JP2006071506A - Multiaxial force sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable multi-axial force sensor with a simple structure. <P>SOLUTION: The multiaxial force sensor detects at least the forces of three components activating in the X-axis, Y-axis, and Z-axis coordinate directions perpendicular to each other and also detects the moment round the X-axis and Y-axis. The sensor is composed of: an outer ring part 2 having the ring internal periphery surface 20 centering on the coordinate origin O, on the reference plane including the X-axis and Y-axis; an internal ring part 3 having the ring outer periphery surface 30 facing to the inner periphery surface 20 of the outer part 2; and a plurality of load sensor elements 4 connecting the internal periphery surface 20 and the outer periphery surface 30. The inner periphery surface 20 of the outer ring part 2 is provided with a tapered internal surface to the Z-axis, the outer periphery surface 30 of the internal ring part 3 facing the tapered internal surface is provided with the tapered outer surface to the Z-axis, and the load sensor elements 4 are interposed between the tapered internal surface and the tapered outer surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-axis force sensor capable of detecting at least one of three force components in the X-axis, Y-axis, and Z-axis coordinate axis directions acting on the origin of the sensor, and a moment component around each axis.

Although automobiles, industrial robots, and other mechanical devices continue to advance to more multifunctional devices, high-precision sensors are indispensable as components. In particular, if the magnitude and direction of force can be accurately detected by one sensor, very precise control can be realized.
For this reason, multi-axis force sensors have been developed so far, for example, as disclosed in Patent Documents 1 to 3.

  However, conventional multi-axis force sensors are mainly composed of a combination of a strain generating body that actually receives a load or the like and a strain gauge that detects a shearing force or the like applied to the strain generating body. It is complicated, expensive to manufacture, and the measurement accuracy is not sufficient, and further improvement has been desired.

JP-A-7-12664 JP-A-7-72026 JP-A-2-268240

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a multi-axis force sensor having a simple structure and high reliability.

The present invention is a multi-axis force sensor capable of detecting at least three components in the coordinate axis direction acting in the X-axis, Y-axis, and Z-axis directions orthogonal to each other, and the moments about the X-axis and the Y-axis. ,
An outer ring portion having a ring-shaped inner peripheral surface centering on the coordinate origin on a reference plane including the X axis and the Y axis;
An inner ring portion having a ring-shaped outer peripheral surface facing the inner peripheral surface of the outer ring portion;
It consists of a plurality of load sensor elements that connect the inner peripheral surface and the outer peripheral surface,
The inner peripheral surface of the outer ring portion has a tapered inner surface inclined with respect to the Z axis, and the outer peripheral surface of the inner ring portion is inclined with respect to the Z axis so as to face the tapered inner surface. And the load sensor element is sandwiched between the tapered inner surface and the tapered outer surface. (Claim 1)

  As described above, the multi-axis force sensor of the present invention includes the outer ring portion, the inner ring portion, and the plurality of load sensor elements sandwiched between them, and has a very simple structure. Furthermore, the inner peripheral surface and the outer peripheral surface have a tapered outer surface and a tapered inner surface that are inclined with respect to the Z-axis, and a plurality of the load sensor elements are sandwiched therebetween. Therefore, by fixing the outer ring part or the inner ring part and inputting the force to be measured to the inner ring part or the outer ring part, not only the X axis direction and the Y axis direction but also the Z axis direction force can be detected. . Further, by detecting these axial forces, it is possible to detect at least a moment around the X axis and a moment around the Y axis.

What should be noted here is that the multi-axis force sensor has the load sensor elements arranged as described above, thereby connecting the outer ring portion and the inner ring portion. By adopting such a structure, the force input to the outer ring portion or the inner ring portion is not transmitted via other members such as a strain body, but directly transmitted to the load sensor element. . Therefore, the input force can be sensed with extremely high accuracy, and the detection accuracy can be improved.
As described above, the multi-axis force sensor of the present invention is not only simple in structure but also stable in structure and performance and has high reliability.

  In the multi-axis force sensor of the present invention, the load sensor element has a pressure receiving surface on two parallel outer surfaces, and a pressure sensitive body that changes electrical characteristics when receiving a uniaxial load from the pressure receiving surface. Preferably, one of the pressure receiving surfaces is in contact with or joined to the tapered inner surface, and the other pressure receiving surface is in contact with or joined to the tapered outer surface. By adopting a load sensor element having a pressure-sensitive body that can directly detect and detect such a uniaxial load, a structure that is sandwiched between the outer ring portion and the inner ring portion can be easily realized.

