Group resistance strain gauge connection state detection device

Abstract

The utility model provides a grouped resistance strain gauge connection state detection device, which comprises a power supply module, a plurality of cable connection ports and a plurality of resistance detection modules, the cable connection ports are in one-to-one correspondence with the resistance detection modules, and the cable connection ports are used for connecting the detected resistance strain gauges into the detection device; the resistance value detection module comprises an input voltage generation unit, a first reference voltage generation unit, a second reference voltage generation unit, a judgment unit and a display unit, and the judgment unit compares the input voltage with the first reference voltage and the second reference voltage to accurately obtain the connection state of the resistance strain gauge to be detected. And an indicating lamp in the display unit is lightened for reminding, so that an operator can quickly know the connection state, the fault type and the fault position of the resistance strain gauge to be detected. According to the utility model, the power-up mode of the circuit is consistent with the power-up mode in the static strength test of the solid engine housing, and the circuit abnormal condition possibly occurring when the resistance strain gauge works normally can be accurately simulated.

Description

Technical Field

[0001] This utility model belongs to the field of static strength testing technology for solid rocket motors, specifically relating to a device for detecting the connection status of a group of resistance strain gauges. Background Technology

[0002] Static strength testing of solid rocket motor casings is an important means of verifying their structural reliability. The acquisition of structural stress-strain characteristics is typically achieved by attaching traditional resistance strain gauges. This testing method requires attaching strain gauges to designated locations on the casing and transmitting signals via welded leads and test cables. Finally, the test instrument is connected to collect strain data at the corresponding locations on the engine casing. During testing, the resistance strain gauges, leads, and test cables often present the following risks: (1) Lead breakage: Insufficient mechanical strength at the weld point or cable dragging can easily lead to a break in the circuit; (2) Short circuit risk: Insufficient insulation of the leads can cause signal interference or data anomalies; (3) Connection failure: The weld between the test cable and the strain gauge breaks due to external force, resulting in signal interruption. Therefore, before each formal test or after the resistance strain gauges are connected, the connection status of each resistance strain gauge needs to be checked point by point using a multimeter.

[0003] However, with increasingly complex test conditions, tight testing schedules, and a significant increase in the number of measurement points, the efficiency and reliability of traditional strain gauge connection status detection methods face severe challenges, mainly in the following aspects: 1. Traditional methods require using a multimeter to check the continuity of resistance strain gauges point by point after welding. However, in the static strength test of solid rocket motor housings, dozens or even hundreds of resistance strain gauges often need to be arranged on the solid rocket motor housing. Manually checking the resistance strain gauges is time-consuming and labor-intensive, seriously affecting test efficiency. 2. When an open circuit or short circuit occurs, it is necessary to check the welding points, leads, and cable connections one by one. The fault location process is cumbersome, especially when the test cable drags, causing the strain gauge to fall off or the lead to break, making it difficult to quickly determine the fault point. Utility Model Content

[0004] The purpose of this invention is to address the aforementioned shortcomings of existing technologies by providing a device for detecting the connection status of grouped resistance strain gauges. Currently, rapid detection technology for grouped resistance strain gauges is not yet perfect, and there is an urgent need for a device that can achieve multi-channel synchronous detection, rapid fault location, and easy on-site operation, in order to improve the testing efficiency and reliability of solid rocket motor static strength tests.

[0005] To achieve the above objectives, the technical solution provided by this utility model is as follows:

[0006] A device for detecting the connection status of a group of resistance strain gauges, wherein the resistance strain gauges are soldered to one end of a test cable via leads; the detection device is used to detect the connection status between the resistance strain gauges, leads, and test cables, wherein the connection status includes normal continuity, short circuit, and open circuit; the detection device includes a power module, multiple cable connection ports, and resistance detection modules corresponding to each cable connection port.

[0007] The cable connection port is used to connect the strain gauge to be measured.

[0008] Each resistance detection module is used to detect the connection status of the strain gauge of the resistance to be tested on the corresponding cable connection port.

[0009] The power module is used to supply power to the detection device;

[0010] Each of the aforementioned resistance detection modules includes an input voltage generation unit, a first reference voltage generation unit, a second reference voltage generation unit, a first operational amplifier U1, a second operational amplifier U2, a judgment unit, and a display unit;

[0011] The input voltage generation unit is connected in series with the strain gauge of the resistance to be measured to generate two input voltages, which are respectively transmitted to the non-inverting input terminal of the first operational amplifier U1 and the inverting input terminal of the second operational amplifier U2.

