JP5117804B2 - 6-axis force sensor - Google Patents

Description

  The present invention relates to a six-axis force sensor that can detect three force components in the coordinate axis directions of the X, Y, and Z axes acting on the origin of the sensor and three moment components 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 a single sensor can accurately detect the magnitude and direction of the force, very precise control can be realized.
Therefore, development of a multi-axis force sensor has been made so far, for example, as disclosed in Patent Documents 1 to 10.

Conventional multi-axis force sensors are mainly composed of a structure in which a strain body that actually receives a load or the like and a strain gauge that detects a shear force or the like applied thereto is combined. However, a sensor combining a plurality of strain gauges has a complicated structure and is difficult to miniaturize, is not suitable for mass production, and has a problem in reliability.
In addition, although a configuration that avoids the use of a strain gauge has been proposed, a so-called 6-axis force sensor has a very complicated configuration and is often difficult to downsize.

JP-A-7-12664 JP-A-7-72026 JP-A-2-268240 JP 2007-108079 A JP 2006-275650 A JP 2003-254843 A JP 2003-207405 A Japanese Patent Laid-Open No. 2002-221459 JP 9-318469 A JP-A-8-122178

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

The present invention is a six-axis force sensor capable of detecting forces in the coordinate axis direction acting in the X-axis, Y-axis, and Z-axis directions orthogonal to each other, and moments about the X-axis, Y-axis, and Z-axis. ,
An annular outer member centered on a coordinate origin on a reference plane including the X axis and the Y axis;
An inner member having an outer peripheral surface disposed with a gap inside the inner peripheral surface of the outer member;
A plurality of load sensor elements sandwiched between an outer element installation surface provided on the inner peripheral surface of the outer member and an inner element installation surface provided on the outer peripheral surface of the inner member;
The inner element installation surface of the inner member is provided so as to form a recess opposite to both sides across a reference plane including the X axis and the Y axis, and of the inner element installation surface, The plurality of first inner element installation surfaces present on one side across the reference plane correspond to at least a part of the side surface of the first polygonal pyramid having an apex on the Z axis in the reference plane, and the reference plane The plurality of second inner element installation surfaces existing on the other side across the top have a vertex on the Z axis in the reference plane and have the same shape as the second polygonal pyramid facing in the opposite direction to the first polygonal pyramid It is provided to correspond to at least a part of the side surface of
The outer element installation surface of the outer member is provided on both sides of the reference plane including the X-axis and the Y-axis so as to form convex portions accommodated in the recesses in opposite directions, and A plurality of first outer element installation surfaces present on one side of the reference plane between the outer element installation surfaces are arranged substantially parallel to the first inner element installation surface, and the reference plane is defined as A plurality of second outer element installation surfaces present on the other side of the sandwich are arranged substantially parallel to the second inner element installation surface,
Two or more load sensor elements are arranged in one sensor installation region existing between the pair of opposed inner element installation surfaces and the outer element installation surface, respectively. It exists in a 6-axis force sensor (Claim 1).

  As described above, the six-axis force sensor according to the present invention includes the outer member, the inner member, and the plurality of load sensor elements sandwiched between them, and has a very simple structure. Further, it should be noted that the first polygonal pyramid and the second polygonal pyramid in which the inner element installation surface provided on the inner member has an apex on the Z axis in a reference plane including the X axis and the Y axis. It consists of a plane corresponding to at least a part of the side surface of the polygonal pyramid, and the outer element installation surface is also substantially parallel to the inner element installation surface, and similarly consists of a plane corresponding to at least a part of the side surface of the polygonal pyramid. It is.

When the polygonal pyramid is an n-pyramid (n is a natural number of 3 or more), the first inner element installation surface and the second inner element installation surface, and the first outer element installation surface and the second outer element installation surface are , Both are constituted by n planes. And in one said 6-axis force sensor, the said sensor installation area | region which exists between one set of the said inner element installation surface and the said outer element installation surface which exists in two Z-axis direction exists, There will be n locations in the circumferential direction, for a total of 2n locations.
Further, as described above, since two or more load sensor elements are arranged in one sensor installation region, a total of 4n or more load sensor elements are arranged.

