JPS61237029A - Multi-direction force detector - Google Patents

Abstract

PURPOSE:To detect force in three ways and moments therearound in three ways, by arranging spacers in a detector unit formed in a Roberval's parallel motion mechanism in a cross so as to be orthogonal to each other in a hollow part of other detectors. CONSTITUTION:When a force Fx vertical to an X-way plate spring 7 works on a load flange 2, the force Fx trasmits sequentially to Y-way plate springs 6 and 6a, a cross spacer 5 and X-way plate springs 7 and 7a through a spacer 3. Here, as a spacer 4, the plate springs 6 and 6a and the spacer 5 in the transmission path of the force, the deflection thereof having a sufficient rigidity with respect to the force Fx is very limited and in stead, the plate spring 7 alone having no enough rigidity causes a bend distortion, with the result that an output is drawn from a bridge circuit of a strain gauge 9 stuck on the plate spring 7. When a moment Mx around the force Fx works on the flange 2, a lateral spacer 5b of the cross spacer 5 parallel with the force Fy causes a bend distortion and the moment Mx is detected with a bridge circuit of a strain gauge 11 stuck on the lateral spacer 5b. The forces in the ways Y and Z are detected likewise.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multidirectional detector that detects forces in six directions, including forces in orthogonal X, Y, and Z directions and moments around these directions. It is.

(Prior art and problems) Conventionally, in order to detect forces in six directions, six strain-generating bodies that are easily deflected by forces in three orthogonal directions and moments around these directions are used, and the strain-generating bodies are Attach a strain gauge to a position of the body where the bending is large, or carve out a single block of metal or the like to form a part that is easily deflected by forces in three directions and moments around these directions.
The output is obtained by attaching a strain gauge.

However, the former detector has a problem in that it has a large number of strain-generating bodies, making the entire detector large and complex, making it difficult to connect the strain-generating bodies. In addition, in the latter detector, all the bending parts are connected, so for force in the - direction, there is a strain gauge that detects not only that force but also a strain gauge that detects force in other directions. is also output as crosstalk. For this reason, it is necessary to eliminate this crosstalk, and since calibration is performed in advance to determine a calibration constant, and arithmetic processing is performed via this calibration constant, there is a problem that output cannot be performed in real time. be.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, has a compact configuration, and can output not only forces in the X, Y, and Z directions, but also moment forces around each direction in real time. The purpose is to provide a multidirectional force detector that can - (Summary of the invention) In order to achieve the above object, the multidirectional force detector according to the present invention is configured into a so-called donkey-pal mechanism by attaching highly rigid spacers to both ends of two parallel leaf springs. The spacer of each detector unit penetrates the hollow part of the other detector unit orthogonally, and the spacers that have passed through the spacer intersect in a cross shape. X on the spacers and the leaf springs that are integrated with each other and intersect in a criss-cross pattern.

It is characterized by being equipped with a stress detection element that detects forces in the Y and Z directions and a moment detection element that detects moments around these directions.

(Example) Hereinafter, a multidirectional force detector according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view of one embodiment of the present invention, and FIG. 2 is a perspective view of the assembled state. The detector of this embodiment includes a disk-shaped fixed flange 1, a disk-shaped load flange 2 on which force acts, and a first flange disposed between these flanges 1 and 2.
and a second detector unit. The first detector unit includes two parallel leaf springs 7, 7a located above and below, a spacer 3 fixed to the left end of the leaf springs 7, 7a by a plate 14 and a screw 15, and a spacer 3 fixed to the right end of the leaf springs 7, 7a. It consists of a cross-shaped spacer 5 fixed to. Here, the cross-shaped spacer 5 is composed of a vertical spacer 5a and a horizontal spacer 5b that is attached by screws or welding in the front and rear horizontal direction so as to be orthogonal to the vertical spacer 5a. It is connected to leaf springs 7, 7a. Therefore, the leaf springs 7, 7a, the spacer 3, and the vertical spacer 5a of the cross-shaped spacer 5 form a zero-bappal mechanism. In this donkey pal mechanism, the rigidity of the spacer 3.5a is sufficiently higher than that of the leaf spring 7, so that the spacer 3.5a is less susceptible to deflection. Further upward leaf spring 7
Four stress detecting elements 9 such as strain gauges are attached to two places on the front and back surfaces of the sensor, and a bridge circuit is formed between the stress detecting elements 9 to eliminate the influence of moment. This stress detection element 9 has a force F in the X direction as described later.
This is to detect X.

