JPS6042629A - Multicomponent force and moment measuring body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] This invention relates to a measuring body for measuring multidimensional forces and multidimensional moments using resistance wire strain gauges.

[Prior art and its problems]

Measuring bodies of this type are known, for example, from German Patent Publication No. 252,979.
6, No. 2727704 and periodical magazine "Electro-X" Vol. 17, No. 27, December 1982, No. 1
It is known from the article "Tactile sense for industrial robots" on page 1.

However, in these known measurement bodies, the force and moment acting in each direction of three-dimensional coordinates are analyzed using a large number of sensors with direction selectivity. This requires an extremely expensive structure, and the cost of the strain gauge is also high.

[Purpose of the invention]

An object of the present invention is to provide a measuring body that is small in size and has low manufacturing cost.

[Key points of the invention]

In this invention, a strain gauge is mounted on a measurement body that is integrated with a receptor that receives longitudinal and lateral forces and moments at a predetermined position, and the strain gauges are mounted on a measurement body that receives the forces and moments by means of a pair of half-circuits and di-circuits. (5) Set the direction at a predetermined position with respect to the stress direction within the measuring body so that a uniquely measured sensitivity can be obtained, and calculate the force and moment from the detected values of the half-branch and di-circuit. This is achieved by attaching a sufficient number of strain gauges to obtain a sufficient number of equations, and constructing a measuring body by connecting one end of each strain gauge in parallel and separating the other end so that it can be accessed.

In this invention, the force acting on the measuring body is resolved into three-dimensional hexaaxial components by a strain gauge with component-selective sensitivity mounted on one integrated measuring spring body. However, it is unavoidable that components in other directions will be mixed into each strain gauge, so simply selecting the placement and orientation of the strain gauges on the integrated measurement spring body described above will yield insufficient results. I can't get it. Therefore, the present invention aims to achieve the same effect by using an electronic method which is cheaper than improving the precision of force component decomposition by using the mechanical structure of the measuring body.

In accordance with the above objectives, it is expedient to construct the measuring body as a (6) hollow cylinder which is fixed at one end. Then, the free end of the cylinder is covered with a force receiving cup and rigidly fixed. The length of the force receiving cup that covers the edge of the hollow cylinder at about one-third of the center of the effective length of the hollow cylinder is defined as I-1.This position is defined as the force receiving surface in the lateral direction. At least seven strain gauges are set in the force receiving part on the circumference line of the hollow cylinder corresponding to the cut where the force receiving interface and at least another cut plane parallel thereto intersect with the cylinder surface, respectively, with reference to the XY coordinate axes. Determine the position and orientation as shown below and attach. Two of each are arranged so as to form radially opposed pairs in the direction of the cylinder axis and a direction perpendicular thereto, and at least two of them are arranged so as to be inclined in directions different from each other by 45 degrees with respect to the direction of the cylinder axis. When the strain gauge is installed as described above, three forces that are spatially orthogonal to each other are generated.
Three components, component and moment, can be measured. Further, if only a smaller number of components are to be constant, the number of strain gauges may be smaller than the above.

In an embodiment of the invention, the first
Two strain gauges are arranged on the peripheral line of the strain gauge in a radially opposed pair in the direction of the peripheral line.

At the same azimuth angle, two strain gauges are oriented in the axial direction, and a pair of υ strain gauges are oriented in the axial direction of the cylinder.
° It is placed on another circumferential #& line at a certain distance from the circumferential line of ml, tilted in different directions from each other. 1 on yet another peripheral edge on the opposite side of the first peripheral line.
A pair of strain gauges is tilted in the same direction as the cylinder axis by 45 degrees and placed at the same azimuth as the first tilted pair.
do.

In a different embodiment of the present invention, two strain gauges are arranged in pairs facing each other in the radial direction on the peripheral line determined by the force-receiving surface and facing the peripheral line. Also, on the same peripheral line, at a position 90' azimuth away from the above two strain gauges, there is one strain gauge oriented in the axial direction, and two strain gauges in the axial direction and 4
They are arranged so as to be tilted in different directions by 5° and overlapped with each other. and 90 on another different peripheral line.
'%1111 in the axial direction and in the circumferential direction with the azimuths shifted from each other! I strain gauges are attached to each.

In accordance with the purpose of this invention, a set of 'r
It is expedient to construct a series circuit of a strain gauge and a fixed resistor, each of which can be connected in parallel between the two terminals of the t-source.

Then, connect points between each strain gauge and fixed resistor to the outside.

- In a circuit configuration different from the above, the fixed resistor is replaced by a power supply group with one end connected in parallel. The parallel connected ends of the power supply group are directly connected to the parallel connected ends of the strain gauge group.

It is advantageous to further modify the strain gauge circuit configuration described above to consolidate the °C power supply group into two sets of power supplies whose ends are connected in parallel, and to make it possible to connect each power supply to two strain gauges via a switch mechanism. .

With this circuit configuration, it is possible to measure the two selected strain gauges twice by switching the power supply, and as a result, a complementary effect can be obtained that averages out errors caused by variations in contact resistance. .