As the pressure-sensitive body, for example, it is possible to employ composite ceramics in which a material having a pressure resistance effect or a magnetoresistance effect is dispersed in a base material made of ceramics having electrical insulation properties so as to be electrically connected. Is possible. In addition, it is needless to say that a pressure-sensitive body having a configuration other than the above can be adopted as long as the material can change the electrical characteristics according to the received stress.
Moreover, it is preferable to provide insulating parts made of ceramics having electrical insulation properties on both surfaces of the pressure-sensitive body, which are used as pressure-receiving surfaces. Thereby, electrical insulation between the outer ring portion and the inner ring portion and the load sensor element can be easily ensured.

  The load sensor element is preferably configured to detect only compressive stress (claim 3). That is, by using a load sensor element that detects only the compressive stress and does not detect the shear stress, the multiaxial force can be accurately obtained even when the shear stress is input.

  Also, the X plane is a plane that is orthogonal to the X axis and includes the coordinate origin, and a Y plane that is a plane that is orthogonal to the Y axis and includes the coordinate origin. (Claim 4). In this case, when calculating the forces and moments in the axial direction by calculating the outputs from the plurality of load sensor elements, the calculation is performed using the fact that they are structurally symmetrical at least in the X-axis direction and the Y-axis direction. Time correction processing can be simplified. Furthermore, since it is structurally stable, the stability and reliability of the entire multi-axis force sensor can be further improved.

  The plurality of load sensor elements are preferably arranged at symmetrical positions with respect to a Z plane which is a plane orthogonal to the Z axis and including the coordinate origin (claim 5). In this case, since the structure is symmetrical also in the Z-axis direction, the correction process at the time of calculating the output from each load sensor element can be further simplified, and further, the structure of the multi-axis force sensor is further improved. Stability and reliability can be improved.

  The tapered inner surface is formed in a concave shape or a convex shape by connecting a first tapered inner surface inclined in a predetermined direction and a second tapered inner surface inclined in the opposite direction. The first taper outer surface inclined in a predetermined direction so as to face the one taper inner surface and the second taper outer surface inclined in the opposite direction and facing the second taper inner surface are formed into a convex shape or a concave shape. The load sensor element is preferably sandwiched between the first tapered inner surface and the first tapered outer surface, and between the second tapered inner surface and the second tapered outer surface. 6).

In this case, the force in one direction along the Z axis is measured by a first group of load sensor elements sandwiched between the first tapered inner surface and the first tapered outer surface, and the force in the other direction is A plurality of load sensor elements can be easily assigned to roles as measured by a second group of load sensor elements sandwiched between the second tapered inner surface and the second tapered outer surface. Furthermore, it is possible to limit the direction of measurement to only the compressive force. Therefore, measurement accuracy is further increased and reliability is further improved.
In addition, the combination of the concave or convex shape in the outer ring portion and the convex or concave shape in the inner ring portion can further stabilize the combination shape of both.

  Further, the outer ring part or the inner ring part is divided into two parts in the thickness direction, and the load sensor element is sandwiched between the outer ring part and the inner ring part by adjusting the distance between them. It is preferable that the preload with respect to can be adjusted (Claim 7). In this case, an optimum preload for the adopted load sensor element can be set by adjusting the interval between the two components. By setting the preload, all load sensor elements can respond to tension or compression input. That is, the multi-axis force can be detected with high accuracy. Therefore, the measurement accuracy, stability, and structural stability of the multi-axis force sensor can be further enhanced.

  Further, the inner peripheral surface of the outer ring portion is formed in a convex shape with the central portion having the smallest diameter connecting the first tapered inner surface and the second tapered inner surface, and the tapered outer surface of the inner ring portion is The first taper inner surface and the second taper inner surface are connected to each other so that the central portion is formed in a concave shape having the smallest diameter, and the inner ring portion is divided into two parts in the thickness direction, It is preferable that the preload is increased by reducing the distance between the two, and the preload can be decreased by increasing the distance between the two. In this case, since the inner ring part can be constituted by two parts and the outer ring part can be constituted by one part, the outer ring part can be easily fixed and a structure that can be easily installed can be realized. Also, since the shape of the inner ring part is concave with the central part having the smallest diameter, when it is combined with the outer ring part in a state of being divided into two parts, it is inserted so as to be sandwiched from both sides on the inner peripheral side Can be assembled easily.