  In addition, since each of the element installation surfaces corresponds to a part of the side surface of the polygonal pyramid, the element installation surface is always inclined by a predetermined angle with respect to the Z-axis direction, and at least one of the X-axis direction or the Y-axis direction Are always inclined at a predetermined angle. Therefore, by calculating the relationship between the placement position and output of each load sensor element from the geometric point of view, the forces in the coordinate axis direction acting in the X axis, Y axis and Z axis directions orthogonal to each other, and the above X axis The moment about the Y axis and the Z axis, that is, the six-axis force can be detected.

The 6-axis force sensor does not require the use of a strain-generating body as in the prior art, and can directly use the output of the load sensor element, so that the structure is very simple and accurate measurement is possible. The number of parts is small, and the reliability and durability are excellent.
Therefore, according to the present invention, it is possible to provide a 6-axis force sensor having a simple structure and high reliability.

In the six-axis force sensor of the present invention, as described above, the inner element installation surface provided on the inner member is a plane corresponding to at least a part of the side surfaces of the first polygonal pyramid and the second polygonal pyramid, and The outer element installation surface is also substantially parallel to the inner element installation surface, and is similarly formed of a plane corresponding to at least a part of the side surfaces of a polygonal pyramid (referred to as a third polygonal pyramid and a fourth polygonal pyramid).
The first polygonal pyramid and the second polygonal pyramid are formed in the same shape with the apex direction turned 180 ° in the opposite direction. And you can select whether the vertices face each other so that they don't overlap each other, only the vertices overlap, or they overlap each other and one vertex goes inside the other polygonal pyramid It is. The third polygonal pyramid is arranged in the same posture as the first polygonal pyramid and is shifted by the distance between the first inner element installation surface and the first outer element installation surface. The pyramids are arranged in the same posture as the second polygonal pyramid and shifted by the distance between the second inner element installation surface and the second outer element installation surface.

Further, the load sensor element is formed of a laminated body integrally laminated with a pressure sensitive body interposed between a pair of electrically insulating pressure receiving bodies, and the pressure sensitive body has a piezoresistive effect. (Claim 2).
Any load sensor element can be used as long as it can output the load received by itself as an electrical characteristic. Among many load sensor elements, a configuration in which the pressure sensitive body having the piezoresistance effect is sandwiched between the pair of electrically insulating pressure receiving bodies is particularly effective.

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 the said pressure receiving body which consists of insulating materials consisting of the ceramics which have electrical insulation, etc. on both surfaces of the said pressure sensitive body. Thereby, the electrical insulation between an outer member and an inner member, and a load sensor element is easily securable.
Moreover, as said pressure receiving body, ceramics, such as a zirconia, etc. are employable, for example.
Moreover, it is preferable that the said load sensor element is comprised so that only a compressive stress may be detected. That is, by using a load sensor element that detects only the compressive stress and does not detect the shear stress, the six-axis force can be accurately obtained even when the shear stress is input.

  The polygonal pyramid is a quadrangular pyramid, and the inner member and the outer member preferably have the inner element installation surface and the outer element installation surface at four circumferential positions around the Z axis, respectively. (Claim 3). In the case of a quadrangular pyramid, eight sensor installation regions can be formed, and at least a total of 16 load sensor elements can be used. Therefore, practically sufficient types of outputs can be obtained and detection can be performed with high accuracy. Furthermore, it is advantageous in terms of cost.

