JP2001013017A - Load detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a cell block, and to simultaneously achieve superior time and load resolution in a load detector for detecting the amount of deformation of the cell block being elastically deformed according to an applied load for detecting the load. SOLUTION: In the load detector that is equipped with active strain gauges (a) to (d) that detect the amount of deformation of a rectangular parallelpiped block 11 as a cell block, Wheatstone bridge circuits A to D that output the detected amount of deformation as voltage, and a calculation processing part 5 that uses an output value corresponding to the amount of deformation for calculating and for detecting force or moment as a load, the calculation processing part 5 has at least two computing equations using at least two output values for detecting the force or moment, and at the same time shares at least one output value in each computing equation for simultaneously detecting at least bi-directional force or moment, thus eliminating the need for increasing a detection element according to the increase of the direction constituent of the load to be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a load detector,
The present invention relates to a load detector that detects a load by detecting a deformation amount of a cell block that elastically deforms according to an applied load.

[0002]

2. Description of the Related Art Detecting a load acting on an object is indispensable in many industrial fields, and many load detectors for detecting a load (force or moment) in two or more directions have been proposed. Many of the load detectors are configured to determine the load applied to the load detector from the amount of deformation of the elastic portion provided on the load detector. As a means for detecting the amount of deformation of the elastic portion, a method using a strain gauge (electric resistance strain gauge) is generally used.
-85039 and the like. Tokuhei 7-8
Japanese Patent No. 5039 proposes a load detector capable of detecting a force in three axial directions and a moment about three axes. The load detector and the fixed flange are connected by a radial flat plate and a parallel flat plate. It describes that a strain gauge is attached to a predetermined position of the elastic part formed by the above, and that each load is detected by forming a Wheatstone bridge circuit using four strain gauges.

[0003]

By the way, a load detector using a strain gauge usually comprises a Wheatstone bridge circuit using four strain gauges attached to the elastic part as described above. When a load is applied to the detector, the elastic part is deformed and the resistance value of the strain gauge changes.
By utilizing the fact that the equilibrium state of the Wheatstone bridge circuit is broken, an output voltage proportional to the applied load is obtained from the Wheatstone bridge circuit.

However, in the above-described load detectors, the strain gauges are used only for detecting loads in one direction, and in order to detect loads in two or more directions, a load to be detected is required. It is necessary to increase the number of strain gauges attached according to the increase in the number of direction components. Therefore, when the directional component of the load to be detected increases, the elastic portion must necessarily be enlarged. However, when the elastic portion becomes large, the resonance frequency of the load detector decreases, and the time resolution decreases. In order not to lower the time resolution, it is necessary to reduce the elastic modulus of the elastic portion, and it is difficult to achieve both a high time resolution and a high load resolution.

On the other hand, in order to measure the resultant force of the forces acting on the load detector, it is necessary to inner product the forces detected as the component force in each axial direction. However, in a load detector using a strain gauge as a detecting element, the strain gauge is originally
Despite detecting the amount of deformation of the object as the effect of the resultant force, the Wheatstone bridge circuit is composed of four strain gauges, and a mechanism is provided to cancel the effect of the force in the other axial direction. Only the component force is detected, and the detection accuracy of the resultant force acting on the load detector is low.

The present invention has been made in view of such inconvenience, and an object of the present invention is to provide a load detector capable of reducing the size of an elastic portion and achieving both high time resolution and load resolution. And Another object of the present invention is to provide a load detector capable of detecting a resultant force with high accuracy.

[0007]

In order to achieve the above object, a load detector according to the present invention uses, in a calculation processing section, an output value corresponding to a deformation amount detected by at least two detection elements. At least two arithmetic expressions for detecting forces or moments are held, and each arithmetic expression is made to share an output value corresponding to the amount of deformation detected by at least one detecting element, so that forces or moments in at least two directions are simultaneously obtained. It was configured to detect. This eliminates the need to increase the number of detection elements in accordance with an increase in the directional component of the load to be detected, and makes it possible to reduce the size of the cell block provided with the detection elements. Can be provided. Therefore, it is possible to simultaneously detect load components acting on the load detector in two or more directions with high time resolution and load resolution.

