Strain distribution measurement circuit based on strain gauge

Abstract

The present invention discloses a strain distribution measurement circuit based on a strain gauge, comprising: a strain gauge array, the strain gauge array comprising N*M strain gauges arranged in a matrix of N rows and M columns; N first resistors, second resistors, M third resistors and a multi-way switch, each strain gauge forms a bridge circuit with at least one first resistor, a second resistor and at least one third resistor through the multi-way switch. The strain distribution measurement circuit of the embodiment of the present invention reduces complexity and power consumption and reduces wiring cables by setting a strain gauge array and matching a corresponding acquisition circuit.

Description

Technical Field

[0001] The invention relates to the technical field of strain distribution measurement, and in particular to a strain distribution measurement circuit based on a strain gauge. Background Art

[0002] At present, in the analysis of structural stress distribution, the commonly used measurement method is to attach multiple strain gauges on the surface of the structure for distributed measurement. However, this measurement method requires large-scale multi-channel acquisition equipment to collect the signals of the strain gauges separately. Its main disadvantages are:

[0003] 1. The acquisition equipment requires a large number of channels, the system is complex, the volume is large, and the power consumption is high;

[0004] 2. Each strain gauge requires a set of cables for connection. There are many cables, the wiring is complicated and the reliability is low. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the above-mentioned technology at least to some extent.

[0006] To this end, an object of the present invention is to propose a strain distribution measurement circuit based on strain gauges, which reduces complexity and power consumption and reduces wiring cables by setting up a strain gauge array and matching corresponding acquisition circuits.

[0007] To achieve the above-mentioned objectives, an embodiment of the first aspect of the present invention proposes a strain distribution measurement circuit based on a strain gauge, comprising: a strain gauge array, the strain gauge array comprising N*M strain gauges arranged in a matrix of N rows and M columns; N first resistors, second resistors, M third resistors and a multi-way switch, the first strain gauge forms a bridge circuit with at least one of the first resistors, the second resistor and at least one of the third resistors through the multi-way switch.

[0008] According to the strain distribution measurement circuit based on the strain gauge of the embodiment of the present invention, the strain gauge array includes N*M strain gauges arranged in a matrix of N rows and M columns, wherein each strain gauge forms a bridge circuit with at least one first resistor, a second resistor and at least one third resistor through a multi-way switch. Therefore, the strain distribution measurement circuit based on the strain gauge reduces complexity and power consumption and reduces wiring cables by setting a strain gauge array and matching corresponding acquisition circuits.

[0009] In addition, the strain distribution measurement circuit based on the strain gauge proposed in the above embodiment of the present invention may also have the following additional technical features:

[0010] In one embodiment of the present invention, the strain distribution measurement circuit based on the strain gauge further includes: N amplifying circuits; the N first resistors correspond to the strain gauges in N rows, and one end of the strain gauge is connected to the positive electrode of the power supply through the first resistor corresponding to the row; the N amplifying circuits correspond to the strain gauges in N rows, and one end of the strain gauge is also connected to the input negative end of the amplifying circuit corresponding to the row, and the amplifying circuit is used to amplify the input measurement voltage signal to obtain an amplified measurement voltage signal; the input positive end of the amplifying circuit is connected to the positive electrode of the power supply through the second resistor; the M third resistors correspond to the strain gauges in M ​​columns, and the first end of the third resistor is connected to the positive electrode of the power supply through the second resistor; the multi-way switch includes a moving contact and M static contacts, the M static contacts correspond to the strain gauges in M ​​columns, the other end of the strain gauge is connected to the static contact corresponding to the column, the second end of the third resistor is connected to the static contact corresponding to the column, and the moving contact is connected to the negative electrode of the power supply.

[0011] In one embodiment of the present invention, the resistance value of the first resistor is equal to the resistance value of the second resistor.

[0012] In one embodiment of the present invention, the resistance value of the third resistor is equal to the resistance value of the strain gauge in a non-strained state.

[0013] In one embodiment of the present invention, the third resistor is a fixed resistor or a strain gauge with the same specification as the strain gauge and which does not generate strain.