As will be described later, the polygonal pyramid can be a triangular pyramid, and a practically sufficient detection accuracy can be obtained, but the case of a square pyramid is more advantageous in terms of the number and shape stability of the load sensor elements. is there.
Of course, a pentagonal pyramid or larger polygonal pyramid may be used. Of course, it is considered that the accuracy increases as the number of sensor installation areas increases. However, it is necessary to consider disadvantages due to an increase in the manufacturing cost and the number of parts. Practically, a range of 3 to 8 pyramids is preferable, and most preferable is the above-mentioned quadrangular pyramid.

Here, the polygonal pyramid is “when a line segment (bus line) connecting each point on the circumference of the polygon (bottom surface) on the plane and one point (vertex) not on the plane is drawn. In the present invention, the “one point” corresponds to the “vertex” existing on the Z axis, and the bottom surface is an arbitrary position parallel to the reference plane. It becomes the plane of.
Further, the polygonal pyramid in the present invention is most preferably a “regular polygonal pyramid”, and the bottom surface is preferably a regular polygon, so that structural stability can be improved and calculation can be facilitated. .

  Moreover, it is preferable that the angle which the said inner element installation surface and the said outer element installation surface make with the said Z-axis exists in the range of 10 degrees-80 degrees. If the angle is less than 10 °, there is a possibility that a force in the Z-axis direction, that is, Fz described later cannot be detected accurately. On the other hand, if the angle exceeds 80 °, a force in the X-axis direction (described later) Fx) or force in the Y-axis direction (Fy described later) may not be detected with high accuracy.

Further, an inner fixing portion is provided at one axial end portion of the inner member, and the inner fixing portion has an outer diameter larger than the inner diameter of the outer member without contacting the outer member. It is preferably formed in a bowl shape (Claim 5).
In this case, stability when the inner member is fixed to the external input member can be enhanced.

Further, the inner member is constructed by forming the first inner part having the first inner element installation surface and the second inner part having the second inner element installation surface as separate members, and combining them. (Claim 6).
In this case, the inner member can be easily manufactured, and the outer member and the load sensor element can be easily assembled.

  Further, by adjusting the thickness of the inner member, or by adjusting the thickness of the spacer member constituted by the first inner portion and the second inner portion and disposed between the inner member and the load, It is preferable that the preload applied to the sensor element is adjustable. In this case, the preload condition can be easily adjusted, and the measurement accuracy can be further increased.

Example 1
A six-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 six-axis force sensor 1 of this example includes forces in the X-axis, Y-axis, and Z-axis directions that are orthogonal to each other, and the X-axis, Y-axis, and Z-axis. This is a 6-axis force sensor capable of detecting a moment around the axis.

  As shown in FIGS. 1 and 2, the six-axis force sensor 1 includes an annular outer member 2 centering on a coordinate origin O on a reference plane P including the X axis and the Y axis, and an inner circumference of the outer member 2. An inner member 3 having an outer peripheral surface arranged with a gap inside the surface, an outer element installation surface 24 provided on the inner peripheral surface of the outer member 2, and the outer peripheral surface of the inner member 3. And a plurality of load sensor elements 5 sandwiched between the inner element installation surface 34.

  The inner element installation surface 34 of the inner member 3 is provided so as to form a recess 39 facing both sides across the reference plane P including the X axis and the Y axis, and the inner element installation surface 34. Among the plurality of first inner element installation surfaces 34 (a) existing on one side of the reference plane P, the first polygonal pyramid 71 (having a vertex 710 on the Z axis in the reference plane P) The plurality of second inner element installation surfaces 34 (b) corresponding to at least a part of the side surface of FIGS. 2 and 7 and existing on the other side across the reference plane P are the Z in the reference plane P. It is provided so as to correspond to at least a part of the side surface of the second polygonal pyramid 72 (FIG. 2) having the apex 720 on the axis and facing in the opposite direction to the first polygonal pyramid 71.

