CN110333014A - Strain gauge based strain measurement circuit - Google Patents

Abstract

The invention discloses a strain gauge-based strain measurement circuit. The strain gauge circuit includes: a bridge circuit, the bridge circuit includes a strain gauge and a plurality of resistors, and the strain gauge is connected to a plurality of resistors through wires; an amplifying circuit, amplifying The input positive terminal and the input negative terminal of the circuit are respectively connected with the bridge circuit, and the amplifying circuit is used to amplify the input measurement voltage signal to obtain the amplified measurement voltage signal; offset compensation resistor; processor, the input terminal of the processor and The output end of the amplifying circuit is connected, the output end of the processor is connected with the positive input end of the amplifying circuit through the offset compensation resistor, and the processor is used for receiving the amplified measurement voltage signal and outputting the offset compensation voltage signal. The strain measurement circuit of the embodiment of the present invention can effectively measure and compensate the error caused by the wire connecting the strain gauge and multiple resistors, thereby improving the measurement accuracy.

Description

Strain gauge based strain measurement circuit

technical field

The invention relates to the technical field of strain measurement, in particular to a strain gauge-based strain measurement circuit.

Background technique

In strain measurement, it is the most common way to use strain gauges to form a Wheatstone bridge for measurement, but it is difficult to install the processing circuit near the position of the strain gauges in engineering implementation, resulting in only the strain gauges and the processing circuit being connected by The measurement error caused by the longer signal transmission line cannot be ignored.

Among them, a longer signal transmission line resistance will cause a larger potential shift in the signal output by the strain gauge, resulting in a larger shift in the output of the processing circuit, and even the full output range of the strain gauge cannot be used.

Contents of the invention

The present invention aims to solve one of the technical problems in the above-mentioned technologies at least to a certain extent.

Therefore, an object of the present invention is to propose a strain gauge-based strain measurement circuit, which can effectively measure and compensate errors caused by wires connecting strain gauges and multiple resistors, thereby improving measurement accuracy.

In order to achieve the above object, the embodiment of the first aspect of the present invention proposes a strain gauge-based strain measurement circuit, including: a bridge circuit, the bridge circuit includes the strain gauge and a plurality of resistors, and the strain gauge passes through The wires are connected to the plurality of resistors; an amplifying circuit, the input positive terminal and the input negative terminal of the amplifying circuit are respectively connected to the bridge circuit, and the amplifying circuit is used to amplify the input measurement voltage signal to obtain Amplify the measurement voltage signal; offset compensation resistance; processor, the input end of the processor is connected with the output end of the amplification circuit, and the output end of the processor is connected with the output end of the amplification circuit through the offset compensation resistance The positive input terminal is connected, and the processor is used for receiving the amplified measurement voltage signal and outputting an offset compensation voltage signal.

According to the strain measuring circuit based on the strain gauge of the embodiment of the present invention, the bridge circuit includes a strain gauge and a plurality of resistors, the strain gauge is connected to a plurality of resistors through wires, and the positive input terminal and the negative input terminal of the amplifying circuit are respectively connected to the bridge circuit connected, the input measurement voltage signal is amplified through the amplifying circuit to obtain the amplified measurement voltage signal, the input terminal of the processor is connected to the output terminal of the amplifying circuit, and the output terminal of the processor is connected to the first of the amplifying circuit through an offset compensation resistor The input terminal is connected to receive the amplified measurement voltage signal through the processor, and output the offset compensation voltage signal. Therefore, the strain measurement circuit can effectively measure and compensate for errors caused by wires connecting the strain gauges and multiple resistors, thereby improving measurement accuracy.

In addition, the strain gauge-based strain measurement circuit proposed according to the above-mentioned embodiments of the present invention may also have the following additional technical features:

In an embodiment of the present invention, the plurality of resistors include: a first resistor, a second resistor and a third resistor; the first end of the first resistor is used to input a power supply voltage signal, and the first end of the first resistor The second terminal is grounded through the strain gauge, the second terminal of the first resistor is connected to the input negative terminal of the amplifying circuit; the first terminal of the second resistor is used to input the power supply voltage signal, and the The second terminal of the second resistor is grounded through the third resistor, and the second terminal of the second resistor is connected to the positive input terminal of the amplifying circuit.

