Strain gauge resistance value batch automatic measurement device and method

Abstract

The invention discloses a strain gauge resistance value batch automatic measurement device and method, the device comprises a measurement template, a measurement circuit and a microcontroller, the measurement template is used for bearing a measured strain gauge array and communicating the strain gauge array with the measurement circuit, and the front surface of the first layer of the measurement template is provided with probe pairs arranged in an array; a positive lead is arranged on the front surface of the second layer of the measurement template, and a negative lead, a positive lead interface and a negative lead interface are arranged on the back surface of the second layer of the measurement template; the measuring circuit is used for measuring the resistance value of the strain gauge and comprises a positive multiplexing switch, a negative multiplexing switch, a current measurer and a measuring power supply; the microcontroller controls the positive multiplexing switch and the negative multiplexing switch to gate the probe pairs corresponding to the strain gauges, collects the current measurement results of the current measurer, and calculates the resistance values of the strain gauges according to the current measurement results. According to the invention, batch automatic detection of the resistance values of the strain gauges can be realized, and the detection efficiency and the detection accuracy are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of strain gauges, and particularly relates to a device and method for batch automatic measurement of strain gauge resistance values. Background Art

[0002] The working principle of a resistance strain gauge is based on the influence of strain on resistance. When an external force or strain acts on the resistance strain gauge, the metal sensitive grid wire deforms, thereby causing a change in the resistance value, and further reflecting the stress or deformation received by the object. The traditional methods for measuring the resistance value of a resistance strain gauge mainly include two types: one is to manually observe through a microscope and manually measure by using a probe to contact the welding points at both ends of the grid wire, or to use an ohmmeter or other resistance measuring instruments, and connect the measuring probe to the welding points at both ends of the resistance strain gauge for testing. However, the accuracy of the manual detection method is unstable and the repeatability is poor. The other is to use an automated probe station for automated detection. The automated probe station can control the positioning of the probe through a computer to achieve precise contact and automatically complete the measurement of the resistance value. However, the existing automated probe stations usually require complex mechanical structures and multi-axis control systems, with high equipment costs, and the installation and debugging processes are cumbersome. In addition, the automated probe station can achieve precise single tests, but in a large-scale production environment, the efficiency of batch testing is still not high. Each device needs to be positioned and tested one by one. Although the robotic arm can perform this task precisely, the operation speed is still relatively slow. Summary of the Invention

[0003] The object of the present invention is to provide a device and method for batch automatic measurement of strain gauge resistance values to solve the defects existing in the prior art, which can achieve batch automatic detection of strain gauge resistance values, improve the detection efficiency and the detection accuracy.

[0004] To achieve the above object, one aspect of the present invention provides a device for batch automatic measurement of strain gauge resistance values, including a measurement template, a measurement circuit, and a microcontroller. The measurement template is used to carry the array of strain gauges to be measured and connect the strain gauge array to the measurement circuit. The measurement template includes a first layer and a second layer. On the front surface of the first layer of the measurement template, there are probe pairs arranged in an array, and the arrangement mode of the probe pairs matches the arrangement mode of the strain gauges in the array of strain gauges to be measured. The probe pair includes a positive probe and a negative probe, and the positive probe and the negative probe are respectively used to connect to the positive pad and the negative pad of each strain gauge. On the front surface of the second layer of the measurement template, there is a positive lead wire, and on the back surface of the second layer of the measurement template, there is a negative lead wire. The positive probes are sequentially connected through the positive lead wire to form a positive probe row, and the negative probes are sequentially connected through the negative lead wire to form a negative probe column. On the reverse side of the second layer of the measurement template, a positive lead interface and a negative lead interface are further provided. Each positive lead is connected to the positive lead interface, and each negative lead is connected to the negative lead interface; The measurement circuit is used to measure the resistance value of the strain gauge. The measurement circuit includes a positive multiplexer switch, a negative multiplexer switch, a current measurer, and a measurement power supply; The input port of the positive multiplexer switch is connected to the positive lead interface, and the output port is connected to the measurement power supply. The input port of the negative multiplexer switch is connected to the negative lead interface, and the output port is connected to the current measurer. The positive multiplexer switch is used to select the positive probe row, and the negative multiplexer switch is used to select the negative probe column; The microcontroller is connected to the positive multiplexer switch, the negative multiplexer switch, and the current measurer, and is used to control the positive multiplexer switch and the negative multiplexer switch to select the probe pairs corresponding to each strain gauge, collect the current measurement results of the current measurer, and calculate the resistance value of the strain gauge according to the current measurement results.