The outer element installation surface 24 of the outer member 2 forms convex portions 29 accommodated in the recesses 39 in opposite directions on both sides of the reference plane P including the X axis and the Y axis. The plurality of first outer element installation surfaces 24 (a) provided on one side of the outer element installation surface 24 across the reference plane P are respectively the first inner element installation surfaces 34. A plurality of second outer element installation surfaces 24 (b) arranged substantially parallel to (a) and located on the other side across the reference plane P are respectively the second inner element installation surface 34 (b) and the second inner element installation surface 34 (b). They are arranged substantially in parallel.
Two load sensor elements 5 are disposed in one sensor installation region existing between the pair of the inner element installation surface 34 and the outer element installation surface 24 facing each other.
This will be described in more detail below.

  As shown in FIG. 2, the inner member 3 is configured by combining two first inner portions 31 and second inner portions 32 having a rectangular outer peripheral shape with corners chamfered in a curved shape. As shown in FIGS. 3 to 6, the first inner portion 31 has four first inner element installation surfaces 34 (a) formed by tapered planes inclined by a predetermined angle α from the Z axis (FIG. 5). Do it. As shown in FIG. 7, the first inner element installation surface 34 (a) is provided so as to correspond to a part of the side surfaces 711 to 714 of the first polygonal pyramid (square pyramid) 71. Similarly, the second inner portion 32 includes four second inner element installation surfaces 34 (b) each having a tapered plane inclined by a predetermined angle α from the Z axis (FIG. 2). The second inner element installation surface 34 (b) is provided so as to correspond to a part of the side surface of the second polygonal pyramid 72 (FIG. 2) having the same shape as the first polygonal pyramid (square pyramid) 71. .

Further, as shown in FIG. 4, adjacent first inner element installation surfaces 34 (a) in the first inner portion 31 are connected by a curved surface portion 435 that is a curved surface that smoothly changes the direction of 90 °. Each first inner element installation surface 34 (a) has two element installation scheduled areas S at both ends thereof.
The first inner portion 31 is provided with four bolt holes 315 for inserting inner fastening bolts to be integrated with the second inner portion 32, and the outer diameter of the central portion is substantially the same as that of the outer member 2. A central hole 316 is provided for connection to the same bowl-shaped inner fixing portion 6. The configuration in which the curved surface portion 435, the bolt hole 315, and the central hole 316 are provided is the same in the second inner portion 32 (not shown).
Then, as shown in FIG. 2, the inner element installation surface 34 provided on the outer peripheral surface of the inner member 3 is connected to the second inner portion 32 via a spacer member 81 described later, so that the X The recess 39 is formed so as to be opposed to both sides across the axis and the reference plane P including the Y axis.

  Further, as shown in FIGS. 11 and 12, the inner fixing portion 6 connected to the inner member 3 includes a disc-shaped flange portion 61 and a pipe-shaped shaft portion 62 inserted into the central hole 316 of the inner member 3. have. In addition, the flange portion 61 has four inner fixing holes 611 for fixing it, and two knock pin insertion holes 612.

As shown in FIGS. 1, 2, 8, and 9, the outer member 2 has an annular shape in which the outer peripheral shape is circular and the inner peripheral shape is a quadrangular shape with corners chamfered into curved surfaces. And the inner peripheral surface forms the convex part 29 accommodated in the recess 39 of the said inner member 3 at intervals.
The convex portion 29 has four outer element installation surfaces 24 (a) and 24 (b) each formed of a tapered plane inclined on the both sides by a predetermined angle α from the Z-axis (FIG. 9). Become.

Among the outer element installation surfaces 24 of the outer member 2, a plurality of first outer element installation surfaces 24 (a) existing on one side across the reference plane P are respectively the first inner side as shown in FIG. It is arranged substantially parallel to the element installation surface 34 (a). That is, the first outer element installation surface 24 (a) is also provided so as to correspond to a part of the side surface of the quadrangular pyramid 74 (FIG. 9) having the same shape as the first polygonal pyramid (quadratic pyramid) 71.
Further, among the outer element installation surfaces 24, a plurality of second outer element installation surfaces 24 (b) existing on the other side across the reference plane are substantially the same as the second inner element installation surfaces 34 (b), respectively. They are arranged in parallel. That is, the second outer element installation surface 24 (b) is also provided so as to correspond to a part of the side surface of the quadrangular pyramid 74 (FIG. 9) having the same shape as the second polygonal pyramid (quadratic pyramid) 72.

