generator 19-1 constituting the first strain sensor 19.

[0071] In this state, when screw 42 is tightened, the fixing member 41 reciprocates (reverses) along the directions of arrows C and D in the diagram, with the protrusion 41a as the fulcrum, and the corner 41b of the fixing member 41 presses against the surface of the strain generator 19-1. Thus, as... Figure 8 As shown, the corner 41b of the fixing member 41 makes line contact with the surface of the strain generator 19-1, and the strain generator 19-1 is fixed to the first connecting part 14a and the second connecting part 14b by two fixing members 41.

[0072] (Effects of the implementation method)

[0073] According to the above embodiment, the fixing member 41 reciprocates with the protrusion 41a as a fulcrum via the fastening screw 42, and the corner 41b makes line contact with the strain generator 19-1. Therefore, compared with the current case where the strain generator and the fixing member make surface contact, the strain generator 19-1 can be fixed with higher pressure relative to the first structure 11 and the second structure 12. Therefore, the unevenness of the fixing strength of the strain generator 19-1 relative to the first structure 11 and the second structure 12 can be reduced.

[0074] Further, according to the fixing method using the fixing member 41 of the present embodiment, the strain generating body 19-1 is fixed to the first structure 11 and the second structure 12 by bringing only the corner portion 41b of the fixing member 41 into line contact with the strain generating body 19-1. Thus, thermal deformation of the strain generating body 19-1 and the strain gauge, which occurs in the case where the strain generating body 19-1 is fixed to the first structure 11 and the second structure 12 by welding, can be prevented. Further, a low-rigidity portion is not interposed between the strain generating body and the first structure 11 and the second structure 12 as in the case where the strain generating body 19-1 is fixed by an adhesive. Thus, according to the fixing method using the fixing member 41 of the present embodiment, a decrease in the sensitivity of the torque sensor 10 can be prevented.

[0075] Further, for example, in the case where the strain generating body is fixed to the structure by using a fixing member and a plurality of screws, the strain generating body is fixed by the fixing member by providing the fixing member, which is wider than the strain generating body, on the strain generating body and screwing a plurality of screws provided on both sides in the width direction of the fixing member to the structure. In this case, the fixing member is deformed by tightening the plurality of screws, and the central portion in the width direction of the fixing member is separated from the surface of the strain generating body. Thus, the effective contact area of the strain generating body and the fixing member decreases, and the fixing strength decreases. Therefore, in order to suppress deformation of the pressing member and obtain a necessary fixing strength, it is necessary to thicken the thickness of the pressing member.

[0076] In contrast, in the present embodiment, the fixing member 41 is returned to the first structure 11 or the second structure 12 side by the one screw 42 provided between the protrusion 41a and the corner portion 41b, and the corner portion 41b of the fixing member 41 is brought into line contact with the strain generating body 19-1. Thus, the corner portion 41b of the fixing member 41 hardly deforms in a direction perpendicular to the width direction of the strain generating body 19-1. Therefore, the corner portion 41b of the fixing member 41 can be brought into line contact with the strain generating body 19-1 without interruption in the width direction. Thus, it is not necessary to thicken the thickness of the fixing member 41 more than necessary in order to obtain a necessary fixing strength, and the fixation member 41 can be prevented from being large-sized.

[0077] Further, the fixing devices 31 and 32 are configured by one fixing member 41 and one screw 42. Thus, the number of parts is small, and the fixation devices 31 and 32 and the torque sensor 10 can be prevented from being large-sized.

[0078] Further, the fixation devices 31 and 32 are configured by one fixing member 41 and one screw 42, and thus, the fixation devices 31 and 32 are easy to assemble.

[0079] Further, the fixing member 41 has a protrusion 41a, but the protrusion 41a is not necessarily provided to the fixing member 41, and can be provided to the first structure 11 and the second structure 12, for example. Specifically, the protrusion 41a can be provided to portions of surfaces of the first connecting portion 14a and the second connecting portion 14b, respectively, which correspond to the first end portion of the fixing member, and the first end portion of the fixing member 41 is placed on the protrusion 41a. That is, the fixing member 41 can be rotatably provided with the protrusion 41a as a fulcrum.

[0080] In addition to the above, the present application is not limited to each of the embodiments described above, and in the implementation stage, the constituent elements can be modified and embodied within a range not departing from the gist thereof. In addition, various applications can be formed by appropriate combinations of the plurality of constituent elements disclosed in each of the embodiments. For example, several constituent elements can be deleted from all the constituent elements indicated in the embodiments. In addition, the constituent elements involved in different embodiments can be appropriately combined.

[0081] Industrial Applicability

[0082] The fixing device of the strain sensor of the present embodiment is applicable to a torque sensor, and the torque sensor is applicable to, for example, a joint of a robot arm.

[0083] Explanation of Symbols

[0084] 10 … torque sensor, 11 … first structure, 12 … second structure, 13 … third structure, 19-1 … strain generator, 31, 32 … fixing device, 41 … fixing member, 41a … protrusion, 41b … corner portion, 42 … screw.

Claims

1. A torque sensor comprising: a first structure body having a first face and a second face parallel to the first face; a second structure body having a third face and a fourth face parallel to the third face; a plurality of third structure bodies connecting the first structure body and the second structure body and having a thickness in a direction perpendicular to the first face and the second face; at least two fourth structure bodies connecting the first structure body and the second structure body and having a recess that is continuous from the first face of the first structure body to the third face of the second structure body, a first connecting portion at a bottom of the recess of the first structure body, and a second connecting portion at a bottom of the recess of the second structure body, a strain generator disposed between the first connecting portion of the first structure body and the second connecting portion of the second structure body and having a thickness thinner than the thickness of the third structure body; a first fixing device disposed at the first connecting portion of the first structure body and fixing a first end portion of the strain generator to the first connecting portion of the first structure body; and a second fixing device disposed at the second connecting portion of the second structure body and fixing a second end portion of the strain generator to the second connecting portion of the second structure body, wherein the first connecting portion of the first structure body includes a first through-hole that penetrates from the first face side to the second face, the second connecting portion of the second structure body includes a second through-hole that penetrates from the third face side to the fourth face, wherein the first fixing device and the second fixing device each have: a fixing member having a third end portion and a fourth end portion, the fourth end portion having a corner portion that makes line contact with the first end portion of the strain generator disposed on the first connecting portion of the first structure body or the second end portion of the strain generator disposed on the second connecting portion of the second structure body; a protrusion as a fulcrum that is disposed only on one of the third end portion of the fixing member and a portion of the first connecting portion of the first structure body corresponding to the third end portion, or only on one of the third end portion of the fixing member and a portion of the second connecting portion of the second structure body corresponding to the third end portion; and a threaded hole disposed at a position other than the protrusion between the third end portion and the fourth end portion of the fixing member, into which a screw inserted into the first through-hole from the second face of the first structure body or a screw inserted into the second through-hole from the fourth face of the second structure body is screwed.

2. The torque sensor according to claim 1, wherein a height of the protrusion is higher than a thickness of the strain generator.

3. The torque sensor according to claim 1 or 2, wherein the fourth end portion of the fixing member has a width wider than a width of the strain generator and makes line contact with the strain generator.

4. The torque sensor according to claim 1, wherein The fourth structure has an opening portion between the first structure and the second structure.

5. The torque sensor according to claim 1, further comprising: a stopper installed in the recess of the fourth structure.

6. The torque sensor according to claim 5, wherein the stopper includes a fifth end portion on the first structure side and a sixth end portion on the second structure side, and the width of the fifth end portion is narrower than the width of the recess.

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