  In addition, the two parts of the inner ring part are configured to reduce the interval by tightening the bolts, and a shim for adjusting the tightening force is disposed between the two parts. Preferred (claim 9). In this case, the two parts constituting the inner ring portion can be easily combined, and the interval can be easily adjusted by selecting the thickness of the shim, and the tightening force can be increased by the presence of the shim. It can be adjusted easily.

Example 1
A multi-axis force sensor according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the multi-axis force sensor 1 of this example includes at least a force 3 in the coordinate axis direction acting in the X axis (X), Y axis (Y) and Z axis (Z) directions orthogonal to each other. A multi-axis force sensor capable of detecting a component and moments Mx and My about the X axis and the Y axis.
The multi-axis force sensor 1 faces the outer ring portion 2 having a ring-shaped inner peripheral surface centered on the coordinate origin O on a reference plane including the X axis and the Y axis, and the inner peripheral surface 20 of the outer ring portion 2. The inner ring portion 3 having a ring-shaped outer peripheral surface 30 and a plurality of load sensor elements 4 that connect the inner peripheral surface 20 and the outer peripheral surface 30.

The inner peripheral surface 20 of the outer ring portion 2 has tapered inner surfaces 21 and 22 inclined with respect to the Z axis, and the outer peripheral surface 30 of the inner ring portion 3 is inclined with respect to the Z axis so as to face the tapered inner surfaces 21 and 22. Taper outer surfaces 31, 32. The load sensor element 4 is sandwiched between the tapered inner surfaces 21 and 22 and the tapered outer surfaces 31 and 32.
Further details will be described below.

As shown in FIG. 3, the load sensor element 4 of the present example has pressure receiving surfaces 41 and 42 on two parallel outer surfaces, and changes electrical characteristics when receiving a uniaxial load from the pressure receiving surfaces 41 and 42. A pressure-sensitive body 400 is provided. Insulating portions 401 and 402 made of ceramic having electrical insulation are disposed on both surfaces of the pressure sensitive body 400, and the surfaces thereof are the pressure receiving surfaces 41 and 42, respectively. In addition, electrodes 45 for taking out a change in electric resistance of the pressure sensitive body 400 are provided on both end surfaces in a direction orthogonal to the stacking direction of the insulating portion 401, the pressure sensitive body 400, and the insulating portion 402. Connected to the output line.
As shown in FIG. 2, the load sensor element 4 has one pressure receiving surface 41 in contact with or joined to the tapered inner surfaces 21, 22 and the other pressure receiving surface 42 in contact with or joined to the tapered outer surfaces 31, 32. I am letting.

Further, as shown in FIG. 4, the pressure-sensitive body 400 constituting the load sensor element 4 is configured so that a sensor material 408 having a pressure resistance effect is electrically connected to a base material 409 made of ceramic having electrical insulation properties. It consists of composite ceramics that are dispersed. Various materials can be used as the ceramic material for the base material 409. In this example, zirconia is used. Various materials can be used as the sensor material 408 having the pressure resistance effect, but (La, Sr) MnO ₃ is used in this example. The load sensor element 4 using the pressure-sensitive body 400 is configured to detect only compressive stress.
Of course, any material other than those described above can be used as the pressure-sensitive body 400 as long as the electrical characteristics can be changed according to the pressure received.

As shown in FIG. 2, the tapered inner surfaces 21 and 22 of the outer ring portion 2 are convexly formed by connecting the first tapered inner surface 21 inclined in a predetermined direction and the second tapered inner surface 22 inclined in the opposite direction. Is formed.
Further, the tapered outer surfaces 31 and 32 in the inner ring portion 3 face the second tapered inner surface 22 inclined in the opposite direction to the first tapered outer surface 31 inclined in a predetermined direction so as to face the first tapered inner surface 21. The second tapered outer surface 32 is connected to form a concave shape.
The load sensor element 4 was sandwiched between the first taper inner surface 21 and the first taper outer surface 31 and between the second taper inner surface 22 and the second taper outer surface 32.

  In addition, as shown in FIG. 2, the inner ring portion 3 is divided into two parts 301 and 302 in the thickness direction, and is clamped between the outer ring portion 2 and the inner ring portion 3 by adjusting the distance between them. The preload for the load sensor element 4 is configured to be adjustable. More specifically, the preload is increased by reducing the distance between the two parts 301 and 302, and the preload can be reduced by increasing the distance between the two parts.