Further, each outer element installation surface 24 is provided in a state of being slightly depressed from the periphery 249 thereof, and the outer peripheral side corners 248 at both ends thereof are formed in an arc shape. The arc-shaped corner portion 248 is made to correspond to the shape of one pressure receiving body 51 constituting the load sensor element 5 described later, so that the position where the load sensor element 5 is disposed can be easily positioned.
Further, four outer fixing holes 23 are provided on the front side on the outer peripheral side of each outer element installation surface 24 of the outer member 2, and two knock pin insertion holes 26 for inserting a knock pin 85 described later are provided on the back side. It has been.

As shown in FIGS. 13 and 14, the load sensor element 5 is composed of a laminated body in which a pressure-sensitive body 50 is interposed between a pair of electrically insulating pressure-receiving bodies 51 and 52 and is laminated. The pressure body 50 has a piezoresistance effect.
Further, as shown in FIG. 15, the pressure-sensitive body 50 is made of a composite ceramic material in which a sensor material 508 having a pressure resistance effect is dispersed in a base material 509 made of an electrically insulating ceramic material. . Although various materials can be used as the ceramic material used as the base material 509, zirconia is employed in this example. Various materials can be used as the sensor material 508 having the pressure resistance effect, but (La, Sr) MnO ₃ is used in this example. The load sensor element 5 using the pressure sensitive body 50 is configured to detect only compressive stress.
Of course, any material other than those described above can be used as the pressure-sensitive body 50 as long as the electrical characteristics can be changed according to the received pressure.

Further, as shown in FIG. 13, the pressure receiving bodies 51 and 52 are each made of zirconia, which is a ceramic having electrical insulation. One pressure receiving body 51 has a corner portion 512 provided in an arc shape so as to correspond to the shape of the arc-shaped corner portion 422 of the outer element installation surface 24 described above, and the outer diameter thereof is a pressure-sensitive pressure sensor having a square shape. The body 50 and the other pressure receiving body 52 are configured to be larger.
The load sensor element 5 is formed by laminating the pressure-receiving body 51, the pressure-sensitive body 50, and the pressure-receiving body 52 and integrally firing them, and then performing cutting to finish the shape. It was.

  Next, in assembling the six-axis force sensor 1 of this example, first, as shown in FIG. 10, two load sensor elements 5 are bonded to each of the outer element installation surfaces 24 of the outer member 2. In this example, there are four first outer element installation surfaces 24 (a) and four second outer element installation surfaces 24 (b), a total of eight outer element installation surfaces 24, so the number of load sensor elements 5 is There will be 16 pieces.

  Next, as shown in FIG. 2, the first inner portion 31 and the second inner portion 32 are opposed to each other so as to sandwich the convex portion 29 of the outer member 2, and a spacer member 81 is interposed therebetween. Four inner fastening bolts 82 were fastened to the bolt holes 315, and each load sensor element 5 was sandwiched between the outer element installation surface 24 and the inner element installation surface 34. Further, the inner element installation surface 34 and the pressure receiving body 52 of the load sensor element 5 were bonded with an adhesive interposed therebetween. The spacer member 81 is for controlling a preload condition for applying a predetermined compressive stress to each load sensor element 5 in advance by adjusting the thickness.

Next, as shown in the figure, the shaft portion 62 of the inner fixing portion 6 is inserted into the central hole 316 of the inner member 3, and the central bolt 82 is screwed through the washer 83, so that the inner fixing portion 6 and the inner member 3 Conclude.
Next, the knock pin 85 is inserted into the knock pin insertion hole 26 of the outer member 2 through the knock pin insertion hole 612 of the inner fixing portion 6. The knock pin 85 plays a role of matching the angular phase around the Z axis between the inner fixing portion 6 that is an input portion for 6-axis force and the outer member 2 that is an output portion for 6-axis force.