[0012] The first reference voltage generation unit includes resistors R2 and R3 connected in series. The resistance values ​​of resistors R2 and R3 are set according to the middle and lower limits of the resistance range of normal strain gauges of the same type, respectively. The resistance value of resistor R2 is equal to the middle value, and the resistance value of resistor R3 is less than the lower limit value. The first reference voltage generation unit is used to output the voltage signal at the connection of resistors R2 and R3 as the first reference voltage and transmit it to the inverting input terminal of the first operational amplifier U1.

[0013] The first operational amplifier U1 is used to compare the input voltage with the first reference voltage, and to output a high-level signal when the input voltage is greater than the first reference voltage, and to output a low-level signal when the input voltage is less than the first reference voltage;

[0014] The second reference voltage generation unit includes resistors R4 and R5 connected in series. The resistance values ​​of resistors R4 and R5 are set according to the middle and upper limits of the resistance value range of normal strain gauges of the same type, respectively. Among them, resistor R4 is equal to the middle value, and the resistance value of resistor R5 is greater than the upper limit value. The second reference voltage generation unit is used to output the voltage signal at the connection of resistors R4 and R5 as the second reference voltage and transmit it to the non-inverting input terminal of the second operational amplifier U2.

[0015] The second operational amplifier U2 is used to compare the input voltage with the second reference voltage, and to output a high-level signal when the input voltage is less than the second reference voltage, and to output a low-level signal when the input voltage is greater than the second reference voltage;

[0016] The display unit includes a first indicator light L1, a second indicator light L2, and a third indicator light L3, wherein: the first indicator light L1 is used to indicate that the connection status is normally conductive, the second indicator light L2 is used to indicate that the connection status is open circuit, and the third indicator light L3 is used to indicate that the connection status is short circuit;

[0017] The judgment unit can control only the first indicator light L1 to light up when both the first operational amplifier U1 and the second operational amplifier U2 output high-level signals; can control only the second indicator light L2 to light up when the first operational amplifier U1 outputs a high-level signal and the second operational amplifier U2 outputs a low-level signal; and can control only the third indicator light L3 to light up when the first operational amplifier U1 outputs a low-level signal and the second operational amplifier U2 outputs a high-level signal.

[0018] Furthermore, the judgment unit includes a first NOT gate, an AND gate, and a second NOT gate connected in parallel;

[0019] The output of the first operational amplifier U1 is divided into two paths: one path is connected to the input of the first NOT gate, and the other path is connected to the first input of the AND gate; the output of the first NOT gate is connected to the positive terminal of the third indicator light L3, and the negative terminal of the third indicator light L3 is connected to the DC power supply ground GND.

[0020] The output of the second operational amplifier U2 is divided into two paths: one path is connected to the input of the second NOT gate, and the other path is connected to the second input of the AND gate; the output of the second NOT gate is connected to the positive terminal of the second indicator light L2, and the negative terminal of the second indicator light L2 is connected to the DC power supply ground GND.

[0021] The output terminal of the AND gate is connected to the positive terminal of the first indicator light L1, and the negative terminal of the first indicator light L1 is connected to the DC power supply ground terminal GND.

[0022] Furthermore, the input voltage generation unit includes a resistor R1; one end of the resistor R1 and the DC power supply ground terminal GND are connected to the cable connection port, and the other end of the resistor R1 is connected to the positive terminal of the DC power supply +VCC.

[0023] Two branches are led out from the connection point of resistor R1 and the cable connection port, respectively connected to the non-inverting input terminal of the first operational amplifier U1 and the inverting input terminal of the second operational amplifier U2, to send the generated input voltage to the first operational amplifier U1 and the second operational amplifier U2.

[0024] Furthermore, one end of resistor R2 is connected to the positive terminal of DC power supply +VCC, and the other end is connected to one end of resistor R3, and the other end of resistor R3 is connected to the ground terminal of DC power supply GND.

[0025] The connection between resistors R2 and R3 is connected to the inverting input of the first operational amplifier U1, and is used to transmit the generated first reference voltage to the first operational amplifier U1.

[0026] Furthermore, one end of resistor R4 is connected to the positive terminal of DC power supply +VCC, and the other end is connected to one end of resistor R5, and the other end of resistor R5 is connected to the ground terminal of DC power supply GND.