The second detector unit includes two leaf springs 6.6a located in the front-rear direction, a spacer 4 with high rigidity attached horizontally to the right end of the leaf springs 6, 6a, and the first detector unit.
The horizontal spacer 5b of the cross-shaped spacer 5 is connected to the left end of the leaf spring 6.degree. 6a. Therefore, this detector unit also has a donkey-pal mechanism, but the cross-shaped spacer 5 is located inside the spacers 3 and 4, and the vertical spacer 5a and the horizontal spacer 5b are located on the outside spacer 3.4. On the other hand, it is an inner spacer located on the inner side. In addition, four stress detection elements 8 such as strain gauges with bridge circuits formed are pasted on two places on the front and back surfaces of the front leaf spring 6 among the leaf springs, and detect the force F in the Y direction. Note that the connection between the leaf springs 6, 6a and the spacers 4 and 5b is performed via the plate 14 and the screw 15, similarly to the first detector unit.

The fixing flange 1 is attached to the spacer 3 on the outside of the first detector unit, and the load flange 2 is attached to the spacer 4 on the outside of the second detector unit by screws 16, respectively. Four stress detecting elements 10 such as strain gauges forming a bridge circuit are attached to the upper and lower surfaces of the cross-shaped spacer 5 inside these outer spacers 3.4 located before and after the vertical spacer 5a. force Fz in two directions is detected. Furthermore, this vertical spacer 5a
Moment detection elements 12 for detecting the moment My around the Y direction are attached to the top and bottom of the surfaces located on the left and right sides of the horizontal spacer 5b. A moment detection element 11 for detecting moment MX is attached. Moment detection elements 13 for detecting moments Mz in two directions are attached to the front and rear surfaces of the continuous portion where the vertical spacer 5a and the horizontal spacer 5b intersect in a cross shape. For each of these moment detection elements 11, 12, and 13, strain gauges are used like the stress detection elements, and four strain gauges forming a bridge circuit are attached at symmetrical positions for each moment detection element. It is something.

In addition, among such moment detection elements, moment MX
.

The strain gauge 11.12 that detects My is a force 1”z in two directions.
A bridge circuit is formed to eliminate this bending strain, and a bridge circuit is formed to detect torsional strain in the strain gauge 13 that detects the moment Mz.

Furthermore, notches 3 are formed in the inner surfaces of the spacers 3 and 4 located on the outer side, which face the inner cross-shaped spacer 5.
a, 4a are formed respectively, and a vertical spacer 5a and a horizontal spacer 5b of the cross-shaped spacer 5 are formed in the notches 3a, 4a.
are inserted at intervals. As a result, when an overload is applied, the inner spacer cuts out the notch 3a of the outer spacer.

4a, it can be used as a stopper, and the displacement in the longitudinal direction of each stress detection element installed in the leaf spring in the X direction and the Y direction can be reduced, and the force detection error can be reduced. , the overall length of the detector is also shorter.

Next, forces FX, FV in three orthogonal directions of X, Y, and Z are generated by this embodiment configured as described above.

The operation of detecting Fz will be explained.

When a force Fx in a direction perpendicular to the X-direction leaf spring 7 acts on the load flange 2, the force 4FX is applied to the Y-direction through the spacer 4.
It is transmitted in order to the direction leaf spring 6.6a, the cross-shaped spacer 5, and the X direction leaf spring 7.7a. At this time, the spacer 4, the Y-direction leaf springs 6, 6a, and the cross-shaped spacer 5 in the force transmission path have sufficient rigidity against the force Fx, so the deflection is so small that it can be ignored. Bending strain occurs only in the X-direction leaf spring 7, which does not have sufficient rigidity for FX, and as a result, the bridge circuit of the strain gauge 9 attached to the X-direction leaf spring 7 loses its balance. Output is retrieved.