[0014] In one embodiment of the present invention, the amplifying circuit includes: an amplifier, the positive input terminal of the amplifier serves as the positive input terminal of the amplifier circuit, the negative input terminal of the amplifier serves as the negative input terminal of the amplifier circuit, the output terminal of the amplifier serves as the output terminal of the amplifier circuit, and the amplifier is used to amplify the input measurement voltage signal to obtain the amplified measurement voltage signal; and a fourth resistor, the negative input terminal of the amplifier is connected to the output terminal of the amplifier through the fourth resistor.

[0015] In one embodiment of the present invention, the voltage of the negative electrode of the power supply is equal to 0.

[0016] In one embodiment of the present invention, the multi-way switch is a mechanical switch or a semiconductor analog switch.

[0017] In one embodiment of the present invention, the above-mentioned strain distribution measurement circuit based on strain gauges also includes: N processors, the N processors corresponding to N rows of strain gauges, the input end of the processor is connected to the output end of the amplifier circuit corresponding to the row, the processor is used to receive the amplified measurement voltage signal, and determine the strain amount of the strain gauge to be measured in the row according to the amplified measurement voltage signal.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0020] Figure 1 is a schematic diagram of a strain distribution measurement circuit based on a strain gauge according to an embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of a single-channel measurement equivalent circuit of a strain distribution measurement circuit based on a strain gauge according to an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of a strain distribution measurement circuit based on a strain gauge according to another embodiment of the present invention; and

[0023] Figure 4 4 is a schematic diagram of a single-channel measurement equivalent circuit of a strain distribution measurement circuit based on a strain gauge according to another embodiment of the present invention. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0025] The following describes a strain distribution measurement circuit based on a strain gauge according to an embodiment of the present invention in conjunction with the accompanying drawings.

[0026] Figure 1 is a schematic diagram of a strain distribution measurement circuit based on a strain gauge according to an embodiment of the present invention, such as Figure 1 As shown, the strain distribution measurement circuit based on the strain gauge of the embodiment of the present invention may include: a strain gauge array 100, N first resistors R1, a second resistor R2, M third resistors R3 and a multi-way switch SW, wherein N and M may be positive integers.

[0027] The strain gauge array 100 may include N*M strain gauges STRAIN arranged in a matrix of N rows and M columns, and each strain gauge STRAIN may form a bridge circuit with at least one first resistor R1 , a second resistor R2 , and at least one third resistor R3 via a multi-way switch SW.

[0028] In one embodiment of the present invention, see Figure 1 The strain distribution measurement circuit based on strain gauges may also include N amplifying circuits 200, wherein N first resistors R1 correspond to N rows of strain gauges STRAIN, N amplifying circuits 200 correspond to N rows of strain gauges STRAIN, and one end of the strain gauge STRAIN is connected to the positive electrode of the power supply V through the first resistor R1 corresponding to the row, and one end of the strain gauge STRAIN is also connected to the input negative end of the amplifying circuit 200 corresponding to the row, and the amplifying circuit 200 is used to amplify the input measurement voltage signal to obtain an amplified measurement voltage signal. The input positive end of the amplifying circuit 200 is connected to the positive electrode of the power supply V through the second resistor R2. M third resistors R3 correspond to M columns of strain gauges STRAIN, and the first end of the third resistor R3 is connected to the positive electrode of the power supply V through the second resistor R2. The multi-way switch SW includes a moving contact and M static contacts, the M static contacts correspond to M columns of strain gauges STRAIN, the other end of the strain gauge STRAIN is connected to the static contact corresponding to the column, the second end of the third resistor R3 is connected to the static contact corresponding to the column, and the moving contact is connected to the negative electrode of the power supply V.

[0029] It should be noted that the horizontal rows (N rows) and vertical columns (M columns) of the N*M strain gauges STRAIN in the above embodiment can be expanded according to actual needs.

