CN217384131U - Strain measuring circuit capable of eliminating influence of long wire - Google Patents
Strain measuring circuit capable of eliminating influence of long wire Download PDFInfo
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- CN217384131U CN217384131U CN202221334595.0U CN202221334595U CN217384131U CN 217384131 U CN217384131 U CN 217384131U CN 202221334595 U CN202221334595 U CN 202221334595U CN 217384131 U CN217384131 U CN 217384131U
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Abstract
The utility model discloses a can eliminate strain measurement circuit of long wire influence in the field of strain measurement, including first constant current circuit and second constant current circuit, the output current of first constant current circuit and second constant current circuit is equal, and the output of first constant current circuit and second constant current circuit links to each other with two inputs of offsetting amplifier circuit respectively, and two inputs of offsetting amplifier circuit link to each other with the both ends of being surveyed foil gage R, and amplifier circuit's output links to each other with the ADC circuit, and the ADC circuit links to each other with microprocessor MCU; first constant current circuit and second constant current circuit's output current is i1 and i 2 respectively to i 1= i 2, two the same constant current circuit, the signal is through offsetting the test result that obtains behind the amplifier circuit, can offset the wire resistance who is connected with the foil gage R that is surveyed to measurement accuracy's influence, so the utility model discloses can measure with the strain capacity.
Description
Technical Field
The utility model relates to a strain measurement circuit in the field of strain measurement control.
Background
The strain is the phenomenon that an object deforms under the action of external pressure or tensile force, the strain gauge is mainly a measuring element for sensing force, the strain gauge is attached to a test main body, the deformation of the test main body caused by the application of force is utilized, then the resistance change proportional to the application of force is obtained, and the magnitude of the applied force can be indirectly measured. By measuring the force, many other physical quantities can be measured. The conventional method of measuring strain is to convert this proportional relationship of resistance to voltage via a wheatstone bridge. In many practical applications, a certain distance exists between a measured component and a tester, and at this time, the component needs to be connected through a long lead, the resistance of the lead becomes a part of the bridge arm resistance, and the longer the lead is, the larger the resistance of the lead is, the larger the resistance value corresponding to the measured strain gauge obtained through measurement is, and the measurement accuracy is affected.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a can eliminate strain measurement circuit of long wire influence, the design is more retrencied, measures more accurately.
In order to realize the above object, the utility model provides a can eliminate strain measurement circuit of long wire influence, including first constant current circuit and second constant current circuit, first constant current circuit and second constant current circuit's output current is equal, and first constant current circuit and second constant current circuit's output links to each other with two inputs of offsetting amplifier circuit respectively, and two inputs of offsetting amplifier circuit link to each other with the both ends of being surveyed foil gage R, and amplifier circuit's output links to each other with the ADC circuit, and the ADC circuit links to each other with microprocessor MCU.
Compared with the prior art, the beneficial effects of the utility model reside in that, first constant current circuit and second constant current circuit's output current is i1 and i 2 respectively to i 1= i 2, among two the same constant current circuits, the test result that the signal obtained after offsetting amplifier circuit can offset and be surveyed the influence of wire resistance that foil gage R is connected to measurement accuracy, like this the utility model discloses can meet an emergency and measure.
As a further improvement of the utility model, the first constant current circuit comprises a reference power supply chip U1 and a reference power supply chip U1V IN The end is connected with the positive pole of the direct current power supply, the negative pole of the direct current power supply is grounded, and the voltage of the reference power supply chip U1 is V OUT Terminal andone end of the current-limiting resistor R1 is connected, and the other end of the current-limiting resistor R1 is respectively connected with the GND end of the direct-current power supply and one input end of the amplifying circuit; the second constant current circuit comprises a reference power supply chip U2 and a reference power supply chip U2V IN The end is connected with the positive pole of the direct current power supply, the negative pole of the direct current power supply is grounded, and the voltage of the reference power supply chip U2 is V OUT The end of the current limiting resistor R2 is connected with one end of a current limiting resistor R2, and the other end of the current limiting resistor R2 is connected with the GND end of the direct current power supply and the other input end of the amplifying circuit respectively.
Therefore, the first constant current circuit and the second constant current circuit share one direct current power supply, and the output current is respectively reduced through the current limiting resistor R1 and the current limiting resistor R2, so that the current is not too high, the latter circuit is not burnt out, and the measurement precision can be ensured.
As a further improvement of the utility model, amplifier circuit includes instrumentation amplifier A1, instrumentation amplifier A1's the in-phase input end links to each other with current-limiting resistance R1's the other end, instrumentation amplifier A1's inverting input end links to each other with current-limiting resistance R2's the other end, the one end of being surveyed foil gage R links to each other with current-limiting resistance R1's the other end through long wire 1, the other end of being surveyed foil gage R links to each other with current-limiting resistance R2's the other end through long wire 2, the other end of being surveyed foil gage R still is through long wire 3 ground connection, instrumentation amplifier A1's output links to each other with the ADC circuit, long wire 1, long wire 2 is the same with long wire 3's resistance value.