Alternatively, the calculation processing unit has a vector operation expression for detecting a force as a vector value using an output value corresponding to the amount of deformation detected by at least two detection elements. Thus, the configuration of the load detector can be simplified, and the resultant can be detected with high accuracy.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a load detector for detecting the amount of deformation of a cell block which elastically deforms in response to an applied load; A plurality of detecting elements, an output circuit for outputting the amount of deformation detected by each detecting element as an electric signal, and a calculation for detecting a force or moment as a load by calculating using an output value from the output circuit. A processing unit, wherein the calculation processing unit has at least two arithmetic expressions for detecting a force or a moment using at least two of the output values, and shares at least one of the output values for each arithmetic expression. Thus, at least two forces or moments can be simultaneously detected.

According to a second aspect of the present invention, in the configuration of the first aspect, the cell block has a plate-shaped elastic portion, and two opposite sides of the elastic portion have detecting elements for measuring the amount of deformation of the surface. It is characterized by being provided. According to a third aspect of the present invention, in the configuration according to the first aspect, the detection element is a strain gauge, and the output circuit includes at least two Wheatstone bridge circuits, and the strain gauge is at least one for each Wheatstone bridge circuit. It is characterized by being provided.

According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, the calculation processing unit comprises:
The temperature correction is performed by performing an addition / subtraction operation on output values corresponding to at least two detection elements. The invention according to claim 5 is a load detector that detects an amount of deformation of a cell block that elastically deforms according to an applied load and detects the load, wherein a plurality of detection elements that detect an amount of deformation of the cell block; An output circuit that outputs the amount of deformation detected by each detection element as an electric signal, and a calculation processing unit that detects a force or moment as a load by calculating using an output value from the output circuit, The calculation processing unit is configured to have a vector operation expression for detecting a force as a vector value using at least two of the output values.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect, the calculation processing unit has an arithmetic expression for separating a force detected as a vector value into a force in at least two directions. According to a seventh aspect of the present invention, in the configuration according to the fifth or sixth aspect, the cell block is formed in a triangular prism shape, and a detection element for measuring a deformation amount of the surface is provided on three side surfaces. It is characterized by having been done.

According to an eighth aspect of the present invention, in the configuration of the fifth or sixth aspect, the cell block is formed in a triangular pyramid shape, and at least three side surfaces are measured for the amount of deformation of the surface. A detection element is provided. According to a ninth aspect of the present invention, in the configuration according to any one of the fifth to eighth aspects, the detection element is a strain gauge, the output circuit includes at least two Wheatstone bridge circuits, and the strain gauge is At least one Wheatstone bridge circuit is provided.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. (Embodiment 1) FIG. 1 is a simplified overall configuration diagram showing a load detector according to Embodiment 1 of the present invention, and FIG. 2 is a schematic perspective view showing a load detector in the load detector. In the load detector shown in FIG. 1, the load detecting unit 1 is provided with active strain gauges a, b, c, and d as detecting elements.
b, c, d, and three of the resistors (or dummy strain gauges) r1 to r12 as electric circuit elements, respectively, are Wheatstone bridge circuits A,
B, C, and D are configured.

The load detector also includes a voltage section 2 for applying a voltage to each of the Wheatstone bridge circuits A, B, C, and D, and an output signal from each of the Wheatstone bridge circuits A, B, C, and D, respectively. Amplifier units 3A, 3B,
3C, 3D and A / D converters 4A, 4B, 4C, 4D
And the amplifier units 3A to 3D and the A / D converters 4A to 4A.
Calculation processing unit 5 that records the output signal that has passed through 4D and performs an operation
And an interface 6 for transmitting a load obtained as a calculation value by the calculation processing unit 5 to an external device.

As shown in FIG. 2, the load detecting section 1 has the active strain gauges a, b, c, and d as the above-described detecting elements attached to a rectangular parallelepiped block 11 preferably made of a metal material such as an aluminum alloy. It was worn.
Here, the name of each coordinate in the load detection unit 1 is Z-axis in the vertical direction along the paper surface, X-axis in the left-right direction along the paper surface,
An axis perpendicular to both the X axis and the Z axis is defined as a Y axis.