[0005] Preferably, blind holes are respectively provided on the first layer and the second layer of the measurement template, and through holes penetrating the first layer and the second layer are provided on the measurement template; The positive probe is connected to the positive lead through the blind hole on the first layer, and the negative probe is connected to the negative lead through the through hole; Each positive lead is connected to the positive lead interface through the blind hole on the second layer.

[0006] Preferably, the measurement template includes multiple styles for matching strain gauge arrays of different specifications and shapes; each probe pair is movably arranged on the measurement template and can be arranged according to the arrangement mode of the strain gauges in the strain gauge array.

[0007] Preferably, positioning marks are further provided on the front surface of the first layer of the measurement template, and the positioning marks are used to position each strain gauge in the strain gauge array.

[0008] Preferably, the height of the probe pair is higher than the front surface of the first layer of the measurement template.

[0009] Preferably, the height of the probe pair is 5 μm to 1 mm.

[0010] Preferably, an operational amplifier is provided between each positive probe row and the positive multiplexer switch for impedance matching and isolating interference from the measurement voltage.

[0011] Preferably, the positive lead interface and the negative lead interface are pin headers or pads.

[0012] Another aspect of the present invention provides a method for batch automatic measurement of the resistance value of a strain gauge. Using the above device for batch automatic measurement of the resistance value of a strain gauge, the method includes: Select a matching measurement template according to the shape, specifications of the strain gauge array to be measured, and the arrangement of the strain gauges; Assemble the strain gauge array to be measured on the measurement template, so that the positive pads and negative pads of each strain gauge are connected to the positive probes and negative probes of the corresponding probe pairs on the measurement template; Control the positive multiplexer switch and the negative multiplexer switch through the microcontroller to select the corresponding probe pairs of each strain gauge, collect the current measurement results of the current measurer, and calculate the resistance value of the strain gauge according to the current measurement results.

[0013] Preferably, the method further includes: Construct a resistance value matrix according to the resistance value data of each strain gauge, analyze the resistance value matrix, and determine the abnormal resistance value analysis result; Determine the corresponding abnormal strain gauge according to the abnormal resistance value analysis result; Store the resistance value analysis result corresponding to the abnormal strain gauge in the database.

[0014] According to the strain gauge resistance value batch automatic measurement device and method of the above aspect of the present invention, batch automatic detection of the strain gauge resistance value can be realized, the detection efficiency is improved, and the detection accuracy is improved. Brief Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings: Figure 1 It is a schematic diagram of a strain gauge resistance value batch automatic measurement device according to an embodiment of the present invention; Figure 2 It is a schematic diagram of the front side of the first layer of a measurement template according to an embodiment of the present invention; Figure 3 It is a schematic diagram of the front side of the second layer of a measurement template according to an embodiment of the present invention; Figure 4 It is a schematic diagram of the back side of the second layer of a measurement template according to an embodiment of the present invention; Figure 5 It is a schematic diagram of the front side of the first layer of a measurement template according to another embodiment of the present invention; Figure 6 It is a schematic diagram of the front side of the second layer of a measurement template according to another embodiment of the present invention; Figure 7 It is a schematic diagram of the back side of the second layer of a measurement template according to another embodiment of the present invention; Figure 8A longitudinal sectional view of a measurement template according to an embodiment of the present invention; Figure 9 A circuit diagram for measuring the resistance value of a certain strain gauge according to an embodiment of the present invention. Detailed implementation manners

[0016] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative efforts shall fall within the protection scope of the present invention.

[0017] An embodiment of the present invention provides a batch automatic measurement device for strain gauge resistance values. Refer to Figure 1 As shown, the automatic measurement device according to the embodiment of the present invention includes a microcontroller 1, a measurement circuit and a measurement template 6. Among them, the measurement template 6 is replaceable and is used to carry a strain gauge array and connect the strain gauge array to the measurement circuit.