Thus, R1, R2 and R3 are respectively equivalent to the wire resistances of the long wire 1, the long wire 2 and the long wire 3, R1= R2= R3, the voltage U + of the non-inverting input terminal of the instrumentation amplifier to the reference ground is the sum of the voltage generated by the current i1 flowing through R1 and R and the voltage generated by the current i 1+ i 2 flowing through R3, the voltage U-of the inverting input terminal of the instrumentation amplifier to the reference ground is the sum of the voltage generated by the current i1 flowing through R2 and the voltage generated by the current i 1+ i 2 flowing through R3, the gain is 1 because of the absence of the design of the instrumentation amplifier, the output voltage is U + minus U-, and the final result is found to be R multiplied by i1 through calculation, and the voltages generated by the resistances of the long wires are mutually cancelled by positive and negative phases.
As a further improvement of the present invention, the resistance values of the long wire 1, the long wire 2 and the long wire 3 are not more than 20 Ω; therefore, the resistance values of the three long wires are limited within 20 omega, and the influence of overlarge resistance values on a measurement result is avoided.
As a further improvement of the present invention, the output currents of the first constant current circuit and the second constant current circuit are not more than 10 mA; therefore, the currents of i1 and i 2 are limited within 10mA, so that the circuit is safer as a whole, and the measurement accuracy is guaranteed.
Drawings
Fig. 1 is a first constant current circuit diagram of the present invention.
Fig. 2 is a second constant current circuit diagram of the present invention.
Fig. 3 is a circuit diagram of the offset amplifier of the present invention.
Detailed Description
The present invention will be further explained with reference to the accompanying drawings:
the strain measurement circuit capable of eliminating the influence of the long lead comprises a first constant current circuit and a second constant current circuit, wherein the output currents of the first constant current circuit and the second constant current circuit are equal, the output ends of the first constant current circuit and the second constant current circuit are respectively connected with two input ends of a counteracting amplification circuit, the two input ends of the counteracting amplification circuit are connected with two ends of a measured strain gauge R, the output of the amplification circuit is connected with an ADC (analog to digital converter) circuit, and the ADC circuit is connected with a microprocessor MCU (micro controller unit).
The first constant current circuit comprises a reference power supply chip U1 and a reference power supply chip U1V IN The end is connected with the positive pole of the direct current power supply, the negative pole of the direct current power supply is grounded, and the voltage of the reference power supply chip U1 is V OUT The end of the current limiting resistor R1 is connected with one end of a current limiting resistor R1, and the other end of the current limiting resistor R1 is connected with the GND end of the direct-current power supply and one input end of the amplifying circuit respectively; the second constant current circuit comprises a reference power supply chip U2 and a reference power supply chip U2V IN The end is connected with the positive pole of the direct current power supply, the negative pole of the direct current power supply is grounded, and the voltage of the reference power supply chip U2 is V OUT The end of the current limiting resistor R2 is connected with one end of a current limiting resistor R2, and the other end of the current limiting resistor R2 is respectively connected with the GND end of the DC power supply and the other input end of the amplifying circuit。
The amplifying circuit comprises an instrument amplifier A1, the non-inverting input end of the instrument amplifier A1 is connected with the other end of a current-limiting resistor R1, the inverting input end of the instrument amplifier A1 is connected with the other end of a current-limiting resistor R2, one end of a tested strain gage R is connected with the other end of a current-limiting resistor R1 through a long lead 1, the other end of the tested strain gage R is connected with the other end of a current-limiting resistor R2 through a long lead 2, the other end of the tested strain gage R is grounded through a long lead 3, the output end of the instrument amplifier A1 is connected with the ADC circuit, and the resistance values of the long lead 1, the long lead 2 and the long lead 3 are the same.
The resistance values of the long wire 1, the long wire 2 and the long wire 3 are not more than 20 Ω; the output current of the first constant current circuit and the second constant current circuit is not more than 10 mA.
The utility model discloses in, including reference power supply chip U1 and reference power supply chip U2, connect a DC power supply jointly, produce the same reference voltage, two way reference voltage are respectively through concatenating current-limiting resistance R1R 2, produce two sets of invariable electric currents i1 and i1, and i 1= i 2.