[0027] The connection between resistors R4 and R5 is connected to the non-inverting input of the second operational amplifier U2, and is used to transmit the generated second reference voltage to the second operational amplifier U2.

[0028] Furthermore, the positive power supply terminals of the first operational amplifier U1 and the second operational amplifier U2 are both connected to the positive terminal of the DC power supply +VCC, and the negative power supply terminals are both connected to the ground terminal of the DC power supply GND.

[0029] Furthermore, the voltage at the positive terminal +VCC of the DC power supply is +5V, and the ground terminal GND of the DC power supply is the reference zero potential of the circuit.

[0030] Furthermore, the first indicator light L1 is configured to emit green light when lit, the second indicator light L2 is configured to emit red light when lit, and the third indicator light L3 is configured to emit yellow light when lit.

[0031] Furthermore, the strain gauge to be tested is a three-wire strain gauge, which is soldered to one end of a test cable via three leads, and the other end of the test cable has a connector that matches the connection port of the cable.

[0032] Furthermore, the number of both the cable connection ports and the resistance detection module is 8;

[0033] Each of the eight cable connection ports is connected to a corresponding resistance detection module via an independent signal line. The advantages of this invention are:

[0034] 1. This utility model's resistance strain gauge connection status detection device is designed with multiple cable connection ports and multiple resistance detection modules. Each cable connection port corresponds one-to-one with a resistance detection module, enabling simultaneous detection of the connection status of multiple resistance strain gauges under test. Using this detection device to test groups of resistance strain gauges improves efficiency by three times compared to the traditional method of testing each gauge individually with a multimeter.

[0035] 2. The resistance detection module of this utility model includes an input voltage generation unit, a first reference voltage generation unit, a second reference voltage generation unit, a judgment unit, and a display unit. The judgment unit can accurately determine whether the connection status of the strain gauge under test is normal, short-circuited, or open-circuited by comparing the input voltage with the first reference voltage and the second reference voltage. The display unit illuminates three indicator lights to provide reminders, enabling the operator to quickly know the connection status of the strain gauge under test and to quickly determine the fault location on the strain gauge based on the fault type.

[0036] 3. The power supply method in this utility model is consistent with the power supply method in the static strength test of solid rocket motor casing. Therefore, it can accurately simulate the circuit abnormalities that may occur when the resistance strain gauge is working normally, and the test results are reliable.

[0037] 4. The device of this utility model includes a box, a detection circuit board composed of multiple resistance detection modules installed inside the box, and cable connection ports and indicator lights installed outside the box panel. It is small in size and light in weight, and is convenient for field testing. Attached Figure Description

[0038] Figure 1 This is a circuit diagram of the grouped resistance strain gauge connection status detection device of this utility model;

[0039] Figure 2 This is a schematic diagram of the panel of the grouped resistance strain gauge connection status detection device of this utility model;

[0040] Figure 3 This is a flowchart illustrating the use of the present invention's testing device to detect resistance strain gauges before the static strength test of a solid engine casing, as described in the embodiment. Detailed Implementation

[0041] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless explicitly specified.

[0043] The resistance strain gauge used for static strength testing of solid rocket motor casings is welded to one end of a lead wire, and the other end of the lead wire is welded to a test cable. To detect the connection status between the resistance strain gauge, lead wire, and test cable before testing, this embodiment provides a device for detecting the connection status of a group of resistance strain gauges.

[0044] Reference Figure 1 and Figure 2 The group resistance strain gauge connection status detection device includes a power module, multiple cable connection ports, and resistance detection modules corresponding to each cable connection port. The power module supplies power to the detection device. A power switch S is installed on the detection device to control the power supply.

[0045] Multiple cable connection ports are used to simultaneously connect multiple strain gauges to be measured. The cable connection ports are matched with the connectors at the ends of the test cables on the strain gauges. By plugging and connecting the test cables to the cable connection ports, the strain gauges to be measured can be quickly connected to the testing device.

[0046] Each resistance detection module is used to detect the connection status of the strain gauge under test at the corresponding cable connection port. The connection status includes normal continuity, short circuit, and open circuit. Specifically, the resistance detection module is used to obtain the resistance value of the strain gauge under test and determine the connection status based on the resistance value. For example, assuming the resistance of a normal strain gauge is 120Ω, if the resistance value of the strain gauge under test is greater than 120Ω, the connection status is determined to be open circuit; if the resistance value is less than 120Ω, the connection status is determined to be short circuit.