  Furthermore, as shown in the figure, the two parts 301 and 302 of the inner ring portion 3 are configured to reduce the interval by tightening the bolt 6, and the tightening force is adjusted between the two parts 301 and 302. A shim 65 is provided for this purpose. By adopting such a structure, the tightening force can be adjusted to a predetermined value, and the tightening force can be prevented from becoming too strong. Further, the interval can be easily adjusted by changing the thickness of the shim 65, whereby the preload can be easily adjusted. In this example, a through hole 391 and a screw hole 392 are provided in the inner ring portion 3 and a through hole 659 is also provided in the shim 65 so as to obtain such a bolt fastening structure.

As shown in FIGS. 1 and 2, the load sensor element 4 includes an X plane that is a plane orthogonal to the X axis and including the coordinate origin O, and a Y plane that is orthogonal to the Y axis and includes the coordinate origin O. It is arranged at a position symmetrical to the plane and all the Z planes that are orthogonal to the Z axis and include the coordinate origin O. More specifically, as shown in FIG. 1, on the reference plane, the load sensor elements 4 are arranged at equal intervals on four locations on the X axis and the Y axis. Further, when viewed in the Z-axis direction, it is divided into upper and lower portions symmetrically across the reference plane, that is, the first group between the first taper inner surface 21 and the first taper outer surface 31, and the second taper inner surface 22. The second group is arranged symmetrically with the second taper outer surface 32.
In this example, the inclination angle α1 of the first taper inner surface 21 and the first taper outer surface 31 with respect to the Z axis and the inclination angle α2 of the second taper inner surface 22 and the second taper outer surface 32 with respect to the Z axis are the same 22.5. Set to °.

As described above, the multi-axis force sensor 1 of the present example is configured by the outer ring portion 2, the inner ring portion 3, and the plurality of load sensor elements 4 sandwiched therebetween, and the structure is very simple. .
Furthermore, the multi-axis force sensor 1 arranges the load sensor element 4 as described above, and thereby connects the outer ring portion 2 and the inner ring portion 3. By adopting such a structure, the outer ring portion 2 is fixed, and the force to be measured is input to the inner ring portion 3, so that the load sensor element 4 is directly connected to the load sensor element 4 without any other member such as a strain body. The force can be transmitted. Therefore, the input force can be sensed with extremely high accuracy, and detection accuracy can be improved.

Further, in this example, the inner ring portion 3 is divided in the thickness direction, and the tapered shape of the outer peripheral surface 30 is a concave shape having the smallest diameter at the central portion. Therefore, when it is combined with the outer ring portion 3 in a state of being divided into two, it can be easily assembled by inserting the inner ring side so as to be sandwiched from both sides. Then, by tightening the bolt 6 with the shim 65 interposed therebetween, a stable structure can be realized, and an optimal preload can be applied to each load sensor element 4 by selecting the thickness of the shim 65.
Further, as described above, since the arrangement of the load sensor elements 4 is symmetric with respect to the X, Y, and Z planes, the axial load and moment in each direction can be detected from the output values of the load sensor elements 4. And the like can be simplified.

(Example 2)
As shown in FIGS. 5 and 6, the multi-axis force sensor 102 of the present example has the same basic structure as the multi-axis force sensor 1 in the first embodiment, but the outer ring portion 2 and the inner ring portion 3 are finer. The shape is changed.
As shown in FIGS. 5 and 6, the multi-axis force sensor 102 of the present example is greatly different from that of the first embodiment, as shown in FIGS. 5 and 6, the inclination angle β1 of the first tapered inner surface 21 and the first tapered outer surface 31 with respect to the Z axis, The inclination angle β2 of the two taper inner surface 22 and the second taper outer surface 32 with respect to the Z axis is set to the same 45 °, which is larger than that in the first embodiment. Thus, by increasing the inclination angles β1 and β3, the force in the Z-axis direction can be measured with higher sensitivity.
In other respects, the same effects as those of the first embodiment can be obtained.

(Example 3)
As shown in FIG. 7, this example is an example in which the arrangement of the load sensor element 4 on the reference plane is changed to eight places based on the structure of the second embodiment.
In this case, the increase in the load sensor element 4 enables detection with higher precision and at the same time makes the structure more stable.
In other respects, the same effects as those of the first embodiment can be obtained.