The rectangular parallelepiped block 11 is provided with a through-hole 12 whose axis extends along the Y-axis, and the elastic portion 13 and the elastic portion 1 having a flat plate structure are provided between the through-hole 12 and the outer peripheral surface of the block along the Y-axis.
4 are formed. The rigid portion formed between the through hole 12 and the upper surface of the block is a fixed side flange 16,
The rigid portion formed between the block 2 and the lower surface of the block is a measurement-side flange 17.

The active strain gauges a to d are respectively attached to the stress concentration portions on the outer peripheral surface of the elastic portion 13 and the elastic portion 14 at intervals in the direction along the Y-axis. Is applied, the resistance value changes according to the amount of deformation of the elastic portions 13 and 14 in the Z-axis direction. Therefore, when the bonded portions of the active strain gauges a to d in the elastic portion 13 and the elastic portion 14 are deformed, the amounts of the deformation are detected by the active strain gauges a to d, respectively, as output voltages from the Wheatstone bridge circuits A to D. Obtained independently.
The output voltages of the Wheatstone bridge circuits A to D are amplified by the amplifier units 3A to 3D, converted into digital signals by the A / D converters 4A to 4D, and sent to the calculation processing unit 5. Here, the Wheatstone bridge circuit A,
The output voltages sent from B, C and D to the calculation processing unit 5 are defined as E1, E2, E3 and E4, respectively.

The output when a load in each direction acts on the measurement side flange 17 with the rectangular parallelepiped block 11 fixed on the fixed side flange 16 will be described below.
When a force in the positive direction of the X axis acts on the measurement-side flange 17, output voltages corresponding to the elongation strain are obtained as E1 and E2, and output voltages corresponding to the compression strain are obtained as E3 and E4. When a counterclockwise moment acts on the measurement side flange 17 as viewed from the positive direction of the X axis, E
The output voltage corresponding to the elongation strain as E1 and E3, E2
As E4 and E4, an output voltage corresponding to the compression strain is obtained. When a counterclockwise moment acts on the measurement side flange 17 as viewed from the positive direction of the Z axis, E1 and E1
Output voltage according to compression strain as E4, E2 and E3
As a result, an output voltage corresponding to the elongation strain is obtained. When a force in the positive direction of the Z-axis acts on the measurement-side flange 17, an output voltage corresponding to the elongation strain is obtained in all of E1 to E4.

Therefore, the calculation processing unit 5 calculates the output voltages E1 to E4 in accordance with the deformation amounts of the elastic parts 13 and 14 to which the active strain gauges a to d are adhered, thereby acting on the measurement side flange 17. The applied load can be measured separately. In the first embodiment, force (F) or moment (M) in four directions is detected using the following four arithmetic expressions. Fx = α1 (E1 + E2-E3-E4) (1) Mx = α2 (E1-E2 + E3-E4) (2) Mz = α3 (E1-E2-E3 + E4) (3) Fz = α4 (E1 + E2 + E3 + E4) ( 4) Fx in the X-axis direction using equation (1), moment Mx around the X axis using equation (2), moment Mz about the Z axis using equation (3), equation (4) Is used to detect the force Fz in the Z-axis direction. Note that α1 to α4 used in the equations (1) to (4) are coefficients for converting the output voltage and the force or the moment, and are determined at the time of the initial calibration of the load detector. Each arithmetic expression cancels the influence of the load in the other direction by performing an addition / subtraction operation on the output voltage, and the load in each direction can be accurately detected.

As described above, in the load detector according to the first embodiment, only four active strain gauges are attached to the elastic portions 13 and 14. On the other hand, in a conventional load detector, that is, a single Wheatstone bridge circuit using four active strain gauges and detecting a force or moment in one direction, a force in two directions and two forces are used.
In order to detect the moment around the direction, it was necessary to attach 16 active strain gauges to the elastic part.