[0047] The single resistance detection module includes an input voltage generation unit, a first reference voltage generation unit, a second reference voltage generation unit, a first operational amplifier U1, a second operational amplifier U2, a judgment unit, and a display unit.

[0048] The input voltage generation unit is connected in series with the strain gauge of the resistance under test to generate two input voltages Vi, which are respectively transmitted to the non-inverting input of the first operational amplifier U1 and the inverting input of the second operational amplifier U2. Specifically, the input voltage generation unit includes a resistor R1. Two branches are led out from the connection point of the resistor R1 and the cable connection port, respectively connected to the non-inverting input of the first operational amplifier U1 and the inverting input of the second operational amplifier U2, to send the generated input voltages to the first operational amplifier U1 and the second operational amplifier U2.

[0049] The first reference voltage generation unit includes resistors R2 and R3 connected in series. The resistance values ​​of resistors R2 and R3 are set according to the midpoint and lower limit of the resistance range of a normal strain gauge of the same model, respectively. The resistance value of resistor R2 is equal to the midpoint, and the resistance value of resistor R3 is less than the lower limit. The first reference voltage generation unit is used to output the voltage signal at the connection point of resistors R2 and R3 as the first reference voltage V1 and transmit it to the inverting input terminal of the first operational amplifier U1. Specifically, one end of resistor R2 is connected to the positive terminal +VCC of the DC power supply, and the other end is connected to one end of resistor R3. The other end of resistor R3 is connected to the ground terminal GND of the DC power supply. The connection point of resistors R2 and R3 is connected to the inverting input terminal of the first operational amplifier U1, used to transmit the generated first reference voltage to the first operational amplifier U1.

[0050] The first operational amplifier U1 is used to compare the input voltage Vi with the first reference voltage V1, and to output a high-level signal when the input voltage Vi is greater than the first reference voltage V1, and a low-level signal when the input voltage Vi is less than the first reference voltage V1. Specifically, the positive power supply terminals of the first operational amplifier U1 are all connected to the positive terminal +VCC of the DC power supply, and the negative power supply terminals are all connected to the ground terminal GND of the DC power supply.

[0051] The second reference voltage generation unit includes resistors R4 and R5 connected in series. The resistance values ​​of resistors R4 and R5 are set according to the midpoint and upper limit of the resistance range of a normal strain gauge of the same model, respectively. The resistance of resistor R4 is equal to the midpoint, and the resistance of resistor R5 is greater than the upper limit. The second reference voltage generation unit is used to output the voltage signal at the connection point of resistors R4 and R5 as the second reference voltage and transmit it to the non-inverting input of the second operational amplifier U2. Specifically, one end of resistor R4 is connected to the positive terminal of the DC power supply +VCC, and the other end is connected to one end of resistor R5. The other end of resistor R5 is connected to the ground terminal of the DC power supply GND. The connection point of resistors R4 and R5 is connected to the non-inverting input of the second operational amplifier U2 to transmit the generated second reference voltage to the second operational amplifier U2.

[0052] The second operational amplifier U2 is used to compare the input voltage Vi with the second reference voltage V2, and to output a high-level signal when the input voltage Vi is less than the second reference voltage V2, and a low-level signal when the input voltage Vi is greater than the second reference voltage V2. Specifically, the positive power supply terminal of the second operational amplifier U2 is connected to the positive terminal +VCC of the DC power supply, and the negative power supply terminal is connected to the ground terminal GND of the DC power supply.

[0053] The voltage at the positive terminal +VCC of the DC power supply is +5V, and the ground terminal GND of the DC power supply is the reference zero potential of the circuit.