FIG. 3 is a plan view of a multi-axis force sensor in the first embodiment. 1 is a longitudinal sectional view of a multi-axis force sensor in Embodiment 1. FIG. FIG. 3 is an explanatory diagram illustrating a configuration of a load sensor employed in the multi-axis force sensor in the first embodiment. FIG. 3 is an explanatory diagram illustrating a configuration of a pressure sensitive body in the load sensor in the first embodiment. The top view of the multi-axis force sensor in Example 2. FIG. FIG. 6 is a longitudinal sectional view of a multi-axis force sensor in Embodiment 2. FIG. 6 is a plan view of a multi-axis force sensor in Embodiment 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multi-axis force sensor 2 Outer ring part 20 Inner peripheral surface 21 1st taper inner surface 22 2nd taper inner surface 3 Inner ring part 30 Outer surface 31 1st taper outer surface 32 2nd taper outer surface 4 Load sensor element 6 Bolt 65 Shim

Claims (9)

A multi-axis force sensor capable of detecting at least three force components in the coordinate axis direction acting in the X-axis, Y-axis, and Z-axis directions orthogonal to each other, and a moment about the X-axis and the Y-axis,
An outer ring portion having a ring-shaped inner peripheral surface centering on the coordinate origin on a reference plane including the X axis and the Y axis;
An inner ring portion having a ring-shaped outer peripheral surface facing the inner peripheral surface of the outer ring portion;
It consists of a plurality of load sensor elements that connect the inner peripheral surface and the outer peripheral surface,
The inner peripheral surface of the outer ring portion has a tapered inner surface inclined with respect to the Z axis, and the outer peripheral surface of the inner ring portion is inclined with respect to the Z axis so as to face the tapered inner surface. A multi-axis force sensor, wherein the load sensor element is sandwiched between the tapered inner surface and the tapered outer surface.   In claim 1, the load sensor element has a pressure receiving surface on two parallel outer surfaces, and a pressure sensitive body that changes electrical characteristics when receiving a uniaxial load from the pressure receiving surface. One of the pressure receiving surfaces is brought into contact with or joined to the tapered inner surface, and the other pressure receiving surface is brought into contact with or joined to the tapered outer surface.   3. The multi-axis force sensor according to claim 1, wherein the load sensor element is configured to detect only a compressive stress.   The load sensor element according to any one of claims 1 to 3, wherein the load sensor element is an X plane that is orthogonal to the X axis and includes the coordinate origin, and a plane that is orthogonal to the Y axis and includes the coordinate origin. A multi-axis force sensor, wherein the multi-axis force sensor is disposed at a symmetrical position with respect to both of the Y planes.   5. The multi-axis force sensor according to claim 4, wherein the plurality of load sensor elements are arranged at symmetrical positions with respect to a Z plane which is a plane orthogonal to the Z axis and including the coordinate origin. . 6. The taper inner surface according to claim 1, wherein the tapered inner surface is formed in a concave shape or a convex shape by connecting the first tapered inner surface inclined in a predetermined direction and the second tapered inner surface inclined in the opposite direction. And
The taper outer surface is formed by connecting a first taper outer surface inclined in a predetermined direction so as to face the first taper inner surface and a second taper outer surface inclined in the opposite direction and facing the second taper inner surface. Formed in a shape or a concave shape,
The load sensor element is sandwiched between the first taper inner surface and the first taper outer surface, and between the second taper inner surface and the second taper outer surface, respectively. Sensor.   In Claim 6, the said outer ring part or the said inner ring part is divided | segmented into two parts in the thickness direction, The said clamped between the said outer ring part and the said inner ring part by adjusting the space | interval of both A multi-axis force sensor configured to be capable of adjusting a preload applied to a load sensor element. In Claim 7, the said inner peripheral surface of the said outer ring | wheel part is formed in the convex shape in which the center part becomes the smallest diameter connecting the said 1st taper inner surface and the said 2nd taper inner surface, The tapered outer surface is formed in a concave shape in which the central portion has the smallest diameter by connecting the first tapered inner surface and the second tapered inner surface.
In addition, the inner ring part is divided into two parts in the thickness direction, and it is possible to increase the preload by reducing the distance between the two, and to reduce the preload by increasing the distance between the two. A multi-axis force sensor characterized by being configured as described above.   In claim 8, the two parts of the inner ring part are configured to reduce the interval by tightening a bolt, and a shim for adjusting the tightening force is disposed between the two parts. A multi-axis force sensor.

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