[Embodiments of the invention]

(9) Next, the present invention will be explained in more detail with reference to figures of embodiments.

In Figure 1, three-dimensional force components P1* are spatially orthogonal to each other.
P2+P3 and the moment components M,,M,,M,are shown. In addition, each moment component is as shown by the arrow in the figure.
Of course, it is also possible to measure forces in directions different from the above components using a known measuring body or a measuring body according to the present invention, but in that case, the force will be the same as above. It is decomposed into components in each dimension direction.

The forces and moments shown in Figure 1 are shown in Figure 28 or gg.
As shown in Figure d, it acts to distort the cylindrical measuring object. The tiE2a diagram shows a pattern in which the cylinder Z becomes convergent and thicker due to the pressure P1 acting in its axial direction.

Figure 2b shows a state in which the cylinder Z is distorted into an S-shape due to the force receiving force P3 from the lateral direction acting on the outer edge of the force receiving cup. In this case, the outer edge of the force receiving cup is A force receiving surface is determined, which in this illustration is located at the center of the cylinder. Also, in Fig. 2c, torque M2 acts on cylinder (10) cylinder Z, and this torque acts on cylinder Z.
shows a state in which the force acts as a pure bending force. FIG. 2d shows a state in which torque M+ is applied around the longitudinal axis of the cylinder Z to generate torsional stress in the cylinder.

Figure 3a shows the cylinder Z and the three force components P1 to P.
3 is shown. The force receiving force, the peripheral line corresponding to the cut made by the outer edge surface of the cylinder intersects with the cylinder surface is B, and the parallel lines drawn at equal intervals on both sides of the peripheral line B are A.
and C. Figure 3b shows these lines B, A and C.
This shows the arrangement of eight resistance wire strain gauges 1 to 8 arranged above, and the positional relationships on the cylinder surface on these three lines are shown at azimuth angles of 0°, 90°, 180° and 270°, respectively. has been done.

FIG. 3C shows once again the three-dimensional force components P1 to P3 and the moment components M to M3. And each of these components P1. P2. P3 as well as Ml.

The normalized values of strain that M, , and M give to the resistance wire strain gauge are listed in the following table in the form of a matrix.

The above table shows the azimuth angle of the cylinder surface indicating the position on each circumferential line of each strain Gougier to 8, and the angle indicating the orientation of each gauge as an inclination with respect to the cylinder axis.

From these matrices and matrix tables, it is possible to determine which strain gauges are configured between two strain gauges, and whose output values include only the force and moment components weighted by a limited number of the above matrices and matrix tables. You can find half-bridge circuits. Such an expansion formula is shown in the table below.

If as many bridge circuit output end values as shown in the above table are obtained, a sufficient number of equations will be established to calculate individual components in each coordinate axis direction. The calculation formula obtained from the above table is shown below.

-3,33・Ca+Cs2+2M, -2P2-2M3P
2=06・(-3,33) +08 c, +c, :+pm ps-M.

Ml = -C5-04 M2: C7 M3-C6・(-1,66) Cr'C+=-1,3Pt-P2+0.7Ma 1.3
P1+P2-0.7M3=-2,6P1p, =c2・
(-0,385)-CtΦ(-0,385)Ps''C5 FIG. 4 shows a different embodiment of the present invention, in which seven strain gauges are pasted on peripheral lines B and C on cylinder Z. The arrangement state is shown.Although a peripheral line A is also drawn in this figure, strain gauges are not mounted on this line in this example.As in the previous example, each gauge is given a serial number from 1 to 7, and each gauge is The following table lists the strain matrices and rice cakes.

From the table above, the equation holds true as in the previous example, and the following solution is obtained. The term in parentheses on the left side of each equation is the number of strain gauge combinations (14) that make up each half-pre, di-circuit.

(4-5) = 2Mt (1-3) = 0.6M3 (1-6) - (1-3) = 0.3P2 (4-3) -
(1-2)+(2-4)=2.5P1(1-2)-(
4-3) -2I'+-M1=1.5M2(2-7)+
2M2 Knee P3 #1fJ5 Connect one end of each strain Gougier to 8 in parallel, and connect fixed resistors R1 to R to the other end, respectively.
8 are connected in series, and in order to configure a bridge circuit, serial numbers 1 to 8 are attached to each connection point between the l gauge and the fixed resistor, and the wires are connected externally.
This shows a wiring diagram that allows the voltage to be measured with a voltmeter.

Measurements, calculations and evaluation of results can be carried out using properly programmed microprocessors.

In the circuit shown in FIG. 5, a similar circuit can be constructed even if each of the fixed resistors R1 to R8 is replaced with a constant current power supply. In that case, the power supply Us shown in the figure becomes unnecessary, so one end of each constant current power supply is connected in parallel with each other and directly connected to one end of each strain gauge that is connected in parallel with each other.