Therefore, the configuration of the first embodiment makes it possible to reduce the size of the elastic portions 13 and 14 as compared with the prior art. As a result, it becomes possible to increase the resonance frequency of the load detecting portion 1 and increase the time required for the operation. Resolution is obtained. Regarding the load resolution and load detection accuracy, since the force or moment in one direction is detected by calculating the output voltage from the four active strain gauges, the force in one direction is detected using the four active strain gauges. Is equivalent to detecting the

When the active strain gauge is provided, it is usually attached to the stress concentration portions of the elastic portions 13 and 14, and high attachment accuracy is required. Since the number can be reduced to four, the production of the load detector becomes easy. Active strain gauge a ~
The effect of temperature on d will be described. Since the rectangular parallelepiped block 11 is formed of a single metal material, the coefficient of thermal expansion is uniform, and therefore, the coefficients of expansion of the active strain gauges a to d due to temperature changes are the same,
The amount of change in the resistance value of the active strain gauges a to d due to temperature change, and further, the Wheatstone bridge circuits A to D
Are the same. Formula (1) to
In equation (3), four Wheatstone bridge circuits A to
In D, since the output voltages from the other two Wheatstone bridge circuits are subtracted from the output voltages from the two Wheatstone bridge circuits, the amount of change in the output voltage due to the temperature change is canceled, and the temperature-corrected load Detection is possible. (Embodiment 2) The load detector 31 shown in FIG. 3 has substantially the same configuration as the load detector 1 described above with reference to FIG. ing. That is, active strain gauges a3, b
Reference numerals 3, c3, and d3 are attached to the vicinity of the center of the stress concentration portions of the elastic portions 13 and 14 at intervals in the direction along the Z axis.

These active strain gauges a3-d
3, Wheatstone bridge circuits A3, B3, C similar to those described above with reference to FIG.
3, D3, and is configured to obtain an output voltage corresponding to the amount of deformation of the sticking portion in the Z direction.
Here, Wheatstone bridge circuits A3, B3, C
3 and D3, the output voltages sent to the calculation processing unit 5 are defined as EA3, EB3, EC3, and ED3, respectively.

The output when a load in each direction acts on the measurement side flange 17 with the rectangular parallelepiped block 11 fixed on the fixed side flange 16 will be described below.
When a force acts on the measurement side flange 17 in the positive direction of the X-axis, an output voltage corresponding to the compression strain is obtained as EA3 and ED3, and an output voltage corresponding to the extension strain is obtained as EB3 and EC3. When a counterclockwise moment acts on the measurement side flange 17 as viewed from the positive direction of the Y axis, the output voltage corresponding to the elongation strain as EA3 and EB3 and the output voltage corresponding to the compression strain as EC3 and ED3. can get. When a force in the positive direction of the Z-axis acts on the measurement side flange 17, EA3, EB3, EC
3. An output voltage corresponding to the elongation strain can be obtained in all of ED3.

Therefore, in the calculation processing section 5, the elastic sections 13, 14 to which the active strain gauges a3 to d3 are attached are attached.
By calculating the output voltages EA3 to ED3 in accordance with the amount of deformation, the load applied to the measurement-side flange 17 can be separately measured. In the second embodiment, force (F) or moment (M) in three directions is detected using the following three arithmetic expressions.

Fx = α5 (EA3-EB3-EC3 + ED3) (5) My = α6 (EA3 + EB3-EC3-ED3) (6) Fz = α7 (EA3 + EB3 + EC3 + ED3) (7) By using the expression (5), X is obtained. The axial force Fx, the moment My around the Y axis by using the equation (6), and the force Fz in the Z axis direction by using the equation (7) can be detected. Note that α5 to α7 used in the equations (5) to (7) are coefficients for converting the output voltage and the force or the moment, and are determined at the time of the initial calibration of the load detector. Each arithmetic expression cancels the effect of the load in the other direction by performing the addition / subtraction operation on the output weight pressure, and the load in each direction can be accurately detected. (Embodiment 3) The load detecting section 51 shown in FIG. 5 is formed by attaching active strain gauges a5 and b5 to the front and back central portions of an elastic portion 51a in the form of a cantilever having an upper portion fixed. The upper part of the beam was a fixed-side flange 56 and the lower part was a measurement-side flange 57.

These active strain gauges a5, b
As shown in FIG. 6, 5 is incorporated in the same Wheatstone bridge circuits A5 and B5 as described above with reference to FIG. 1, and the output pressure corresponding to the amount of deformation of the sticking position in the Z direction is reduced. It is configured to be obtained. Here, the output voltages sent from the Wheatstone bridge circuits A5 and B5 to the calculation processing unit 5 are defined as EA5 and EB5, respectively.