One end of the strain gauge R to be tested is connected with a constant current i1 in series through a long lead 1 and is connected to the non-inverting input end of an instrumentation amplifier A1, the other end of the strain gauge R to be tested is connected with another constant current i 2 in series through a long lead 2 and is connected to the inverting input end of the instrumentation amplifier, and the other end of the strain gauge to be tested is connected to the reference ground in the circuit through a long lead 3. The wire resistances of the three long wires are equivalent to R1, R2, R3, R1= R2= R3, the voltage U + of the non-inverting input terminal of the instrumentation amplifier to the reference ground is the sum of the voltage generated by the current i1 flowing through R1 and R and the voltage generated by the current i 1+ i 2 flowing through R3, the voltage U-of the inverting input terminal of the instrumentation amplifier to the reference ground is the sum of the voltage generated by the current i1 flowing through R2 and the voltage generated by the current i 1+ i 2 flowing through R3, the gain is 1 because the instrumentation amplifier is not designed with a gain resistor, the output voltage is U + minus U-, the final result is found to be R multiplied by i1 through calculation, and the voltages generated by the long wire resistances are mutually cancelled through positive and negative phases. The output end of the instrument amplifier is connected with the ADC circuit, so that the analog quantity is converted into digital quantity through the ADC circuit, and then the digital quantity is processed through the MCU to obtain the strain force.
The utility model discloses during the foil gage of surveying inserts two the same constant current circuits with three equal long wires, the test result that the signal obtained behind the instrumentation amplifier can offset the influence of long wire resistance to measurement accuracy. The device has reasonable design and convenient use, and greatly improves the accuracy of measured data.
The present invention is not limited to the above embodiments, and based on the technical solutions of the present disclosure, those skilled in the art can make some substitutions and transformations to some technical features without creative labor according to the disclosed technical contents, and these substitutions and transformations are all within the protection scope of the present invention.
Claims (5)
1. The utility model provides a can eliminate strain measurement circuit of long wire influence which characterized in that: the output current of the first constant current circuit is equal to that of the second constant current circuit, the output ends of the first constant current circuit and the second constant current circuit are respectively connected with the two input ends of the offset amplifying circuit, the two input ends of the offset amplifying circuit are connected with the two ends of the tested strain gage R, the output of the amplifying circuit is connected with the ADC circuit, and the ADC circuit is connected with the MCU.
2. The strain measurement circuit capable of eliminating the influence of a long wire according to claim 1, wherein: the first constant current circuit comprises a reference power supply chip U1 and a reference power supply chip U1V IN The end is connected with the positive pole of the direct current power supply, the negative pole of the direct current power supply is grounded, and the voltage of the reference power supply chip U1 is V OUT The end of the current limiting resistor R1 is connected with one end of a current limiting resistor R1, and the other end of the current limiting resistor R1 is connected with the GND end of the direct-current power supply and one input end of the amplifying circuit respectively;
the second constant current circuit comprises a reference power supply chip U2 and a reference power supply chip U2V IN The end is connected with the positive pole of the direct current power supply, the negative pole of the direct current power supply is grounded, and the voltage of the reference power supply chip U2 is V OUT One end of the current limiting resistor R2 is connected with the other end of the current limiting resistor R2 is respectively connected withThe GND end of the direct current power supply is connected with the other input end of the amplifying circuit.
3. The strain measurement circuit capable of eliminating the influence of a long wire according to claim 2, wherein: the amplifying circuit comprises an instrument amplifier A1, wherein the non-inverting input end of the instrument amplifier A1 is connected with the other end of a current-limiting resistor R1, the inverting input end of the instrument amplifier A1 is connected with the other end of a current-limiting resistor R2, one end of a measured strain gage R is connected with the other end of a current-limiting resistor R1 through a long lead 1, the other end of the measured strain gage R is connected with the other end of a current-limiting resistor R2 through a long lead 2, the other end of the measured strain gage R is grounded through a long lead 3, the output end of the instrument amplifier A1 is connected with an ADC circuit, and the resistance values of the long lead 1, the long lead 2 and the long lead 3 are the same.
4. The strain measurement circuit capable of eliminating the influence of a long wire according to claim 3, wherein: the resistance values of the long wires 1, 2, and 3 are not more than 20 Ω.
5. The strain measurement circuit capable of eliminating the influence of a long wire according to claim 4, wherein: the output current of the first constant current circuit and the second constant current circuit is not more than 10 mA.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221334595.0U CN217384131U (en) | 2022-05-31 | 2022-05-31 | Strain measuring circuit capable of eliminating influence of long wire |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221334595.0U CN217384131U (en) | 2022-05-31 | 2022-05-31 | Strain measuring circuit capable of eliminating influence of long wire |
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| Publication Number | Publication Date |
|---|---|
| CN217384131U true CN217384131U (en) | 2022-09-06 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202221334595.0U Active CN217384131U (en) | 2022-05-31 | 2022-05-31 | Strain measuring circuit capable of eliminating influence of long wire |
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2022
- 2022-05-31 CN CN202221334595.0U patent/CN217384131U/en active Active
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