FIG. 6 shows an embodiment in which the above circuit configuration is further modified. Here, the individual constant current power supplies described above are connected to two sets of power supplies Q1. Q2, and the other free end of each power source is brought into contact with any pair of free ends of each strain Gougier to 8, respectively. In order to average the contact resistance and contact voltage when switching the contacts, it is also possible to measure each pair of strain gauges twice by switching the constant current power supply as shown by the broken line in the figure. be.

〔Effect of the invention〕

In this invention, strain gauges are mounted on a measurement body having a relatively simple structure with their positions and orientations appropriately determined, and these strain gauges are combined in pairs to generate half-circuit and dicircuit forces.
Since the large number of measured values obtained from the 3-dimensional method is appropriately electronically processed to eliminate different components contained in each measured value, only the three-dimensional components of force and moment are resolved and measured. Therefore, compared to the method of obtaining the above effect through the mechanical configuration of the measuring body, a measuring body that is cheaper and more compact can be provided.

[Brief explanation of drawings]

Figure 1 is a diagram illustrating each component of force and moment in each three-dimensional coordinate axis direction, and Figures 28 to 2d illustrate states in which each of the above components acts on a cylindrical measuring body and distorts it. FIG. Figures 3m to 3C are views showing the vertical cross section and the arrangement and orientation of the strain gauges of the embodiment of the measuring body according to the present invention, and Figure 4 is a view showing the arrangement and orientation of the strain gauges in a different embodiment. FIGS. 5 and 6 are connection diagrams respectively showing two different embodiments of the circuit configuration of the strain gauge. A, B, C peripheral line of the cylinder surface, K: force receiving force, Z: measuring body cylinder, 1 to 8: resistance wire strain gauge,
R, -R,: fixed resistance, Qt, Q2: power supply. (17)

Claims (1)

[Claims] 1) A measuring body for measuring multi-component forces and moments using strain gauges, which is integrated with a receptor that receives longitudinal and lateral forces and moments at predetermined positions. The strain gauge is oriented at a predetermined position with respect to the stress direction inside the measuring body so that the sensitivity that allows the force and moment to be uniquely measured is obtained by a half-bridge circuit that pairs the gauges on the measuring body. A sufficient number of equations can be obtained to calculate the force and moment from the detected values of the half-bridge circuit. A multi-component force and moment measurement body characterized by: 2. The measuring body according to claim 1, wherein the measuring body is a hollow body rigidly connected to a force-receiving cup having one end fixed and the other end placed over it for the purpose of measuring three component forces and three moments. a cylinder, the rim of the core cup defining a lateral force receiving surface located approximately one-third of the effective length of the hollow cylinder toward the center, and each force receiving surface and at least one other cutting surface parallel thereto; and at least seven strain gauges on the peripheral edge of the hollow cylinder corresponding to the cut formed on the cylinder surface, two pairs of which are radially opposed pairs on the cylinder axis and in a direction perpendicular thereto, and at least The other two are multi-component force and moment measuring bodies, characterized in that they are mounted tilted in different directions by 45 degrees with respect to the cylinder axis direction. 3) In the measuring body according to claim 2, on the first peripheral line determined by each force receiving surface, there are two axially extending lines at the same azimuthal angle as the two strain gauges (317).
strain gauges (4, 8), and a pair of strain gauges (2°6) which are 90' azimuth shifted from them and tilted in directions different from each other by 45° with respect to the axial direction. On the other peripheral line located on the opposite side of the peripheral line, there is another pair of strain gauges (l. 5) tilted in the same direction as the axial direction by 45°; and a pair of tilted strain gauges (2, 6). A multi-component force and moment measuring body characterized in that the body is mounted at the same azimuth angle as the body. 4) In the measuring body according to claim 2, two strain gauges (1*a) are mounted on the peripheral line determined by the force receiving part in a radially opposed pair in the direction of the peripheral line. In addition, on the peripheral line, there is one strain gauge (2) oriented in the axial direction with an azimuth angle of 90° shifted from these, and two strain gauges (4, 4, 5) are mounted, and one strain gauge (7 and 6) is mounted on another different peripheral line, shifted by 900 azimuth angle from each other, in the axial direction and in the direction of the peripheral line.
A multi-component force and moment measuring body characterized in that each of the following is attached. 5) In the measuring body according to any one of claims 1 to 4, each strain gauge is fixed to one strain gauge by the same number of high resistors whose one ends are connected in parallel to each other. 1. A multi-component force and moment measuring device comprising a resistor, the interconnection of which is brought out to the outside, and combined into a series circuit connectable in parallel between a pair of power supply terminals. 6) In the measuring body described in claim 5, the fixed resistor is replaced by a power supply group whose ends are connected in parallel to each other, and the mutually connected ends of the power supply group are connected to each other of the strain gauge groups. Multi-component force and moment measuring body with 1% sign connected to parallel connected ends. 7) A multi-component measuring body according to claim 6, characterized in that instead of a large number of power supply groups, power supplies are provided whose ends are connected in parallel to each other and which are capable of switching two strain gauges at a time. Force and moment measuring body.