The output when a load in each direction acts on the measurement side flange 57 with the elastic portion 51a fixed on the fixed side flange 56 will be described. Measurement side flange 57
When a force acts in the positive direction of the X-axis, an output voltage corresponding to the compressive strain is obtained as EA5, and an output voltage corresponding to the elongation strain is obtained as EB5. When a force acts on the measurement side flange 57 in the positive direction of the Z axis, EA5, EB
5, an output voltage corresponding to the compression strain is obtained.

Therefore, the calculation processing unit 5 calculates the output voltages EA5, EB5 according to the deformation amount of the elastic part 51a to which the active strain gauges a5, b5 are attached, thereby obtaining the load applied to the measurement side flange 57. Can be measured separately. In the third embodiment, force in two directions is detected using the following two arithmetic expressions. Fx = α8 (EA5-EB5) (8) Fz = α9 (EA5 + EB5) (9) Force Fx in the X-axis direction by using equation (8) and force in the Z-axis direction by using equation (9) Fz can be detected. Note that α8 and α9 used in equations (8) and (9) are coefficients for converting the output voltage and the force or moment, and are determined at the time of the initial calibration of the load detector.

Note that the load detecting unit is the same as that of the first embodiment.
The present invention is not limited to the structures as described above, and can be arbitrarily changed. (Embodiment 4) FIG. 7 is a simplified overall configuration diagram showing a load detector according to Embodiment 4 of the present invention, and FIG. 8 is a schematic perspective view showing a load detector in the load detector.

In the load detector shown in FIG. 7, the load detecting section 71 is provided with active strain gauges a7, b7, and c7 as detecting elements, and any one of these active strain gauges a7, b7, and c7 is provided. One and three of the resistors (or dummy strain gauges) r1 to r9 as electric circuit elements constitute Wheatstone bridge circuits A7, B7, and C7, respectively.

This load detector also includes a voltage section 2 for applying a voltage to each of the Wheatstone bridge circuits A7, B7, C7, and a Wheatstone bridge circuit A7, B7, C
Amplifiers 3A, 3B, 3C that amplify the output signal from
And A / D converters 4A, 4B, and 4C, a calculation processing unit 5 that records the output signals that have passed through the amplifier units 3A to 3C and the A / D converters 4A to 4C, and performs a calculation. An interface 6 for transmitting a load obtained as a value to an external device is provided.

As shown in FIG. 8, the load detecting section 71
The active strain gauges a7, b7, and c7 as the above-described detection elements are adhered to a regular triangular prism block 72 preferably made of a metal material such as an aluminum alloy. Here, the name of each coordinate in the load detection unit 71 is defined as a Z-axis in the vertical direction along the plane of the paper, an X-axis in the horizontal direction along the plane of the paper, and a Y-axis as an axis perpendicular to both the X-axis and the Z-axis. Determine.

The upper part of the equilateral triangular prism block 72 is a fixed flange 76, and the lower part is a measuring flange 77. Active strain gauges a7 to c7 are equilateral triangular prism blocks 7.
2 are attached to substantially the center of each side surface, and when a force is applied to the measurement-side flange 77, the resistance value according to the amount of deformation in the Z-axis direction of the attachment site of each of the active strain gauges a7 to c7. Changes.

These active strain gauges a7 to c
7 are independent Wheatstone bridge circuits A
7 to C7, the amounts of deformation of the attached portions of the active strain gauges a7 to c7 are independently obtained as output voltages from the Wheatstone bridge circuits A7 to C7. The output voltages of the Wheatstone bridge circuits A7 to C7 are amplified by the amplifier units 3A to 3D, converted into digital signals by the A / D converters 4A to 4C, and sent to the calculation processing unit 5. Here, the output voltages sent from the Wheatstone bridge circuits A7, B7, C7 to the calculation processing unit 5 are defined as EA7, EB7, EC7, respectively.

Hereinafter, with the equilateral triangular prism block 72 fixed on the fixed side flange 76, the measurement side flange 77
With reference to FIG. 9, the output values when the loads in the respective directions act on. FIG. 9 is a plan view of the regular triangular prism block 72 viewed from the positive direction of the Z axis. Here, the regular triangular prism block 7
From the center of 2, the normal direction of the side surface on which the active strain gauge a7 is stuck is the l-axis, the normal direction of the side surface on which the active strain gauge b7 is stuck is the m-axis, and the side surface on which the active strain gauge b7 is stuck. Is defined as the n-axis.

