JPS58225331A - Apparatus for measuring multi-component force - Google Patents

Abstract

PURPOSE:To calculate moment in good preciseness, by simple constitution wherein a measuring center M, C is provided in the vicinity of the leading end of a strut while a moment center is provided to the other end thereof and the distance therebetween is set to L. CONSTITUTION:Force shown by a write arrow F and moment shown by an arrow M are simultaneously acted on the measuring center M, C in the vicinity of the leading end of a strut 21. When force F and moment M' are acted on the moment center 24 of a detector at this time, the relation of formiula M'= M+FXL(distance) is formed between the moments M, M'. When this detector detects F and M' and if it is a two-component force detector, the moment M is calculated from formula M=M'-FXL. By properly selecting amplification ratios AF1, AF2, AM1, AM2 of each amplifiers 31, 32, 36, 37 and the coefficient K of a coefficient setting device 41, M2=M is taken out as output when M1 is M'. In this case, the output of the coefficient setting device 41 is added to an adder 38.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-force measuring device capable of measuring four component forces in each direction of force and moment acting on a certain point on an object.

When testing various materials or equipment, there is a need to accurately determine the force and moment acting on a certain point. In order to accurately measure forces and moments that act in any direction, it is common to measure them as component forces in each direction. In an orthogonal linear coordinate system as shown in Figure 1, the force and moment acting on a point on an object are represented by three types of forces Fx, Fy, Fz and three types of moments Mx, My, Mz, respectively. These are usually called six component forces, and by combining them, forces and moments in all directions can be expressed. .

In order to release such six component forces, it is customary to insert a sensor called a multi-force detector between the object to be tested and the fixed side, and extract the various component forces acting on the sensor.

For example, when a model aircraft is placed in a wind barrel and various component forces acting on the body of the aircraft in the air are measured, an arrangement as shown in FIG. 2 is used.

In FIG. 2, an aircraft model 2 placed inside a wind cylinder 1 is connected via a strut 3 to a multi-force detector 4 located outside the wind cylinder. A multi-force detector 4 is attached to the fixed end 5. The purpose of this test is to detect multiple forces acting on the measurement centers M and C of the aircraft model 2.

If the detector 4 is inside the model, its moment center is set as the measurement center M, C so that it is suitable for measurement.

However, in general, due to dimensional constraints and operational convenience, the detector 4 is installed outside the model as shown in Figure 2. There are many. In this case, it is often difficult to align the output of the detector with the measurement center of the model. The reason is as follows.

FIG. 3a shows an example of a moment detector in which strain gauges A, B, C, and D are attached to the moment detection beam 6. The lower end of the detection beam 6 has a flange 7 for fixing to the fixed end 5. Detection beam 601
Strain gauges A and B are on surface 8.

On the other side 9, strain gauges C and D are respectively pasted as shown in Figure 3.1, the point 11 where the force as indicated by the arrow F acts, and the center 1o of the strain gauges A, B, C, and D. When the distance between the strain gauges A, B, C, and D is connected as shown in FIG. 3C, the output e of the bridge circuit is expressed as follows.

e button FXLφ... (1) It is well known that FXL with e button is a moment generated at the center 1o of the strain gauge. In this way, it is easy to determine the moment acting on a predetermined point inside the detector.

However, when the measurement centers M and C are outside the detector as in the example shown in FIG. 2, the above process cannot be performed and special consideration is required. For example, a pyramid-type multi-force detector is known for determining the moment when the center of the open side is outside the detector, but this detector is complicated and expensive. Furthermore, since it is necessary to correctly align the measurement center with the center of the pyramid of the detector, there are problems with maintenance and operability is reduced.

An object of the present invention is to eliminate the drawbacks of these conventionally known devices and provide a multi-force measuring device that is inexpensive, highly accurate, and has excellent operability.

According to the present invention, a simple and inexpensive device is used. Figure 4 is a block diagram for explaining the basic operation of the multi-force measuring device according to the present invention. , this detector 22 is attached to a fixed end 23. It is assumed that measurement centers M, C, dust, and a moment center 24 of the detector 22 are located near the tip of the strut 21, and the distance between them is set. In such a configuration, when the force of the white arrow F and the moment of the arrow M are acting simultaneously on the measurement centers M, C, it is assumed that the force F and the moment M' are acting on the moment center 24 of the detector. Then, there is a relationship between each moment M and M' as shown in the following equation.

. M' = M + FXL (2) Assuming that this detector 22 is a two-component force detector that detects F and M', to obtain the moment M from the output of this detector, (2 ) is modified from the following equation.

M=M'-FXL@・・・(2') Equation (2') is obtained from the block diagram in FIG.

In FIG. 5, the output F from the detector is supplied to an input 33 of a circuit to which two amplifiers 31 and 32, whose amplification factors are A and AF2, respectively, are connected. In this case, an output F is obtained at the output 35 of the amplifier 32. The lower circuit has amplification factors of A and AM2, respectively.
Two amplifiers 36 and 371 are connected via an adder 38, whose input 39 is supplied with the detector output M. A coefficient setter 41 is connected to the line 34 of the upper circuit in a branched manner, and an output 42 multiplied by a predetermined coefficient is obtained. This output 42 and the output 40 of the amplifier 36 of the lower circuit are applied to two outputs of an adder 38, and a summed output 42 is obtained.