[0018] Refer to Figure 2 、 Figure 3 、 Figure 4 As shown, probe pairs are arranged in an array on the measurement template 6. The arrangement manner of the probe pairs matches the arrangement manner of the strain gauges in the measured strain gauge array. Each probe pair corresponds to the pads of each strain gauge in the strain gauge array and is used to connect to the two pads of each strain gauge. Among them, the probe pair includes a positive probe 8 and a negative probe 9, which are respectively used to connect to the positive pad and the negative pad of each strain gauge. The positive probes 8 are sequentially connected to form a positive probe row, and the negative probes 9 are sequentially connected to form a negative probe column.

[0019] The measurement circuit is used to measure the resistance value of the strain gauge. Refer to Figure 1 As shown, the measurement circuit includes a positive multiplexer switch 4, a negative multiplexer switch 3, a current measurer 2, and a measurement power supply 5. Among them, the positive multiplexer switch 4 is connected to the positive probe 8 and the measurement power supply 5, and the negative multiplexer switch 4 is connected to the negative probe 9 and the current measurer 2. The positive multiplexer switch 4 and the negative multiplexer switch 3 are used to select and connect each strain gauge on the strain gauge array.

[0020] The microcontroller 1 is connected to the positive multiplexer switch 4, the negative multiplexer switch 3 and the current measurer 2, and is used to control the positive multiplexer switch 4 and the negative multiplexer switch 3 to select and connect the probe pairs corresponding to each strain gauge, collect the current measurement results of the current measurer 2, and calculate the resistance value of the strain gauge according to the current measurement results.

[0021] Exemplarily, N probe pairs are provided on the upper surface of the measurement template 6, corresponding to N strain gauges. After the positive probe 8 is sequentially connected, it is respectively connected to the positive multiplexing switch 4. After the negative probe 9 is sequentially connected, it is respectively connected to the negative multiplexing switch 3. The microcontroller 1 controls the positive multiplexing switch 4 and the negative multiplexing switch 3 to select the positive probe 8 and the negative probe 9 to perform the resistance measurement of the corresponding strain gauge.

[0022] The arrangement of the probe pairs on the measurement template 6 matches the arrangement of the respective strain gauges in the strain gauge array. For example, referring to Figure 1 and Figure 2 as shown, in the probe pair array, for the positive probes 8 in each row of probe pairs, the positive probes 8 in that row can be sequentially connected to form a row of positive probes, and then connected to the positive multiplexing switch 4. The positive multiplexing switch 4 is connected to each row of positive probes. By controlling the positive multiplexing switch 4, a row of positive probes 8 can be selected.

[0023] Similarly, in the probe pair array, for the negative probes 9 in the probe pairs, the negative probes 9 in that column can be sequentially connected to form a column of negative probes. Then it is connected to the negative multiplexing switch 3. The negative multiplexing switch 3 is connected to multiple columns of negative probes. By controlling the negative multiplexing switch 3, a column of negative probes 9 can be selected.

[0024] By using the positive multiplexing switch 4 to select a row of positive probes 8 and using the negative multiplexing switch 3 to select a column of negative probes 9, the selection of a certain probe pair can be achieved, so as to sequentially measure the resistance value of the strain gauge.

[0025] The measurement template 6 includes two layers of structures, namely the first layer and the second layer. Referring to Figure 2 as shown, on the front surface of the first layer of the measurement template 6, probe pairs are arranged in an array. The probe pairs are used to connect to the two pads of each strain gauge in the strain gauge array. The probe pair includes a positive probe 8 and a negative probe 9. The positive probe 8 and the negative probe 9 are respectively used to connect to the positive pad and the negative pad of each strain gauge.

[0026] Referring to Figure 3 , Figure 4 and Figure 8 as shown, on the front surface of the second layer of the measurement template 6, a positive lead 10 is provided. The positive lead 10 is used to connect the positive probes in the same row and form a row of positive probes. On the back surface of the second layer of the measurement template 6, a negative lead interface 12, a positive lead interface 14, and a negative lead 13 are provided. The positive lead interface 14 and the negative lead interface 12 are provided on adjacent sides of the measurement template. The positive lead interface 14 and the negative lead interface 12 can be pin headers and / or pads.