[0054] The display unit includes a first indicator light L1, a second indicator light L2, and a third indicator light L3. The first indicator light L1 indicates a normal conductive connection, the second indicator light L2 indicates an open circuit, and the third indicator light L3 indicates a short circuit. Specifically, the first indicator light L1 is configured to emit green light when lit, the second indicator light L2 is configured to emit red light, and the third indicator light L3 is configured to emit yellow light, allowing the operator to quickly determine the connection status of the strain gauge under test based on the color of the indicator lights. The judgment unit can control only the first indicator light L1 to light up when both the first operational amplifier U1 and the second operational amplifier U2 output high-level signals; can control only the second indicator light L2 to light up when the first operational amplifier U1 outputs a high-level signal and the second operational amplifier U2 outputs a low-level signal; and can control only the third indicator light L3 to light up when the first operational amplifier U1 outputs a low-level signal and the second operational amplifier U2 outputs a high-level signal. Specifically, the judgment unit includes a first NOT gate, an AND gate, and a second NOT gate connected in parallel. The output of the first operational amplifier U1 is divided into two paths: one path is connected to the input of the first NOT gate, and the other path is connected to the first input of the AND gate. The output of the first NOT gate is connected to the positive terminal of the third indicator light L3, and the negative terminal of the third indicator light L3 is connected to the DC power supply ground GND. The output of the second operational amplifier U2 is also divided into two paths: one path is connected to the input of the second NOT gate, and the other path is connected to the second input of the AND gate. The output of the second NOT gate is connected to the positive terminal of the second indicator light L2, and the negative terminal of the second indicator light L2 is connected to the DC power supply ground GND. The output of the AND gate is connected to the positive terminal of the first indicator light L1, and the negative terminal of the first indicator light L1 is connected to the DC power supply ground GND.

[0055] This utility model testing device includes a housing, with the resistance detection module located inside the housing. Multiple cable connection ports and indicator lights for each resistance detection module are located on the front panel of the housing. A power switch S is also provided on the front panel of the housing to control the power supply to the testing device. A power supply input is located on another panel of the housing, allowing for power supply via a charging plug, battery, or portable power source, providing a DC 5V voltage.

[0056] The following describes the detection principle of this invention's detection device using a common 120Ω resistance strain gauge as an example. The resistance error of this strain gauge is ±10%, resulting in a resistance range of 108-132Ω. Considering the influence of wire resistance and measurement errors, the range is broadened; a resistance value between 100Ω and 150Ω is considered normal, while values ​​greater than 150Ω or less than 100Ω are considered abnormal. In this example, the strain gauge is a three-wire system, with three leads soldered to one end of a test cable. The other end of the test cable has a connector that matches the cable connection port on the detection device, allowing for quick connection of the strain gauge to the device. This example uses eight cable connection ports and eight resistance detection modules. Each of the eight cable connection ports is connected to its corresponding resistance detection module via an independent signal line, allowing simultaneous detection of the connection status of eight strain gauges.

[0057] To improve detection sensitivity, resistor R1 in the input voltage generation unit is set to 120Ω. Adjustable resistors can be used to accommodate various strain gauge values. Resistors R2 and R4 are set to 120Ω, R3 to 100 ohms, and R5 to 150 ohms. Indicator L1 illuminates green, indicator L2 illuminates red, and indicator L3 illuminates yellow.

[0058] Reference Figure 2 Procedure. During testing, the strain gauge to be tested is connected to the cable connection port of the testing device via a connector matching its test cable. The power switch S of the testing device is turned on, and the circuit operates. The color of the corresponding indicator light quickly determines whether the strain gauge is properly connected, accurately locating the fault location and type of the strain gauge. The detection principle of the resistance detection module in the testing device is as follows:

[0059] When the resistance of the strain gauge under test is less than 100 ohms, the first reference voltage V1 is greater than the input voltage Vi. Operational amplifier U1 outputs a low level, which is converted to a high level after passing through the first NOT gate, and the third indicator light L3 illuminates in yellow. At this time, the second reference voltage V2 is greater than the input voltage Vi, and operational amplifier U2 outputs a high level, which is converted to a low level after passing through the second NOT gate, and the second indicator light L2 does not illuminate. Simultaneously, since the output of operational amplifier U1 is low and the output of operational amplifier U2 is high, the output after passing through the AND gate is low, and the first indicator light L1 does not illuminate. Only the third indicator light L3 is illuminated, indicating that the strain gauge under test is short-circuited.

[0060] When the resistance of the strain gauge is greater than 100 ohms and less than 150 ohms, the first reference voltage V1 is less than the input voltage Vi, and the operational amplifier U1 outputs a high level. After passing through the first NOT gate, it is converted to a low level, and the third indicator light L3 does not light up. At this time, the second reference voltage V2 is greater than the input voltage Vi, and the operational amplifier U2 outputs a high level. After passing through the second NOT gate, it is converted to a low level, and the second indicator light L2 does not light up. Simultaneously, since the outputs of operational amplifiers U1 and U2 are both high, the output after passing through the AND gate is high, and the first indicator light L1 lights up green. The fact that only the first indicator light L1 is lit indicates that the connection of the strain gauge under test is normal.