In one embodiment of the present invention, the resistance value of the first resistor is equal to the resistance value of the second resistor, and the resistance value of the third resistor is equal to the resistance value of the strain gauge in an unstrained state .

In one embodiment of the present invention, the amplifying circuit includes: an amplifier, the positive input terminal of the amplifier is used as the positive input terminal of the amplifying circuit, and the negative input terminal of the amplifier is used as the negative input terminal of the amplifying circuit , the output terminal of the amplifier is used as the output terminal of the amplifying circuit, and the amplifier is used to amplify the input measurement voltage signal to obtain the amplified measurement voltage signal; the fourth resistor is the input of the amplifier The negative terminal is connected to the output terminal of the amplifier through the fourth resistor.

In one embodiment of the present invention, the processor includes: an analog-to-digital converter, the input of the analog-to-digital converter is used as the input of the processor, and the analog-to-digital converter is used to input the Amplify the measurement voltage signal to perform analog-to-digital conversion processing to obtain an amplified measurement voltage value; a digital processor, the input end of the digital processor is connected to the output end of the analog-to-digital converter, and the digital processor is used to receive the amplified Measure the voltage value, and output the offset compensation voltage value; digital-to-analog converter, the input terminal of the digital-analog converter is connected to the output terminal of the digital processor, and the output terminal of the digital-analog converter is used as the processing The digital-to-analog converter is used to perform digital-to-analog conversion processing on the input offset compensation voltage value to obtain the offset compensation voltage signal.

In one embodiment of the present invention, the above-mentioned strain gauge-based strain measurement circuit further includes: a temperature acquisition device, the temperature acquisition device is arranged on the wire, the temperature acquisition device is connected to the digital processor, the The temperature collecting device is used to collect the temperature of the wire.

In an embodiment of the present invention, the digital processor is specifically configured to: when the strain gauge is in an unstrained state, adjust the output offset compensation voltage value, and set the amplified measurement voltage value to 0 The corresponding offset compensation voltage value is used as the target offset compensation voltage value.

In an embodiment of the present invention, the digital processor is further configured to: when the strain gauge is in a strained state, adjust the output offset compensation voltage value to be equal to the target offset compensation voltage value; according to The amplified measured voltage value determines the strain amount of the strain gauge.

In an embodiment of the present invention, the digital processor is specifically configured to: when the strain gauge is in an unstrained state, at a plurality of different temperatures of the wires, respectively adjust the output offset A compensation voltage value, using the offset compensation voltage value corresponding to the amplified measurement voltage value equal to 0 as the target offset compensation voltage value corresponding to the temperature of the wire.

In an embodiment of the present invention, the digital processor is also used for: when the strain gauge is in a strained state, obtain the corresponding target offset compensation voltage value according to the temperature of the wire; adjust the output The offset compensation voltage value is equal to the corresponding target offset compensation voltage value; the strain amount of the strain gauge is determined according to the amplified measurement voltage value.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and easy to understand from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

1 is a schematic diagram of a strain gauge based strain measurement circuit according to one embodiment of the present invention; and

FIG. 2 is a schematic diagram of a strain gauge-based strain measurement circuit according to another embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

In the field of strain measurement, if the strain gauge and the processing circuit are connected by a long wire, it will inevitably cause a non-negligible measurement error during measurement. To measure and correct the error caused by the long wire, the current commonly used technical means , in addition to the four-wire connection of the strain gauge itself to eliminate the connection error, the related technology can also be compensated by adding an external circuit.

However, the above-mentioned method has the following disadvantages:

①. It is necessary to place the entire bridge circuit near the strain gauge, which is difficult to achieve in engineering implementation;

②, There are many connections, and the wiring is troublesome;

③. The error introduced by the external circuit cannot be ignored, otherwise it will inevitably affect the accuracy of the measurement.

To this end, the present invention proposes a strain gauge-based strain measurement circuit to at least partially solve one of the technical problems in the above-mentioned technologies.

