SU1332144A1 - Strain measuring device - Google Patents

Abstract

The invention relates to a measurement technique and can be used in measuring strain. The aim of the invention is to increase the accuracy due to the correction of the conversion coefficient of the amplifier 3 by periodically supplying the reference voltage directly to its input. In the calibration mode, the reference voltage from the capacitor 8 through the voltage divider of resistors 9, 10 is applied to the input of the amplifier 3 in series with the output voltage of the strain gauge G. 1 Il. (Ls

Description

five

ten

15

20

25

11332144

This invention relates to a measurement technique and can be used in measuring strain.

The aim of the invention is to improve the accuracy by correcting the conversion coefficient.

The drawing shows the block diagram of the strain gauge transducer.

The strain gauge transducer contains a strain gauge 1, a power source 2 included in the power diagonal of the strain gauge 1, an amplifier 3 (for example, differential) included in the measuring diagonal of the strain gauge 1, serially connected first 4 and second 5 keys, sequentially connected third 6 and fourth 7 keys, a capacitor 8 and a voltage divider of two resistors 9 and 10, the first resistor 10 is included in the input circuit of the amplifier 3, the first contact of the first switch 4 is connected to the first output of the power supply 2, the first contact of the third to Ichu 6 is connected to the second output of the power source 2, which is connected to the common bus of the converter, the first capacitor plate 8 is connected to the second contact of the first switch 4, the second capacitor plate is connected to the second contact of the third switch 6, the second contact of the second switch 5 is connected to the first output of the second resistor 9, the second output of the second resistor 9 is connected to the first output of the first resistor 10, and the second contact of the fourth switch 7 is connected to the second output of the first resistor 10.

t Strain transducer works as follows.

In the operating mode, the output voltage of the strain gauge I, proportional to the relative change in the resistance JR / R of the strain gauges of the strain gauge 1 and the voltage of the power supply 2, is fed to the input of the amplifier 3. The keys 4 and 6 are open and the keys 5 and 7 are open. Consequently, the charging coagulator 8 is charged before the voltage of the power supply 2 and the input of the amplifier 3 is not affected by any additional signals. The output voltage of the converter is

thirty

35

40 and

45 p

50

and.

11 UH RK ,,

(one)

UH is the voltage source of the tani;

2 pi

K is the gain of the amplifier 3.

iB calibration mode opens the keys .4 and 6, the keys 5 and 7 are closed. The exemplary voltage U from the capacitor 8 is applied to the voltage divider of resistors 9 and 10. The voltage available on the resistor, 10, is applied to the input of amplifier 3 in series with the output voltage of the strain gauge 1, the output voltage of the converter

4R „. „Р-10

and

. + and.

-to,

(2)

fO -9

From the results of two measurements, you can determine / JR / R as follows:

, p / t) UjRj2

ak / c. - ,, T1 gr 1J.TJ / t5.

U2-lb XV 3

(3)

R, / Rg

From formula (3) it follows that the total error is determined by the error of resistors 9 and 10 and is

4 VTd R

(four)

if the relative error values of resistors 9 and 10 are equal and uncorrelated. The measurement accuracy is increased by 3 / Y, i.e. more than 2 times.

Claims (1)

Formula Investigation 35 A strain gauge transducer containing a strain gauge, a power source included in the power diagonal of the strain gauge, an amplifier included in the measuring diagonal of the strain gauge, 40 and the first switch, which is different from the fact that, in order to increase the accuracy due to the correction of the conversion coefficient, it is equipped with three switches, a capacitor and a divider on 45 strands of two resistors, the first resistor of the voltage divider is included in the input circuit of the amplifier, the first the key is connected in series with the second key, the third key is sequentially connected to the fourth key, the first contact of the first key is connected to the first output of the power source, the first contact of the third key is connected to the second, output of the source 55 power supply, the first capacitor plate is connected to the second contact of the first key, the second capacitor plate is connected to the second contact of the third key, the second contact is I33214A The second key is connected to the first output of the voltage divider, and the second contact of the second resistor of the voltage divider of the fourth KP is connected to the second, the second output of which is connected to the output of the first resistor of the divider with the first output of the first voltage resistor.