[0061] When the resistance of the strain gauge is greater than 150 ohms, the first reference voltage V1 is less than the input voltage Vi, and the operational amplifier U1 outputs a high level, which is converted to a low level by the first NOT gate, and the third indicator light L3 does not light up. At this time, the second reference voltage V2 is less than the input voltage Vi, and the operational amplifier U2 outputs a low level, which is converted to a high level by the second NOT gate, and the second indicator light L2 lights up red. At the same time, since the output of operational amplifier U1 is high and the output of operational amplifier U2 is low, the output after the AND gate is low, and the first indicator light L1 lights up. If only the second indicator light L2 lights up red, it indicates that the connection state of the strain gauge under test is open circuit.

[0062] Troubleshooting: If the test results show a short circuit, check if the leads on the strain gauge are properly insulated; if the test results show an open circuit, check if the welding positions between the strain gauge and the leads, and between the leads and the test cable, are securely fixed. After troubleshooting, retest the strain gauges using this invention's testing device until all strain gauge connections attached to the solid engine housing are normal before proceeding with the subsequent static strength test of the solid engine housing.

[0063] This utility model relates to a group resistance strain gauge connection status detection device. It employs a method of synchronously energizing multiple resistance detection circuits to simultaneously test multiple strain gauges. This solves the problems of poor contact and errors inherent in traditional point-by-point testing of strain gauge connections using a multimeter. It achieves accurate testing in a single operation, significantly improving the efficiency of strain testing in solid rocket motor static strength tests. Furthermore, the working principle of this group resistance strain gauge detection device is consistent with the connection and energizing methods used in actual formal testing, accurately simulating potential circuit anomalies during normal operation and demonstrating superior detection performance.

[0064] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model.

Claims

1. A device for detecting the connection status of a group of resistance strain gauges, wherein the resistance strain gauges are welded to one end of a test cable via leads; characterized in that, The detection device is used to detect the connection status between the resistance strain gauge, leads and test cables. The connection status includes normal continuity, short circuit and open circuit. The detection device includes a power module, multiple cable connection ports and a resistance detection module corresponding to each cable connection port. The cable connection port is used to connect the strain gauge to be measured. Each resistance detection module is used to detect the connection status of the strain gauge of the resistance to be tested on the corresponding cable connection port. The power module is used to supply power to the detection device; Each of the aforementioned resistance detection modules includes an input voltage generation unit, a first reference voltage generation unit, a second reference voltage generation unit, a first operational amplifier U1, a second operational amplifier U2, a judgment unit, and a display unit; The input voltage generation unit is connected in series with the strain gauge of the resistance to be measured to generate two input voltages, which are respectively transmitted to the non-inverting input terminal of the first operational amplifier U1 and the inverting input terminal of the second operational amplifier U2. The first reference voltage generation unit includes resistors R2 and R3 connected in series. The resistance values ​​of resistors R2 and R3 are set according to the middle and lower limits of the resistance range of normal strain gauges of the same type, respectively. The resistance value of resistor R2 is equal to the middle value, and the resistance value of resistor R3 is less than the lower limit value. The first reference voltage generation unit is used to output the voltage signal at the connection of resistors R2 and R3 as the first reference voltage and transmit it to the inverting input terminal of the first operational amplifier U1. The first operational amplifier U1 is used to compare the input voltage with the first reference voltage, and to output a high-level signal when the input voltage is greater than the first reference voltage, and to output a low-level signal when the input voltage is less than the first reference voltage; The second reference voltage generation unit includes resistors R4 and R5 connected in series. The resistance values ​​of resistors R4 and R5 are set according to the middle and upper limits of the resistance value range of normal strain gauges of the same type, respectively. Among them, resistor R4 is equal to the middle value, and the resistance value of resistor R5 is greater than the upper limit value. The second reference voltage generation unit is used to output the voltage signal at the connection of resistors R4 and R5 as the second reference voltage and transmit it to the non-inverting input terminal of the second operational amplifier U2. The second operational amplifier U2 is used to compare the input voltage with the second reference voltage, and to output a high-level signal when the input voltage is less than the second reference voltage, and to output a low-level signal when the input voltage is greater than the second reference voltage; The display unit includes a first indicator light L1, a second indicator light L2, and a third indicator light L3, wherein: the first indicator light L1 is used to indicate that the connection status is normally conductive, the second indicator light L2 is used to indicate that the connection status is open circuit, and the third indicator light L3 is used to indicate that the connection status is short circuit; The judgment unit can control only the first indicator light L1 to light up when both the first operational amplifier U1 and the second operational amplifier U2 output high-level signals; can control only the second indicator light L2 to light up when the first operational amplifier U1 outputs a high-level signal and the second operational amplifier U2 outputs a low-level signal; and can control only the third indicator light L3 to light up when the first operational amplifier U1 outputs a low-level signal and the second operational amplifier U2 outputs a high-level signal.