[0027] The measurement template 6 is provided with through holes 15 that penetrate the first layer and the second layer, and blind holes 11 are respectively provided on the first layer and the second layer of the measurement template 6. The blind holes 11 are used to realize the connection between the positive probe 8 and the positive lead 10 and between the positive lead 10 and the positive lead interface 14.

[0028] The negative lead 13 is used to connect the negative probes in the same column and form a negative probe column. The through holes 15 are used to realize the connection between the negative probes and the negative leads. Each positive lead 10 is connected to the positive lead interface 14, and each negative lead 13 is connected to the negative lead interface 12. The negative lead interface 12 and the positive lead interface 14 are used to realize the connection between the measurement template and the measurement circuit.

[0029] Exemplarily, the measurement template 6 is further provided with positioning marks 7 for positioning the strain gauge array, and the positioning marks 7 can be symmetrically arranged around the probe pair.

[0030] By means of the positioning marks 7 provided on the measurement template 6, the strain gauge array can be quickly arranged on the measurement template 6, and the resistance pads of each single strain gauge can be aligned with the positive probes 8 and negative probes 9 on the measurement template 6. In some embodiments, as Figure 2 shown, the number of probe pairs in the probe pair array on the measurement template 6 is set to 20 * 12; correspondingly, the styles and the number of interfaces of the positive lead interface 14 and the negative lead interface 12 can be configured according to the number of probe pairs.

[0031] Exemplarily, an operational amplifier is provided between each positive probe row and the positive multiplexer switch 4 for impedance matching and interference isolation, isolating the interference from the measured voltage, so that the detected resistance value is more accurate.

[0032] Exemplarily, the measurement template can be composed of a PCB board; on the front of the first layer of the PCB board, there are probe pairs and positioning marks arranged in an array; on the front of the second layer of the PCB board, there are positive leads; on the back of the second layer of the PCB board, there are positive lead interfaces, negative lead interfaces, and negative leads; the PCB board is provided with through holes; blind holes are provided on the first layer and the second layer of the PCB board.

[0033] Exemplarily, the measurement template 6 can be pre-configured in multiple styles for matching strain gauge arrays of different specifications and shapes. Refer to Figure 5 、 Figure 6 and Figure 7As shown, the measurement template 6 can be a circular structure. Among them, within the probe pair array of the measurement template 6, the probe pair composed of the positive probe 8 and the negative probe 9 can be movably arranged and can be matched according to the arrangement pattern of the strain gauges in the strain gauge array. The positioning mark 7, the negative lead interface 12, the positive lead interface 14, the positive lead 10, the negative lead 13, the through hole 15, and the blind hole 11 can be adjusted and set according to the arrangement pattern of the strain gauges.

[0034] Exemplarily, referring to Figure 9 As shown, when measuring the strain gauge resistance, a corresponding measurement template can be selected according to the array strain gauges of different sizes. The microcontroller can identify the measurement template identification code, determine the number of probes, and send a control signal to the address selection ports of the positive multiplexer switch and the negative multiplexer switch. The positive multiplexer switch and the negative multiplexer switch, according to the control signal, such as the positive multiplexer switch (000) control signal and the negative multiplexer switch (000) control signal, conduct the measurement circuit of the No. 1 strain gauge; the current measurer detects the current signal of the conducted circuit and sends it to the microcontroller; the microcontroller calculates the strain gauge resistance value according to Ohm's law based on the known voltage value of the measurement power supply and the detected current value. By changing the control signals sent by the microcontroller to the positive multiplexer switch and the negative multiplexer switch, the measurement circuits of different strain gauges can be conducted; repeat the above process until the resistance values of all the strain gauges in the array strain gauges are measured.

[0035] Exemplarily, the heights of the positive probe and the negative probe on the measurement template are higher than the front surface of the first layer of the measurement template. Specifically, the solder pad heights of the probe pairs on the template can be correspondingly configured according to the size of the measurement template. For example, when the measurement template is a PCB template and the board length is less than 200 mm, the allowable warpage value is 0.75%, then the height of the probe should be greater than the warpage to ensure good contact between the probe and the strain gauge pad. For a board length of 10 mm, that is, 2*2 strain gauges, the probe height is 75 microns, and for a board length of 100 mm, that is, 20*20 strain gauges, the probe height is 0.75 mm. For example, the height range of the probe pair is 5μm to 1mm. Preferably, the probe height can be set to 100μm.