Further, when a force Fy in a direction perpendicular to the leaf spring 6 in the Y direction acts on the load flange 2, the force Fy is applied to the leaf spring 6-6 a in the Y direction via the spacer 4, as in the case of the force Fx.
It is transmitted in order to the s+ cross-shaped spacer and the X-direction leaf springs 7 and 7a, but the spacer 4. Since the cross-shaped spacer 5 and the X-direction leaf spring 7°7a have sufficient rigidity against the force Fy, the deflection is so small that it can be ignored, and therefore, they have sufficient rigidity against the force Fy. Only the Y-direction leaf spring 6 that is not in the
The bridge circuit of the strain gauge 8b attached to the directional plate spring 6 is unbalanced, and an output is taken out. and,
The detection positions of such forces 1"x and Fy are both short distances from the force load position and the influence of moment can be ignored. Therefore, there is no need for calculations to separate force and moment, and the detected values can be output in real time. I can do it.

When a force Fz roughly perpendicular to the forces Fx and Fy acts on the load flange 2, this force FZ is transmitted to the cruciform spacer 5 along the same path as Fx. This cross-shaped spacer 5 has a force Fx,
Since it has sufficient rigidity against Fy, it hardly bends, but its rigidity against force FZ causes it to bend weakly compared to these, so shearing strain and bending strain occur. Since the strain gauge 10 is attached to the front and rear surfaces of the vertical spacer 5a of the cross-shaped spacer, this shear strain is detected and the force Fz
is detected. Incidentally, in any direction of force, the influence of moment can be easily canceled out by the method of assembling the bridge circuit.

Next, the moment MX around the X, Y, and Z directions.

The operation of detecting My and Mz will be explained.

When the moment Mx around the force Fx acts on the load flange 2, bending strain is generated in the horizontal spacer 5b of the cross-shaped spacer ``5'' parallel to the force Fy, and the bridge circuit of the strain gauge 11 attached to the horizontal spacer 5b causes a bending strain. The moment MX is detected. In this case, the cross-shaped spacer 5 is also subjected to bending distortion due to the force Fz, but it is not detected because the bridge circuit is formed to eliminate the influence of this distortion. Leaf spring 6゜6 installed parallel to the front and rear positions
Tensile strain and compressive strain that are simpler than the moment Myt also occur in a, but the four strain gauges 8 attached to the leaf spring 6
Since the bridge circuit is formed to detect only bending strain, it is not affected by the moment MX.

When a moment My around a force Fy acts on the load flange, bending strain occurs in the vertical spacer 5a of the cross-shaped spacer 5 parallel to the force 1"x, and the spacer 5a, which is made up of four strain gauges 12, is parallel to the force 1"x. It is detected by the bridge circuit. In this case, the cross-shaped spacer 5 also causes bending distortion due to the force Fz, but it cannot be detected because the bridge circuit is formed to cancel the influence of this distortion. Simple tensile or compressive strain occurs in the leaf springs 7.7a located above and below due to MY, but a bridge circuit is formed in the four strain gauges 9 attached to the leaf spring 7 to detect only bending strain. Because it is, it is not affected by the moment My.

Furthermore, when the moment MZ around the force Fz acts on the load flange 2, torsional strain occurs in the part where the vertical spacer 5a and the horizontal spacer 5b of the cross-shaped spacer 5 are connected, and the four strain gauges 13 attached The moment MZ is detected by. Note that since the strain gauge 13 in this continuous portion is subjected to shear strain, a set of two strain gauges stacked orthogonally may be attached to the front and rear surfaces of the vertical spacer 5a. Strain gauge 1 similarly attached to vertical spacer 5a
0 can also use orthogonally stacked strain gauges.

3 to 5 are perspective views of other embodiments of the present invention, and the same parts as in the previous embodiment are designated by the same reference numerals and correspond to each other.

The embodiment shown in FIG. 3 is an embodiment in which the position at which the strain gauge is attached is changed. In this embodiment, the strain gauges 9.8 for detecting the forces Fx and Fy are attached to the same locations as in the previous embodiment, but the strain gauges 20 attached to the left and right surfaces of the vertical spacer 5a are
It serves as a stress detection element that detects z. In addition, a strain gauge 2 which is a moment detection element that detects moment MX
2 is attached at 21 places on the front and back sides of a leaf spring 6a parallel to the leaf spring 6 that detects the force Fy, and the strain gauge 21 that detects the moment My is a plate parallel to the leaf spring 7 that detects the force FX. Strain gauges 23, which are attached to the spring 7a and detect the moment MZ, are attached to the upper and lower surfaces of the horizontal spacer 5b.