  And the 6-axis force sensor 1 of such a structure can be fixed to the measured object which is a measuring object of 6-axis force using the outer fixing hole 23 and the inner fixing hole 611 of the outer member 2. .

(Experiment 1)
Next, an experiment for evaluating the performance of the 6-axis force sensor 1 of Example 1 was performed. In order to make the configuration of the six-axis force sensor 1 of the first embodiment easy to understand, as shown in FIGS. 16 to 18, the arrangement of the load sensor elements 5 is modeled in a plane, and reference numerals S _{1 to} S ₁₆ are respectively shown. Was attached. The arrangement of each load sensor element 5 is S ₁ , S ₂ , S ₅ , S ₆ , S ₉ , S ₁₀ , S ₁₃ , S ₁₄ indicating the Fx input angle and S ₃ , S ₄ indicating the Fy input angle. , S ₇ , S ₈ , S ₁₁ , S ₁₂ , S ₁₅ , S ₁₆ are all the same in inclination, and α 1 is 67.5 °. Further, the inclination α2 with respect to S _{1 to} S ₁₆ indicating the Fz input angle is 22.5 °. Further, the long distance L1 from the X axis or Y axis on the reference plane is 12.3 mm, the short distance L2 is 6.8 mm, and the distance L3 from the Z axis is 13.5 mm. Therefore, stress in the X-axis direction is Fx (output), stress in the Y-axis direction is Fy (output), stress in the Z-axis direction is Fz (output), moment about the X-axis is Mx (output), When the moment is My (output), the moment around the Z axis is Mz (output), and the output values of the load sensor elements S _{1 to} S ₁₆ are F _{1 to} F ₁₆ , Equation 1 (Equation 1) can be used.

Here, C in the above equation is a correction matrix C, which is a correction term used when multiaxial interference (crosstalk) occurs, and can be provided as appropriate.
The X-axis direction translation force Fx (input), the Y-axis direction translation force Fy (input), the Z-axis direction translation force Fz (input), and the moment about the X-axis with respect to the six-axis force sensor 1 Mx (input), moment My (input) about the Y-axis, and moment Mz (input) about the Z-axis are added individually, and outputs F ₁ to ₁₆ from all 16 load sensor elements S _{1 to} S ₁₆ F ₁₆ is measured, and all the output values, that is, Fx (output), Fy (output), Fz (output), Mx (output), My (output), and Mz (output) are calculated by the above equation 1. Was measured. The results are shown in FIGS. These form a matrix-like frame with the input type in the horizontal row and the output type in the vertical column, and the horizontal axis indicates the input size and the vertical axis indicates the output size. .

  As can be seen from these figures, the 6-axis force sensor 1 of this example has a sensitivity of approximately 1: 1 output in the same type of direction for the same axis when a translational force or moment is input for each axial direction. In other cases, the output value is almost 0, and it can be seen that the measurement can be performed with very high accuracy.

(Experiment 2)
Next, in order to objectively evaluate the performance of the six-axis force sensor 1 of Example 1, a commercially available strain gauge type multi-axis force sensor was prepared and compared.
As shown in Table 1, the comparison items are shape, volume, translational force rating, moment rating, rigidity, and resonance frequency.

<Shape>
The shape was represented by maximum outer diameter (Φ) × height (h) mm.
<Volume>
The volume is determined by the above ((maximum outer diameter) / 2) ² × π and aligned to the unit of (cc).
<Rigidity>
The rigidity is measured by the amount of deformation generated in the Z-axis direction when the rated Fz is input.
<Resonance frequency>
The resonance frequency is obtained by vibration measurement by a hammering method.