[0030] Optionally, the resistance value of the first resistor R1 and the resistance value of the second resistor R2 may be equal, the resistance value of the third resistor R3 and the resistance value of the strain gauge STRAIN in a non-strained state may be equal, the third resistor R3 may be a fixed resistor or a strain gauge with the same specification as the strain gauge STRAIN that does not produce strain, the voltage of the negative pole of the power supply V may be equal to 0, and the multi-way switch SW may be a mechanical switch or a semiconductor analog switch.

[0031] Specifically, see Figure 1 and Figure 2The amplifier circuit 200 may include an amplifier AMP and a fourth resistor R4, the positive input terminal of the amplifier serves as the positive input terminal of the amplifier circuit 200, the negative input terminal of the amplifier AMP serves as the negative input terminal of the amplifier circuit 200, and the output terminal of the amplifier AMP serves as the output terminal of the amplifier circuit 200. The amplifier AMP is used to amplify the input measurement voltage signal to obtain an amplified measurement voltage signal, and the negative input terminal of the amplifier AMP is connected to the output terminal of the amplifier AMP through the fourth resistor R4.

[0032] Further, see Figure 3 The strain distribution measurement circuit based on the strain gauge may further include N processors 300, wherein the N processors 300 correspond to N rows of strain gauges STRAIN, the input end of the processor 300 is connected to the output end of the amplifier circuit 200 corresponding to the row, and the processor 300 is used to receive the amplified measurement voltage signal, and determine the strain amount of the strain gauge STRAIN to be measured in the row according to the amplified measurement voltage signal. The processor 300 may include a comparator, an ADC (Analog to Digital Converter), etc.

[0033] The following describes in detail how the strain distribution measurement circuit based on the strain gauge in the embodiment of the present invention performs strain distribution measurement (i.e., measurement principle):

[0034] In an embodiment of the present invention, Figure 3 and 4 As shown, the strain gauge STRAIN is the strain gauge to be measured, the strain gauge STRAINx and the fifth resistor R5 are bypass resistors formed by other strain gauges and matching resistors in the matrix, the first resistor R1, the second resistor R2 and the third resistor R3 and the strain gauge STRAIN form a bridge circuit, R1 = R2, R3 matches the nominal resistance of the strain gauge STRAIN, and the fourth resistor R4 is the amplification factor setting. After the strain gauge signal is amplified, it can be supplied to the back end (i.e., the processor 300) for processing, such as a comparator, ADC, etc.

[0035] For example, see Figure 4 , assuming that the current flowing through the first resistor R1 is I1, the current flowing through the strain gauge STRAIN is IS, the current flowing through the second resistor R2 is I2, the resistance of the strain gauge STRAIN is RS, the resistance change caused by strain is ΔR, the bridge supply voltage (V+)-(V-)=U, the input voltage of the positive input terminal of the amplifier circuit 200 is U1, the input voltage of the negative input terminal is U2, the internal resistance of the multi-way switch SW is RSW, and the voltage is U3.

[0036] Among them, according to the strain distribution measurement circuit based on the strain gauge according to the embodiment of the present invention, it can be obtained from the operational amplifier principle (that is, the operation principle of the amplifier circuit 200) that U1=U2, so no current will flow through the strain gauge STRAINx and the fifth resistor R5, that is, bypassing the strain gauge and the resistor will not affect the measurement result.

[0037] Assuming that the voltage of the negative electrode V- of the power supply V is equal to 0 (that is, the potential is 0), the following equation can be obtained:

[0038] I1*R1+IS*(RS+ΔR)+(IS+I2)*RSW=U;

[0039] U-U1=I1*R1;

[0040] U2=I2*R3+(IS+I2)*RSW;

[0041] I1-IS=(U2-OUT) / R4;

[0042] U1=U2;

[0043] The combined solution gives OUT=U2-(IS*ΔR / R3)*R4, where U2 and IS can be approximately regarded as constants because the ΔR of the strain gauge STRAIN is a very small value relative to the nominal value, and R3=RS.

[0044] Then, from the strain gauge characteristic formula dR / R=Ks*ε, the approximate conduction formula of circuit output and strain can be obtained: OUT=U2-(IS*Ks*ε)*R4.