In this embodiment, the forces FX and FV are detected in the same manner as in the previous embodiment, so their explanation will be omitted, but the detection of FZ, moments MX, MV and MZ will be explained below.

First, when force FZ acts on load flange 2, leaf spring 6
is transmitted to the cruciform spacer 5 and the leaf spring 7 via. Here, each leaf spring 6, 7 has sufficient rigidity with respect to the vertical spacer 5a of the cross-shaped spacer 5, and its deflection is small and can be ignored, and the vertical spacer 5a of the cross-shaped spacer 5 bends and causes bending distortion.

Therefore, the force FZ is detected by a bridge circuit of four strain gauges 20 attached to the vertical spacer 5a. In this case, the vertical spacer 5a of the cross-shaped spacer 5 is also subjected to bending strain due to the moment My around the force Fy, but the influence of the moment MV can be eliminated in forming the bridge circuit of the strain gauge, and the moment MX around the force Fx Since the strain gauge 20 is attached in a direction that does not cause sensitivity, it is not affected by the moments MX and MY.

When the moment MX around the force FX acts on the load flange 2, tensile and compressive strains are generated in the two parallel leaf springs 6.6a, but the leaf springs 7.7a and the cruciform spacer are sufficient in this direction. Due to its rigidity, deflection is small and can be ignored. On the other hand, the strain gauge 22 attached to the leaf spring 6a
Accordingly, the tensile strain is detected and the moment Mx is detected. At this time, bending strain also occurs, but this bending strain is eliminated by the bridge circuit of the strain gauge 22.

When the moment MV around the force Fy acts on the load flange 2, tensile and compressive strains occur in the leaf springs 7 and 7a, respectively, but the leaf springs 6.6a and the cruciform spacer have sufficient rigidity in this direction, so they do not bend. Small and can be ignored. on the other hand,
A strain gauge 21 attached to the leaf spring 7a detects tensile strain and compressive strain, and detects moment Mv. At this time, bending strain also occurs, but this bending strain is eliminated by the bridge circuit of the strain gauge 21. When the moment Mz around the force FZ acts on the load flange 2, the largest bending strain occurs in the horizontal spacer 5b of the cross-shaped spacer 5, so the four strain gauges 23 that are attached are
The moment MZ is detected by a bridge circuit consisting of: In this case, the strain gauges attached to each of the leaf springs 6.6a, 7.7a and the vertical spacer 5a are not affected by the moment MZ since they are all oriented in a direction that is not sensitive to the moment MZ.

In the embodiment shown in FIG. 4, the vertical spacer 5a and the horizontal spacer 5b of the cross-shaped spacer 5 are integrally formed by machining a metal block material, and because of the integral structure, the tension between the leaf spring and the spacer under load is There is no deviation at all, and detection accuracy is high under high loads. Here, each leaf spring has a structure in which it is attached to its respective spacer with a screw, so that the strain gauge can be attached accurately and easily. In this embodiment, no notch is formed in the outer spacers 3.4, and they are assembled so that a certain gap is formed between each spacer and the cross-shaped spacer 5, which is the inner spacer.

In the embodiment shown in FIG. 5, the entire first detector unit and second detector unit each consisting of a leaf spring and a spacer are integrally formed by machining from a metal block material.

Therefore, in this embodiment as well, there is no misalignment between the leaf spring and the spacer, and the detection accuracy is increased.

Note that in each of the embodiments of the present invention, one of the spacers intersecting in a criss-cross pattern is provided with a protrusion that contacts the other spacer, and a space is provided between the spacers to form a continuous portion, thereby reducing the force. The distance between the load position and the force detection position in the X direction or Y direction is shortened to reduce the influence of moment length, and the longitudinal direction of each stress detection element installed in the X direction and Y direction leaf springs is shortened. Although the positional deviation is reduced and the force detection error due to direction is reduced, in the embodiment shown in FIG. 3, the strain gauge is not attached to the protrusion, and it is not necessary to provide this protrusion. . Furthermore, in the present invention, instead of using strain gauges as stress detection elements and moment detection elements, other stress detection elements such as semiconductor gauges may be used.
II! may be deposited directly on the leaf spring.