  As is known from Table 1, the 6-axis force sensor 1 of Example 1 is smaller and exhibits higher rigidity than a conventional strain gauge type multi-axis force sensor having a rated value of almost the same rating. I understand. Moreover, it turns out that it has quick responsiveness also from the difference in resonant frequency.

(Example 2)
In this example, as shown in FIGS. 23 to 25, the basic polygonal pyramid that is the basis of the first inner element installation surface, the second inner element installation surface, the first outer element installation surface, and the second outer element installation surface is provided. This is an example of changing to a triangular pyramid. Other configurations are the same as those of the first embodiment.
In this case, as shown in FIGS. 23 to 25, when the arrangement of the load sensor elements 5 is modeled in a plane, the twelve load sensor elements S _{1 to} S ₁₂ are arranged at the positions shown in FIG. Is done. Also in this case, the stress Fx (output) in the X-axis direction and the stress Fy (output) in the Y-axis direction are calculated based on the output values F _{1 to} F ₁₂ from the respective sensors using a modified form of the above-described arithmetic expression 1. , Z-axis direction stress Fz (output), X-axis moment Mx (output), Y-axis moment My (output), and Z-axis moment Mz (output) can be obtained.

  Similarly, the basic polygonal pyramid can be changed to a polygonal pyramid of five or more pyramids other than the triangular pyramid and the quadrangular pyramid. However, it can be said that a 3-8 pyramid is a practical range from a cost or other relationship. In particular, it is most practical to use the quadrangular pyramid of the first embodiment as a basic polygonal pyramid.

FIG. 3 is a plan view of a six-axis force sensor in the first embodiment. The longitudinal cross-sectional view of the 6-axis force sensor in Example 1 (AA arrow directional cross-section and BB arrow directional cross-sectional view of FIG. 1). The top view of the 1st inner part in Example 1. FIG. FIG. 3 is a rear view of the first inner portion in the first embodiment. The longitudinal cross-sectional view (CC sectional view taken on the line CC of FIG. 4) of the 1st inner part in Example 1. FIG. The longitudinal cross-sectional view (DD sectional view taken on the line of FIG. 4) of the 1st inner part in Example 1. FIG. Explanatory drawing which shows the relationship between the 1st polygonal pyramid and the 1st inner side element installation surface in Example 1. FIG. The top view of the outer member in Example 1. FIG. The longitudinal cross-sectional view of the outer member in Example 1 (cross-sectional view taken along line EE in FIG. 8). Explanatory drawing which shows the state which has arrange | positioned the load sensor element in the outer element installation surface of the outer member in Example 1. FIG. The top view of the inner fixing | fixed part in Example 1. FIG. The longitudinal cross-sectional view of the inner fixing | fixed part in Example 1 (FF sectional view taken on the line of FF of FIG. 11). The side view of the load sensor element in Example 1. FIG. FIG. 3 is a plan view of a load sensor element in the first embodiment. FIG. 3 is a model diagram illustrating an internal configuration of a pressure sensor of the load sensor element in the first embodiment. FIG. 3 is an explanatory diagram showing an arrangement of eight load sensor elements located above the reference plane in the first embodiment. FIG. 3 is an explanatory diagram illustrating an arrangement angle of a load sensor element as viewed from a longitudinal section according to the first embodiment. FIG. 3 is an explanatory diagram showing an arrangement of eight load sensor elements located below the reference plane in the first embodiment. Explanatory drawing which shows the measurement result of Fx output, Fy output, and Fz output with respect to Fx input in Example 1, Fy input, and Fz input. Explanatory drawing which shows the measurement result of Fx output, Fy output, and Fz output with respect to Mx input, My input, and Mz input in Example 1. FIG. Explanatory drawing which shows the measurement result of Mx output, My output, and Mz output with respect to Fx input in Example 1, Fy input, and Fz input. Explanatory drawing which shows the measurement result of Mx output, My output, and Mz output with respect to Mx input, My input, and Mz input in Example 1. FIG. Explanatory drawing which shows arrangement | positioning of the six load sensor elements located above the reference plane in Example 2. FIG. Explanatory drawing which shows the arrangement | positioning angle of the load sensor element seen from the longitudinal cross-section in Example 2. FIG. Explanatory drawing which shows arrangement | positioning of the six load sensor elements located in the downward direction from the reference plane in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 6 axial force sensor 2 Outer member 24 (a) 1st outer side element installation surface 24 (b) 2nd outer side element installation surface 3 Inner member 31 1st inner part 32 2nd inner part 34 (a) 1st inner side element installation Surface 34 (b) Second inner element installation surface 5 Load sensor element 71 First polygonal cone 72 Second polygonal cone