The strain gauge-based strain measurement circuit according to the embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a strain gauge-based strain measurement circuit according to one embodiment of the present invention. As shown in FIG. 1 , the strain gauge-based strain measurement circuit according to the embodiment of the present invention may include: a bridge circuit 100 , an amplifier circuit 200 , an offset compensation resistor Rc and a processor 300 .

Wherein, the bridge circuit 100 may include a strain gauge 110 and a plurality of resistors 120 , and the strain gauge 100 is connected to the plurality of resistors 120 through a wire L. The positive input terminal and the negative input terminal of the amplifying circuit 200 are connected to the bridge circuit 100 respectively, and the amplifying circuit 200 is used for amplifying the input measurement voltage signal to obtain the amplified measurement voltage signal. The input end of the processor 300 is connected to the output end of the amplifying circuit 200, the output end of the processor 300 is connected to the positive input end of the amplifying circuit 200 through the offset compensation resistor Rc, and the processor 300 is used to receive the amplified measurement voltage signal, and output Offset compensated voltage signal.

It should be noted that the numbers of the multiple resistors described in the above embodiments can be calibrated according to actual conditions.

Specifically, referring to FIG. 1 , a plurality of resistors 120 and the strain gauge 100 form a bridge, and the plurality of resistors 120 may include a first resistor R1, a second resistor R2 and a third resistor Rx, wherein the first end of the first resistor R1 For inputting the supply voltage signal V+, the second terminal of the first resistor R1 is grounded through the strain gauge 110 , and the second terminal of the first resistor R1 is also connected to the input negative terminal of the amplifying circuit 200 . The first terminal of the second resistor R2 is used to input the power supply voltage signal V+, the second terminal of the second resistor R2 is grounded through the third resistor Rx, and the second terminal of the second resistor R2 can also be connected to the positive input terminal of the amplifier circuit 200 . Wherein, the resistance value of the first resistor R1 and the resistance value of the second resistor R2 may be equal, and the resistance value of the third resistor Rx may be equal to the resistance value of the strain gauge 110 in an unstrained state.

1, the amplifying circuit 200 may include an amplifier AMP and a fourth resistor Rm, wherein the positive input terminal of the amplifier AMP is used as the positive input terminal of the amplifying circuit 200, the negative input terminal of the amplifier AMP is used as the negative input terminal of the amplifying circuit 200, and the amplifier The output terminal of the AMP is used as the output terminal of the amplifier circuit 200. The amplifier AMP is used to amplify the input measurement voltage signal to obtain the amplified measurement voltage signal. The input negative terminal of the amplifier AMP is connected to the output terminal of the amplifier AMP through the fourth resistor Rm. .

Referring to Fig. 1, the processor 300 may include an analog-to-digital converter ADC (Analog-to-Digital Converter, analog-to-digital converter), a digital processor MCU (Micro Control Unit, micro control unit) and a digital-to-analog converter DAC (Digitalto analog converter, digital-to-analog converter), wherein, the input end of the analog-to-digital converter ADC is used as the input end of the processor 300, and the analog-to-digital converter ADC is used to perform analog-to-digital conversion processing on the input amplified measurement voltage signal to obtain the amplified measurement voltage value. The input terminal of the digital processor MCU is connected with the output terminal of the analog-to-digital converter ADC, and the digital processor MCU is used for receiving the amplified measurement voltage value and outputting the offset compensation voltage value. The input end of the digital-to-analog converter DAC is connected to the output end of the digital processor MCU, the output end of the digital-to-analog converter DAC is used as the output end of the processor 300, and the digital-to-analog converter DAC is used to perform the offset compensation voltage value input Digital-to-analog conversion processing to obtain an offset compensation voltage signal.

The following describes in detail how the embodiment of the present invention is based on the strain gauge strain measurement circuit to compensate the wire machine:

In one embodiment of the present invention, the digital processor MCU is specifically used to adjust the output offset compensation voltage value when the strain gauge 110 is in an unstrained state, and to amplify the corresponding offset compensation voltage when the measured voltage value is equal to 0 value as the target offset compensation voltage value.