〔Effect of the invention〕

As described above, according to the present invention, since the spacer of the detector unit formed in the donkey pal mechanism is assembled in a cross shape so as to be perpendicular to the inside of the hollow part of the other detector unit, forces in three orthogonal directions can be applied. It is possible to detect the moment around the direction, and it is also possible to detect the position of each force detection point with very small displacement in the longitudinal direction.It is also possible to output it in real time, and it is possible to detect the force according to the direction. , it is possible to detect force with small errors. In addition, forces in three orthogonal directions and their moments can also be detected, and these multidirectional forces can be detected with a very compact structure. Furthermore, since it has a compact structure, it can be attached to the wrist of an industrial robot, for example, and a processing tool such as a gripper can be attached to the load flange.

Then, when a processing tool is used to perform a fitting operation, for example, a parallel position error can be detected as a force in the pushing direction, and a tilt error can be detected as a moment, so the robot's motion can be corrected using the signal from the detector. The fitting work can be completed in a short time. Therefore, work efficiency can be improved during assembly work, etc., without increasing the positional accuracy of the workpiece or the stopping accuracy of the robot.

Furthermore, since the detector of the present invention has a small crosstalk with other forces and moments relative to the negative force, there is no need for a calculator or the like to calibrate these values □, and no processing time is required for calibration.

[Brief explanation of drawings]

1 and 2 are an exploded perspective view and an assembled perspective view of one embodiment of the multidirectional force detector of the present invention, FIG. 3 is an exploded perspective view of another embodiment, and FIGS. 4 and 5. Both are perspective views of still other embodiments. 1... Fixed flange, 2... Load flange, 3.4
...Spacer, 5...Cross-shaped spacer, 5a...
Vertical spacer, 5b...Horizontal spacer, 6.6a, 7.7
a... Leaf spring, 8.9.1o: 20-... Stress detection element, 11.12.13, 2°1, 22.23... Moment detection element.

Claims (1)

[Claims] 1. Consisting of first and second detector units of a Roberval mechanism, each of which is constructed by providing highly rigid spacers at both ends between two parallel leaf springs; One spacer of each of the second detector units passes through the hollow portion of the other detector unit and is arranged in a vertical positional relationship, and each spacer that penetrates the respective hollow portions extends through the center of the spacer. The plate springs of the first and second detector units and the spacers intersected in a cross shape are integrally configured in a cross-shaped manner at appropriate locations to detect forces in the X, Y, and Z directions. A multidirectional force detector characterized in that a stress detection element and a moment detection element for detecting moments around the X, Y, and Z directions are installed. 2. The multidirectional force detector according to claim 1, wherein the leaf springs and spacers in the first and second detector units are each formed separately and configured with screws. 3. The multidirectional force detector according to claim 2, wherein the two spacers intersecting and fixed in a cross shape are integrally formed by cutting out a metal block. 4. The multidirectional force detector according to claim 1, wherein the first and second detector units are integrally formed by cutting out a metal block material. 5. The multidirectional force detector according to any one of claims 1 to 4, wherein the spacers intersecting each other in a criss-cross pattern are integrally configured at intervals. 6. The multidirectional force detector according to claim 2 or 5, wherein one of the spacers intersecting in a criss-cross pattern is provided with a protrusion in a portion that contacts the other spacer. 7. A notch is provided in each of the inner side surfaces of the outer spacer of the first and second detector units facing the inner spacer of the other detector unit, and the other side is spaced apart from each other within these notches. A multidirectional force detector according to any one of claims 1 to 6, in which an inner spacer of the side detector unit is inserted. 8. The multidirectional force detector according to any one of claims 1 to 7, wherein a mounting flange is attached to the outer surface of each outer spacer of the first and second detector units. 9. The multidirectional force detector according to any one of claims 1 to 8, wherein the moment detection elements are all attached to crisscross spacers. 10. A patent claim in which a moment detection element for detecting moments in the X and Y directions is attached to a leaf spring, and a moment detection element for detecting moments in the Z direction is attached to spacers crossed in a cross shape. A multidirectional force detector according to any one of ranges 1 to 8. 11. The multidirectional force detector according to any one of claims 1 to 10, wherein the stress detection element and the moment detection element are strain gauges.