When a positive force of the l-axis is applied to the measurement side flange 77, an active strain gauge a7 detects an elongation strain proportional to the magnitude of the force, and b7 and c7 detect a compression strain. When a force in the positive direction of the m-axis is applied, the active strain gauge b7 detects an elongation strain proportional to the magnitude of the force, and a7 and c7 detect a compression strain. When a force in the positive direction of the n-axis is applied, the active strain gauge c7 detects an elongation strain proportional to the magnitude of the force, and a7 and b7 detect a compression strain. L to n
When the force in the negative direction of the shaft acts, the strain in the opposite direction to that in the case where the force in the positive direction acts is detected by each of the active strain gauges a7 to c7. The amount of deformation detected by each of the active strain gauges a7 to c7 is transmitted from the Wheatstone bridge circuits 3A to 3C to the calculation processing unit 5 as an output voltage proportional to the force in each of the coordinate axes l to n. Here, the Wheatstone bridge circuits A7, B
7, EA7, EB7, EC
Determined as 7.

Therefore, the calculation processing unit 5 uses the output voltages EA7 to EC7 corresponding to the deformation amounts of the active strain gauges a7 to c7 in accordance with the deformation amount, and calculates the inner product according to the equation (10). The measurement side flange 77
Can be detected as a vector value. Note that α10 used in the equation (10) is a coefficient for converting the output voltage and the force, and is obtained by the initial calibration of the load detector.

F = α10 · EA7 · EB7 · EC7 (10) When a force acts on the measurement-side flange 77 in the positive direction of the Z-axis, the active strain gauges a7 to c7 compress the strain.
When a negative force is applied, the active strain gauges a7 to c7 detect extensional strain. However, since the deformation amounts detected by the active strain gauges a7 to c7 are the same, the equation (10) is used. By performing the calculation, the output component due to the force in the Z-axis direction is canceled.

The unit vector in the X-axis direction is ix, Y
Assuming that the unit vector in the axial direction is iy, the following equation (1)
1) According to equation (12), the force F obtained by equation (10)
Can be separately measured as component forces in the X-axis and Y-axis directions. Fx = F · ix (11) Fy = F · iy (12) As can be seen from the above, by configuring the load detector as in the fourth embodiment, the configuration of the load detector is simplified. In addition, the resultant force can be detected with high accuracy. Also,
The component force in each axial direction can also be easily obtained by performing a simple calculation on the resultant force. On the other hand, in the conventional load detector, despite the fact that the strain gauge originally detects the amount of deformation of the object as the action of the resultant force, the Wheatstone bridge circuit is configured with four strain gauges, A mechanism to cancel the action of the force of
The resultant force of the force acting on the load detector was measured by detecting the component force in each axial direction and scalarizing the detected component force.
In other words, it can be said that the configuration of the load detector was bothersomely complicated, and the detection accuracy of the resultant force acting on the load detector was reduced.

In the load detector according to the fourth embodiment, the resultant force is first detected, so that it is not necessary to cancel the influence of the force in the other direction by the configuration of the load detector.
Therefore, it is not necessary to attach a high-precision active strain gauge, and the production of the load detector becomes easy. In contrast, with conventional load detectors, the effect of forces in other directions must be canceled by the configuration of the load detector to detect the component force in each axial direction. It had to be done with precision.

In the fourth embodiment, the load detector 7
Although the regular triangular prism block 72 is used for 1, the present invention is not limited to this, and any triangular prism can be used. (Embodiment 5) In the schematic perspective view of the load detecting section 101 shown in FIG. 10, reference numeral 102 denotes a triangular pyramid, preferably made of a metal material such as an aluminum alloy, whose upper surface is a regular triangle and whose other three sides are isosceles triangles. The upper part of the triangular pyramid is a fixed side flange 106 and the lower part is a measurement side flange 10.
7 is set. Active strain gages a10, b1
The reference numerals 0 and c10 are attached to substantially the center of the isosceles triangle, and a resistance value change proportional to the amount of deformation of the isosceles triangle forming each side in the direction of the symmetry line is obtained. Here, the name of each coordinate in the load detection unit 101 is Z axis in the vertical direction along the paper surface, X axis in the left and right direction along the paper surface, and X axis and Z axis.
The axis perpendicular to any of the axes is defined as the Y axis.