Further, in another embodiment of the present invention, the digital processor MCU is also used to adjust the output offset compensation voltage value to be equal to the target offset compensation voltage value when the strain gauge 110 is in a strained state, and measure The voltage value determines the amount of strain in the strain gauge.

For example, referring to FIG. 1 , assuming that the current flowing through the first resistor R1 is I1, and the current flowing through the strain gauge 110 is Is, wherein the resistance value of the strain gauge 110 is Rs, the resistance value of the wire L is r, and the current flowing through The current passing through the second resistor R2 is I2, the current flowing through the fourth resistor Rm is Im, the resistance change caused by the strain is ΔR, the power supply voltage of the bridge circuit 100 is (V+)-(V-)=U, the amplifier circuit 200 The input voltage at the positive input terminal is U2, the input voltage at the negative input terminal is U1, the compensation control voltage is Uc, the output voltage of the amplifying circuit 200 is Uo, and the V-potential of the power supply is 0.

Wherein, when the strain gauge 110 is in an unstrained state, the simultaneous equations of the network composed of the second resistor R2, the third resistor Rx and the offset compensation resistor Rc are:

U2=R2*I2; U2=Rc*Ic+Uc; (I2+Ic)*Rx=U-U2; thus: U2=(R2RcU/R2-R2Uc)/(Rc+Rx+Rx*Rc/ R2), then there is a constant: b2 and k2 make U2=f(Uc)=k2Uc+b2 set up, both U2 and Uc have a linear relationship, wherein, b2=(R2RcU/R2)/(Rc+Rx+Rx*Rc /R2), k2=-R2/(Rc+Rx+Rx*Rc/R2).

When the strain gauge 110 is in a strained state, let Rs'=Rs+r+ΔR, the network simultaneous equation composed of the first resistance R1, the resistance r of the wire L, the resistance Rs of the strain gauge 110 and the resistance of the fourth resistance Rm:

U1=Rs'*Is; U1=Rm*Im+Uo; (Is+Im) R1=U-U1; thus: Uo=(UmRm-U1(R1Rm/Rs'+R1+Rm))/R1 , and then U1=U2 can be obtained from the operation amplifier principle (that is, the operation principle of the amplifier circuit 200), that is, Uo=(UmRm-f(Uc)(R1Rm/Rs'+R1+Rm))/R1, which is the same as the above when The derivation process when the strain gauge 110 is in an unstrained state, the above formula can be simplified as: Uo=b1-f(Uc)k1/Rs'=b1-f1(Uc)k1/(Rs+r+ΔR), where Rs, k1 and b1 are constants.

From the monotonicity of f1(Uc), it can be seen that there is a certain control voltage value Uc, so that when ΔR=0 in the above formula, Uo=0, to ensure that the output of Uo will not exceed the sampling of the analog-to-digital converter ADC during normal measurement The scope can adapt to the influence of the change of the length of the line (wire), so as to effectively measure and compensate the error caused by the wire connecting the strain gauge and multiple resistors, thereby improving the measurement accuracy.

In addition, in an embodiment of the present invention, as shown in FIG. 2, the above-mentioned strain gauge-based strain measurement circuit may also include a temperature acquisition device 10, which is arranged on the wire L, and the temperature acquisition device 10 is connected with the digital processing The device MCU is connected, and the temperature acquisition device 10 is used to acquire the temperature of the wire L.

In one embodiment of the present invention, the digital processor MCU is specifically used to adjust the output offset compensation voltage value respectively at the temperature of a plurality of different wires L when the strain gauge 110 is in an unstrained state, and to amplify When the measured voltage value is equal to 0, the corresponding offset compensation voltage value is used as the target offset compensation voltage value corresponding to the temperature of the wire.

Further, in another embodiment of the present invention, the digital processor MCU is also used to obtain the corresponding target offset compensation voltage value according to the temperature of the wire L when the strain gauge 110 is in a strained state, and adjust the output bias The offset compensation voltage value is equal to the corresponding target offset compensation voltage value, and the strain amount of the strain gauge is determined according to the amplified measurement voltage value.