[0045] Finally, it can be seen from the conduction formula that the circuit output and strain are in a linear relationship. In practical applications, it can be directly calibrated or calibrated by other standard equipment.

[0046] Therefore, the strain distribution measurement circuit based on strain gauges in the embodiment of the present invention can significantly reduce the size of the wiring harness, and because fewer signal processing channels are used, the hardware system is relatively simple and easier to miniaturize, so the signal processing unit can be set nearby to reduce long lines.

[0047] In summary, according to the strain distribution measurement circuit based on the strain gauge of the embodiment of the present invention, the strain gauge array includes N*M strain gauges arranged in a matrix of N rows and M columns, wherein each strain gauge forms a bridge circuit with at least one first resistor, a second resistor and at least one third resistor through a multi-way switch. Therefore, the strain distribution measurement circuit based on the strain gauge, by setting the strain gauge array and matching the corresponding acquisition circuit, not only reduces the complexity and power consumption, but also reduces the wiring cables.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0050] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a 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. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0053] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A strain distribution measurement circuit based on a strain gauge, characterized in that: include: A strain gauge array, wherein the strain gauge array comprises N*M strain gauges arranged in a matrix of N rows and M columns; N first resistors, a second resistor, M third resistors and a multi-way switch, the M third resistors are connected to the strain gauges in the M columns, the first end of the third resistor is connected to the positive electrode of the power supply through the second resistor, the N first resistors are connected to the strain gauges in the N rows, and the N first resistors are connected to at least one third resistor through the second resistor to form a bridge circuit; wherein one end of the strain gauge is connected to the positive electrode of the power supply through the first resistor corresponding to the row, the multi-way switch includes a moving contact and M static contacts, the M static contacts correspond to the strain gauges in the M columns, the other end of the strain gauge is connected to the static contact corresponding to the column, the second end of the third resistor is connected to the static contact corresponding to the column, and the moving contact is connected to the negative electrode of the power supply.

2. The strain distribution measurement circuit according to claim 1, characterized in that: Also includes: N amplifier circuits; The N amplifying circuits correspond to the N rows of strain gauges, one end of the strain gauge is also connected to the negative input end of the amplifying circuit corresponding to the row, and the amplifying circuit is used to amplify the input measurement voltage signal to obtain an amplified measurement voltage signal; The positive input terminal of the amplifier circuit is connected to the positive electrode of the power supply through the second resistor.

3. The strain distribution measurement circuit according to claim 1 or 2, characterized in that: The resistance value of the first resistor is equal to the resistance value of the second resistor.

4. The strain distribution measurement circuit according to claim 1 or 2, characterized in that: The resistance value of the third resistor is equal to the resistance value of the strain gauge in a non-strained state.

5. The strain distribution measurement circuit according to claim 4, characterized in that: The third resistor is a fixed resistor or a strain gauge with the same specification as the strain gauge and without generating strain.

6. The strain distribution measurement circuit according to claim 2, characterized in that: The amplifying circuit comprises: An amplifier, wherein the positive input terminal of the amplifier serves as the positive input terminal of the amplifier circuit, the negative input terminal of the amplifier serves as the negative input terminal of the amplifier circuit, and the output terminal of the amplifier serves as the output terminal of the amplifier circuit, and the amplifier is used to amplify the input measurement voltage signal to obtain the amplified measurement voltage signal; A fourth resistor, the negative input terminal of the amplifier is connected to the output terminal of the amplifier through the fourth resistor.

7. The strain distribution measurement circuit according to claim 2, characterized in that: The voltage of the negative electrode of the power supply is equal to 0.

8. The strain distribution measurement circuit according to claim 2, characterized in that: The multi-way switch is a mechanical switch or a semiconductor analog switch.

9. The strain distribution measurement circuit according to claim 2, characterized in that: Also includes: N processors, the N processors corresponding to the N rows of strain gauges, the input end of the processor is connected to the output end of the amplifier circuit corresponding to the row, the processor is used to receive the amplified measurement voltage signal, and determine the strain amount of the strain gauge to be measured in the row according to the amplified measurement voltage signal.

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