Active strain gauges a10 to c1
0 is a Wheatstone bridge circuit A10, B1 similar to that described above with reference to FIG.
0, C10 so that an output voltage proportional to a change in resistance value can be obtained. Hereinafter, an output when a load in each direction acts on the measurement side flange 107 in a state where the triangular pyramid block 102 is fixed on the fixed side flange 106 will be described. Here, in the same manner as shown in FIG. 9, the inward in the normal direction of the side surface on which the active strain gauge a7 is attached is the o-axis, and the inward direction in the normal direction of the side surface on which the active strain gauge b7 is attached. The p-axis and the inward in the normal direction of the side surface on which the active strain gauge b7 is stuck are defined as the q-axis.

When a force in the positive direction of the o-axis is applied to the measurement side flange 107, an active strain gauge a10 detects an elongational strain proportional to the magnitude of the force, and the active strain gauges b10 and c10 detect a compressive strain. . When a force in the positive direction of the p-axis is applied, the active strain gauge b10 uses an elongation strain proportional to the magnitude of the force, a10,
At c10, a compression strain is detected. When a force in the positive direction of the q-axis is applied, an elongation strain proportional to the magnitude of the force is detected by the active strain gauge c10, and a compression strain is detected by a10 and b10. When a force in the negative direction of each of the o to q axes acts, the respective active strain gauges a10
In steps c10 to c10, a strain in a direction opposite to that in the case where a forward force is applied is detected. Each active strain gauge a10-c
The amount of deformation detected at 10 is transmitted from each of the Wheatstone bridge circuits A10, B10, and C10 to the calculation processing unit 5 as an output voltage proportional to the force in each of the coordinate axes o to q. Here, the Wheatstone bridge circuits A10, B
The outputs from C10 and C10 are EA10 and EB1 respectively.
0, EC10.

Therefore, the calculation processing unit 5 uses the output voltages EA10 to EC10 corresponding to the deformation amounts of the active strain gauges a10 to d10 to calculate the inner product according to the equation (13). Thus, the force acting on the measurement side flange 107 can be detected as a vector value. Note that α10 used in the equation (13) is a coefficient for converting the output voltage and the force, and is obtained by the initial calibration of the load detector.

F = α13 · EA10 · EB10 · EC10 (13) Further, if a unit vector in the X-axis direction is ix, a unit vector in the Y-axis direction is iy, and a unit vector in the Z-axis direction is iz, equation (13) Can be separated and measured as the component force in the X-axis direction, the Y-axis direction, and the Z-axis direction by the following equations (14), (15), and (16).

Fx = F · ix (14) Fy = F · ii (15) Fz = F · iz (16) In the first to fifth embodiments, a strain gauge is used as a detecting element. The detection element can be used without being limited to the strain gauge as long as it can detect the deformation amount of the object.

In the first to fifth embodiments, the output of the strain gauge as a detecting element is converted to a voltage using a Wheatstone bridge circuit. However, if the output of the strain gauge can be converted to a voltage, the output is converted to a Wheatstone bridge circuit. It can be used without limitation.

[0050]

As described above, according to the present invention, the calculation for detecting the force or moment using the output value corresponding to the amount of deformation detected by at least two detecting elements is performed in the calculation processing unit of the load detector. By holding at least two expressions and sharing the output value corresponding to the amount of deformation detected by at least one detection element with each arithmetic expression, it is configured to simultaneously detect forces or moments in at least two directions. Accordingly, it is not necessary to increase the number of detection elements in accordance with an increase in the directional component of the load to be detected, and the cell block provided with the detection elements can be reduced in size, and the following effects can be obtained.

(1) The resonance frequency can be increased, and a high time resolution can be obtained. (2) The same load resolution and load detection accuracy as before can be secured without increasing the number of detection elements. (3) The number of detection elements requiring high-precision attachment can be reduced, and the production of a load detector is facilitated.