For example, referring to FIG. 2 , assuming that the current flowing through the first resistor R1 is I1, and the current flowing through the strain gauge 110 is Is, wherein the resistance value of the strain gauge 110 is Rs, the resistance value of the wire L is r, and the current flowing through The current passing through the second resistor R2 is I2, the current flowing through the fourth resistor Rm is Im, the resistance change caused by the strain is ΔR, the power supply voltage of the bridge circuit 100 is (V+)-(V-)=U, the amplifier circuit 200 The input voltage at the positive input terminal is U2, the input voltage at the negative input terminal is U1, the compensation control voltage is Uc, the output voltage of the amplifying circuit 200 is Uo, and the V-potential of the power supply is 0.

Based on the derivation process in the above example, the temperature of the wire L is taken into consideration, wherein, when the temperature range of the wire L is not large, the resistance of the metal wire (for example, the wire L) approximately conforms to r=r0+aT, where r0 is the resistance at 0°C, a is the temperature coefficient, and T is the current temperature.

Substituting the Uo formula = in the above example, we can get Uo=b1-f(Uc)k1/Rs'=b1-f1(Uc)k1/(Rs+r0+aT+ΔR), that is, at different temperatures, there is A series of corresponding Uc, so that when the above formula is ΔR=0, Uo=0, to ensure that the output of Uo will not exceed the sampling range of the analog-to-digital converter ADC during normal measurement, and can adapt to the influence of line (conductor) length changes , so as to effectively measure and compensate the errors caused by the wires connecting the strain gauges and multiple resistors, thereby improving the measurement accuracy.

It should be noted that when the compensation control voltage Uc is a fixed value, the calibration process is:

First, confirm that the strain gauge 110 is in a stable state (that is, the resistance value of the strain gauge 110 is in a stable state), and ΔR=0. By setting the DAC value of the digital-to-analog converter, the compensation control voltage Uc is changed from low to high in a certain output range output, and collect the output value Uo of the operational amplifier (amplifying circuit 200) at the same time, and when Uo=0, save the current DAC value of the digital-to-analog converter.

Then, by repeating the above process at different temperatures, a series of compensation control voltage Uc corresponding to the temperature can be obtained. In actual use, the temperature near the wire is collected by the temperature sensor 10, and the corresponding compensation control voltage Uc is set to output The compensation can be completed.

The strain measurement based on the strain gauge in the embodiment of the present invention can compensate the error in the measurement process and is more flexible, not only can compensate the resistance of the long wire, but also can compensate the measurement error caused by temperature, and other component parameter errors in the measurement circuit The measurement error caused can also effectively reduce the number of wiring harnesses. A strain gauge only needs 2 wires, and the circuit can be easily expanded for multi-channel measurement.

In summary, according to the strain gauge-based strain measurement circuit according to the embodiment of the present invention, the bridge circuit includes a strain gauge and a plurality of resistors, the strain gauge is connected to a plurality of resistors through wires, and the positive input terminal and the negative input terminal of the amplifying circuit are respectively connected to the The bridge circuit is connected, and the input measurement voltage signal is amplified through the amplifying circuit to obtain the amplified measurement voltage signal. The input terminal of the processor is connected to the output terminal of the amplifying circuit, and the output terminal of the processor is connected to the amplifying circuit through an offset compensation resistor. The first input terminal is connected to receive the amplified measurement voltage signal through the processor, and output the offset compensation voltage signal. Therefore, the strain measurement circuit can effectively measure and compensate for errors caused by wires connecting the strain gauges and multiple resistors, thereby improving measurement accuracy.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial" , "radial", "circumferential" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the referred device or Elements must have certain orientations, be constructed and operate in certain orientations, and therefore should not be construed as limitations on the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature indirectly through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (10)

1. a kind of strain measurement circuit based on foil gauge characterized by comprising

Bridge circuit, the bridge circuit include the foil gauge and multiple resistance, and the foil gauge passes through conducting wire and described more A resistance connection；

Amplifying circuit, the input anode and input negative terminal of the amplifying circuit are connect with the bridge circuit respectively, the amplification Circuit obtains measurement by magnification voltage signal for amplifying processing to the measurement voltage signal of input；

Migration resistance；

Processor, the input terminal of the processor are connect with the output end of the amplifying circuit, and the output end of the processor is logical It crosses the migration resistance to connect with the input anode of the amplifying circuit, the processor is for receiving the measurement by magnification Voltage signal and output offset compensation voltage signal.