Claims (7)

A six-axis force sensor capable of detecting a force in a 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, the Y-axis, and the Z-axis,
An annular outer member centered on a coordinate origin on a reference plane including the X axis and the Y axis;
An inner member having an outer peripheral surface disposed with a gap inside the inner peripheral surface of the outer member;
A plurality of load sensor elements sandwiched between an outer element installation surface provided on the inner peripheral surface of the outer member and an inner element installation surface provided on the outer peripheral surface of the inner member;
The inner element installation surface of the inner member is provided so as to form a recess opposite to both sides across a reference plane including the X axis and the Y axis, and of the inner element installation surface, The plurality of first inner element installation surfaces present on one side across the reference plane correspond to at least a part of the side surface of the first polygonal pyramid having an apex on the Z axis in the reference plane, and the reference plane The plurality of second inner element installation surfaces existing on the other side across the top have a vertex on the Z axis in the reference plane and have the same shape as the second polygonal pyramid facing in the opposite direction to the first polygonal pyramid It is provided to correspond to at least a part of the side surface of
The outer element installation surface of the outer member is provided on both sides of the reference plane including the X-axis and the Y-axis so as to form convex portions accommodated in the recesses in opposite directions, and A plurality of first outer element installation surfaces present on one side of the reference plane between the outer element installation surfaces are arranged substantially parallel to the first inner element installation surface, and the reference plane is defined as A plurality of second outer element installation surfaces present on the other side of the sandwich are arranged substantially parallel to the second inner element installation surface,
Two or more load sensor elements are arranged in one sensor installation region existing between the pair of opposed inner element installation surfaces and the outer element installation surface, respectively. 6-axis force sensor.   2. The load sensor element according to claim 1, wherein the load sensor element comprises a laminate in which a pressure sensitive body is interposed between a pair of electrically insulating pressure receiving bodies, and the pressure sensitive element has a piezoresistive effect. A six-axis force sensor characterized by   3. The polygonal pyramid according to claim 1, wherein the polygonal pyramid is a quadrangular pyramid, and the inner member and the outer member have the inner element installation surface and the outer element installation surface at four circumferential positions around the Z axis, respectively. A six-axis force sensor characterized by comprising:   The six-axis force sensor according to any one of claims 1 to 3, wherein an angle formed between the inner element installation surface and the outer element installation surface with the Z axis is in a range of 10 ° to 80 °. .   5. The inner fixing portion according to claim 1, wherein an inner fixing portion is provided at one axial end portion of the inner member, and the inner fixing portion has an inner diameter of the outer member without being in contact with the outer member. A six-axis force sensor characterized by being formed in a bowl shape having an outer diameter larger than that of the outer diameter.   6. The inner member according to claim 1, wherein the inner member includes a first inner portion provided with the first inner element installation surface and a second inner portion provided with the second inner element installation surface. A six-axis force sensor characterized in that it is manufactured by combining the two.   The spacer member according to any one of claims 1 to 6, wherein the inner member is adjusted in thickness, or the inner member is constituted by a first inner portion and a second inner portion, and is disposed between the two. A six-axis force sensor characterized in that the preload applied to the load sensor element can be adjusted by adjusting the thickness of the load sensor element.

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