2. The device for detecting the connection status of a group of resistance strain gauges according to claim 1, characterized in that, The judgment unit includes a first NOT gate, an AND gate, and a second NOT gate arranged in parallel; The output of the first operational amplifier U1 is divided into two paths: one path is connected to the input of the first NOT gate, and the other path is connected to the first input of the AND gate; the output of the first NOT gate is connected to the positive terminal of the third indicator light L3, and the negative terminal of the third indicator light L3 is connected to the DC power supply ground GND. The output of the second operational amplifier U2 is divided into two paths: one path is connected to the input of the second NOT gate, and the other path is connected to the second input of the AND gate; the output of the second NOT gate is connected to the positive terminal of the second indicator light L2, and the negative terminal of the second indicator light L2 is connected to the DC power supply ground GND. The output terminal of the AND gate is connected to the positive terminal of the first indicator light L1, and the negative terminal of the first indicator light L1 is connected to the DC power supply ground terminal GND.

3. The device for detecting the connection status of a group of resistance strain gauges according to claim 1 or 2, characterized in that, The input voltage generation unit includes a resistor R1; One end of resistor R1 and the DC power supply ground terminal GND are connected to the cable connection port, and the other end of resistor R1 is connected to the positive terminal of DC power supply +VCC. Two branches are led out from the connection point of resistor R1 and the cable connection port, respectively connected to the non-inverting input terminal of the first operational amplifier U1 and the inverting input terminal of the second operational amplifier U2, to send the generated input voltage to the first operational amplifier U1 and the second operational amplifier U2.

4. The device for detecting the connection status of a group of resistance strain gauges according to claim 3, characterized in that, One end of resistor R2 is connected to the positive terminal of DC power supply +VCC, and the other end is connected to one end of resistor R3. The other end of resistor R3 is connected to the ground terminal of DC power supply GND. The connection between resistors R2 and R3 is connected to the inverting input of the first operational amplifier U1, and is used to transmit the generated first reference voltage to the first operational amplifier U1.

5. The device for detecting the connection status of a group of resistance strain gauges according to claim 4, characterized in that, One end of resistor R4 is connected to the positive terminal of DC power supply +VCC, and the other end is connected to one end of resistor R5. The other end of resistor R5 is connected to the ground terminal of DC power supply GND. The connection between resistors R4 and R5 is connected to the non-inverting input of the second operational amplifier U2, and is used to transmit the generated second reference voltage to the second operational amplifier U2.

6. The device for detecting the connection status of a group of resistance strain gauges according to claim 5, characterized in that, The positive power supply terminals of the first operational amplifier U1 and the second operational amplifier U2 are both connected to the positive terminal of the DC power supply +VCC, and the negative power supply terminals are both connected to the ground terminal of the DC power supply GND.

7. The device for detecting the connection status of a group of resistance strain gauges according to claim 6, characterized in that, The voltage at the positive terminal +VCC of the DC power supply is +5V, and the ground terminal GND of the DC power supply is the reference zero potential of the circuit.

8. The device for detecting the connection status of a group of resistance strain gauges according to claim 1 or 2, characterized in that, The first indicator light L1 is configured to emit green light when lit, the second indicator light L2 is configured to emit red light when lit, and the third indicator light L3 is configured to emit yellow light when lit.

9. The device for detecting the connection status of a group of resistance strain gauges according to claim 1 or 2, characterized in that, The strain gauge to be tested is a three-wire strain gauge, which is soldered to one end of a test cable with three leads. The other end of the test cable has a connector that matches the cable connection port.

10. The device for detecting the connection status of a group of resistance strain gauges according to claim 1 or 2, characterized in that, The number of cable connection ports and the number of resistance detection modules are both 8; Each of the eight cable connection ports is connected to a corresponding resistance detection module via an independent signal line.

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