2. strain measurement circuit according to claim 1, which is characterized in that the multiple resistance includes: first resistor, Two resistance and 3rd resistor；

For the first end of the first resistor for inputting supply voltage signal, the second end of the first resistor passes through the strain Piece ground connection, the second end of the first resistor are connect with the input negative terminal of the amplifying circuit；

The first end of the second resistance passes through described for inputting the supply voltage signal, the second end of the second resistance 3rd resistor ground connection, the second end of the second resistance are connect with the input anode of the amplifying circuit.

3. strain measurement circuit according to claim 2, which is characterized in that the resistance value of the first resistor and described second The resistance value of resistance is equal, and the resistance value that the resistance value of the 3rd resistor and the foil gauge are under unstrained state is equal.

4. strain measurement circuit according to claim 1, which is characterized in that the amplifying circuit includes:

The input of amplifier, input anode of the input anode of the amplifier as the amplifying circuit, the amplifier is negative The input negative terminal as the amplifying circuit is held, output end of the output end of the amplifier as the amplifying circuit is described Amplifier obtains the measurement by magnification voltage signal for amplifying processing to the measurement voltage signal of input；

The input negative terminal of 4th resistance, the amplifier is connect by the 4th resistance with the output end of the amplifier.

5. strain measurement circuit according to claim 1, which is characterized in that the processor includes:

Analog-digital converter, input terminal of the input terminal of the analog-digital converter as the processor, the analog-digital converter are used In carrying out analog-to-digital conversion process to the measurement by magnification voltage signal of input, measurement by magnification voltage value is obtained；

Digital processing unit, the input terminal of the digital processing unit are connect with the output end of the analog-digital converter, at the number Reason device is for receiving the measurement by magnification voltage value and output offset offset voltage value；

Digital analog converter, the input terminal of the digital analog converter are connect with the output end of the digital processing unit, and the digital-to-analogue turns Output end of the output end of parallel operation as the processor, the digital analog converter are used for the offset compensation voltage to input Value carries out digital-to-analogue conversion processing, obtains the offset compensation voltage signal.

6. strain measurement circuit according to claim 5, which is characterized in that further include:

Temperature collecting device, the temperature collecting device are arranged on the conducting wire, the temperature collecting device and the number Processor connection, the temperature collecting device are used to acquire the temperature of the conducting wire.

7. strain measurement circuit according to claim 5, which is characterized in that the digital processing unit is specifically used for:

When the foil gauge is under unstrained state, the offset compensation voltage value of output is adjusted, the amplification is surveyed The corresponding offset compensation voltage value is as target offset offset voltage value when measuring voltage value equal to 0.

8. strain measurement circuit according to claim 7, which is characterized in that the digital processing unit is also used to:

When the foil gauge is under strain regime, the offset compensation voltage value for adjusting output is equal to the target offset Offset voltage value；

The dependent variable of the foil gauge is determined according to the measurement by magnification voltage value.

9. strain measurement circuit according to claim 6, which is characterized in that the digital processing unit is specifically used for:

When the foil gauge is under unstrained state, multiple and different conducting wires at a temperature of, respectively adjust output The offset compensation voltage value, when the measurement by magnification voltage value is equal to 0 the corresponding offset compensation voltage value as The corresponding target offset offset voltage value of the temperature of the conducting wire.

10. strain measurement circuit according to claim 9, which is characterized in that the digital processing unit is also used to:

When the foil gauge is under strain regime, the corresponding target offset is obtained according to the temperature of the conducting wire and is compensated Voltage value；

The offset compensation voltage value for adjusting output is equal to the corresponding target offset offset voltage value；

The dependent variable of the foil gauge is determined according to the measurement by magnification voltage value.