This summation output 42 passes through an amplifier 37 and produces an output M2 at an output 43. It is assumed here that the coefficients of the field coefficient adder 41 also include plus and minus signs.

In the example of Fig. 5, the amplification factor AFl 'AF2 of each amplifier is
．． AM4. By appropriately selecting AM2 and the coefficient K of the coefficient setter, it is possible to take out M2=M as an output when M□ is M'.

Furthermore, after setting the coefficient K of the coefficient setter to correspond to the distance using a dial or digital switch, etc., the amplification factor AFil AF21AM1. AM2
Since it is possible to adjust the , the following characteristics can be obtained.

That is, when the above-described adjustment is completed, the value of the coefficient indicates the distance from the moment center of the detector to the measurement center of the model. Therefore, by changing this coefficient, the measurement centers M and C of the model can be changed appropriately according to the value of the coefficient.

Such adjustment can also be practically performed by the method described below.

1) AFl, AF2. Set AMl and AM2 arbitrarily.

ii) Set K to be the distance between the position of the trial force F and the moment center of the detector.

) Apply force F.

iv) In this state, adjust AF2 and set the output F to a predetermined level.

v) Adjust AMl and set the output M2 to zero.

vi) Add a pure moment M so that the output at that time becomes a predetermined magnitude.

vii) If operations iv) to vi) are impossible, readjust AF, , A, and Ml and repeat operations 1ii) and subsequent steps.

FIG. 6 shows a block diagram of the system shown in FIG. 2 in which the detector 4 is a six-component force detector having an internal moment center. In this example, the measurement center of the model is shifted only in the Z direction from the moment center of the detector. The symbols in the figure represent the same meanings as in Figure 5, except for the subscripts x,
The 6-component force is indicated by y and z, and the type of coefficient is indicated by 1.2.

Now, even if the distance between the measurement center of FX and the moment center of My' and the distance L2 between the measurement center of Fy and the moment center of MX' are Ll to L2, set 1 to the coefficient as T, Corresponds to 1 and also 2
By associating L2 with L2, the moments at the four centers of the model can be measured independently. Therefore, the moment center of the detector is Mx', My1MZ
'There is no need to match one point for each.

Furthermore, it goes without saying that the above-mentioned contents can also be applied to directions other than the Z direction, for example, the X and Y directions, and to cases where these directions are appropriately combined.

Furthermore, this device is not limited to 6-component force measurement, but can be applied to any detector that combines force and a moment that is added by the force to the measured value. . .

[Brief explanation of the drawing]

Figure 1 shows the 6-component force in rectangular linear coordinates. FIG. 2 shows the basic configuration for measuring component forces on an aircraft model inside the wind body. Figures 3a and 3b show the arrangement of the detection beam and strain gauges. Figure C shows a wiring diagram of the strain gauge. FIG. 4 shows the basic configuration of the component force detector according to the present invention. FIGS. 5 and 6 are block diagrams of basic circuits that perform analog calculations on component force detection outputs. A γli'i' on page t'71 (no change in content) Fig. 1 A Fig. 2 Fig. 3 (a) (b) (c) Fig. 4
Figure 5 Figure 6 Procedural amendment 11. picture. Showa da'/''/θ month 2611 Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office ■, Indication of the case Showa 9'7 Patent Application No. 1owoL/-279 No. 2,
Name of the invention 79 or power,'' Lu 11 Biwa Te 3, Person making the amendment Relationship to the case Applicant 4, Attorney I 1 Location: 8-1 Toranomon 2-chome, Minato-ku, Tokyo (+j? 1°)゛Country/I) [Telephone 03 (502) 1476
(Yo'J Koguchi 5, date of amendment order February 7, 1972)
6. Subject of amendment 1 -°゛ Power of attorney Pa≠Shunne Portrait ÷ Engraving of the drawings. (No change in content) 7. Contents of amendment

Claims (1)

[Claims] (1) The output of a component force detector that combines a predetermined number of strain gauges is corrected, and when the measurement center is deviated from the moment center of the detector, the component force at the measurement center is 8] In the multiforce measuring device used to obtain the measured values, the measured value (M') obtained at the moment center of the detector, 4
From the force measurement value (F) obtained at the measuring center and the distance (L) between the moment center of the detector (24) and the four measuring centers (M, C,), M = M' - FXL. A multi-force measuring device characterized by having a built-in mechanism for calculating a moment value (M) at a measurement center. (2. The multi-force measuring device according to claim 1, wherein the calculation mechanism includes a mechanism that can set the distance between the detector moment center and the measurement center as a variable value. (3) In the multi-force measuring device according to claim 1, the calculating mechanism includes a multi-force measuring device that calculates the multi-force force at the measurement center even when the moment center of the detector is at a different position for each component force. The above device has a built-in correction mechanism that can measure force.