(4) Load detection with temperature correction is possible. In addition, at least 2
By holding a vector operation expression for detecting a force as a vector value using an output value corresponding to the deformation amount detected by one of the detection elements, the following effects can be obtained. (5) The configuration of the load detector can be simplified.

(6) It is possible to detect the resultant force with high accuracy,
The component force in each axial direction can also be easily obtained by performing a simple calculation on the force obtained as the resultant force. (7) It is not necessary to attach the active strain gauge with high precision, and the production of the load detector becomes easy.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a load detector according to Embodiment 1 of the present invention.

FIG. 2 is a schematic perspective view of a load detector according to the first embodiment.

FIG. 3 is a schematic perspective view of a load detector according to Embodiment 2 of the present invention.

FIG. 4 is an overall configuration diagram according to the second embodiment.

FIG. 5 is a schematic perspective view of a load detector according to Embodiment 3 of the present invention.

FIG. 6 is an overall configuration diagram according to the third embodiment.

FIG. 7 is an overall configuration diagram of a load detector according to Embodiment 4 of the present invention.

FIG. 8 is a schematic perspective view of a load detector according to the fourth embodiment.

FIG. 9 is a plan view of a load detector according to the fourth embodiment.

FIG. 10 is a schematic perspective view of a load detector according to Embodiment 5 of the present invention.

FIG. 11 is an overall configuration diagram according to the fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Load detection part a-d Active strain gauge (detection element) A-D Wheatstone bridge circuit (output circuit) 5 Calculation processing part 11 Rectangular block (cell block) 13,14 Elastic part 72 Regular triangle block (cell block) 102 triangle Cone block (cell block)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Koji Taniguchi 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kaoru Matsuoka 1006 Kadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial F Term (reference) 2F049 AA12 BA04 BA06 CA01 CA05 CA09 CA11 DA01

Claims (9)

[Claims] 1. A load detector for detecting the amount of deformation of a cell block elastically deformed according to an applied load and detecting the load, wherein a plurality of detection elements for detecting the amount of deformation of the cell block; An output circuit that outputs each of the deformation amounts detected in the above as an electric signal, and a calculation processing unit that detects a force or moment as a load by calculating using an output value of the output circuit. The unit holds at least two arithmetic expressions for detecting a force or a moment using at least two of the output values, and shares at least one of the output values for each of the arithmetic expressions so as to generate a force or a moment in at least two directions. A load detector characterized in that the load detector can be simultaneously detected. 2. The cell block has a flat elastic portion,
The load detector according to claim 1, wherein a detection element that measures an amount of deformation of the elastic portion is provided on two opposite sides of the elastic portion. 3. The sensor according to claim 1, wherein the detecting element is a strain gauge, the output circuit includes at least two Wheatstone bridge circuits, and at least one strain gauge is provided for each of the Wheatstone bridge circuits. Load detector as described. 4. The apparatus according to claim 1, wherein the calculation processing unit is configured to perform temperature correction by performing an addition / subtraction operation on output values corresponding to at least two detection elements. Load detector as described. 5. A load detector for detecting the amount of deformation of a cell block elastically deformed according to an applied load and detecting the load, wherein a plurality of detecting elements for detecting the amount of deformation of the cell block; An output circuit that outputs each of the deformation amounts detected in the above as an electric signal, and a calculation processing unit that detects a force or moment as a load by calculating using an output value of the output circuit. The unit has a vector operation expression that detects a force as a vector value using at least two of the output values. 6. The load detector according to claim 5, wherein the calculation processing unit has an arithmetic expression for separating a force detected as a vector value into a force in at least two directions. 7. The cell block is formed in a triangular prism shape.
7. The load detector according to claim 5, wherein a detection element for measuring a deformation amount of the surface is provided on one of the side surfaces. 8. The cell block is formed in a triangular pyramid shape.
7. The load detector according to claim 5, wherein a detection element for measuring a deformation amount of one of the side surfaces is provided. 9. The sensor according to claim 5, wherein the detection element is a strain gauge, and the output circuit includes at least two Wheatstone bridge circuits, and at least one strain gauge is provided for each of the Wheatstone bridge circuits. The load detector according to any one of claims 1 to 8.