[0036] The embodiment of the present invention also provides a method for batch automatic measurement of strain gauge resistance values, using the device of the above embodiment of the present invention to perform batch automatic measurement of strain gauge resistance values. Specifically, the method includes: Step S11, determine the shape, specification, and strain gauge arrangement mode of the strain gauge array to be measured, and configure a measurement template that matches the strain gauge array to be measured according to the shape, specification, and strain gauge arrangement mode of the strain gauge array.

[0037] Step S12: Assemble the strain gauge array on the measurement template so that the positive pads and negative pads of each strain gauge are connected to the positive and negative probes of the corresponding probe pairs on the measurement template.

[0038] Step S13: Send control signals to the positive multiplexer switch and the negative multiplexer switch through the microcontroller to control the positive multiplexer switch and the negative multiplexer switch to select and connect a single strain gauge on the strain gauge array, so as to obtain the resistance value data of each strain gauge respectively. Specifically, control the positive multiplexer switch and the negative multiplexer switch through the microcontroller to select and connect the probe pairs corresponding to each strain gauge, collect the current measurement results of the current measurer, and calculate the resistance value of the strain gauge according to the current measurement results.

[0039] In this step, the microcontroller is respectively connected to the selection input ports of the positive multiplexer switch and the negative multiplexer switch, and the switches of the corresponding circuits are closed through the instructions of the microcontroller, so as to conduct the measurement circuit of the selected strain gauge. When the measurement circuit of a certain strain gauge is conducted, a current will be generated on this circuit. On the premise of a given voltage, by measuring the current value of each strain gauge, the resistance value of the strain gauge can be calculated according to Ohm's law.

[0040] Exemplarily, the method further includes: Step S21: After obtaining each resistance value, construct a resistance value matrix according to the resistance value data, and analyze the resistance value matrix to determine the abnormal resistance value analysis result. For example, compare the numerical values of the resistance values in the resistance value matrix, and screen out the resistance values with obvious abnormalities. Step S22: Determine the corresponding abnormal strain gauge according to the abnormal resistance value analysis result. Step S23: Store the resistance value analysis result corresponding to the abnormal strain gauge in the database.

[0041] In addition, an intelligent terminal device can be provided and connected to the automatic measurement device. The user can create an automatic measurement task for the resistance strain gauge on the terminal device side, receive the data collected by the automatic measurement device, and analyze and process the data.

[0042] According to the above embodiments of the present invention, the batch automatic measurement device and method for the resistance value of the strain gauge can be applied to a variety of different styles of resistance strain gauges by setting a replaceable measurement template; by arranging probe pairs in an array on the measurement template, the resistance value of the strain gauges in the strain gauge array can be measured by controlling the measurement circuit, so as to realize the batch automatic detection of the resistance value and improve the detection accuracy; and by only using a microcontroller, a measurement circuit and a replaceable measurement template to form the automatic measurement device, the composition of the device is effectively simplified and the cost of the device is reduced.

[0043] Only some exemplary embodiments of the present invention have been described by way of illustration. Without doubt, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An automatic batch measurement device for the resistance value of strain gauges, characterized in that, It includes a measurement template, a measurement circuit, and a microcontroller. The measurement template is used to carry the strain gauge array to be measured and connect the strain gauge array to the measurement circuit. The measurement template includes a first layer and a second layer. On the front of the first layer of the measurement template, there are probe pairs arranged in an array, and the arrangement of the probe pairs matches the arrangement of the strain gauges in the strain gauge array to be measured. The probe pair includes a positive probe and a negative probe, and the positive probe and the negative probe are respectively used to connect to the positive pad and the negative pad of each strain gauge. On the front of the second layer of the measurement template, there is a positive lead, and on the back of the second layer of the measurement template, there is a negative lead. The positive probes are sequentially connected through the positive lead to form a positive probe row, and the negative probes are sequentially connected through the negative lead to form a negative probe column. On the back of the second layer of the measurement template, there are also a positive lead interface and a negative lead interface. Each positive lead is connected to the positive lead interface, and each negative lead is connected to the negative lead interface. The measurement circuit is used to measure the resistance value of the strain gauge. The measurement circuit includes a positive multiplexer switch, a negative multiplexer switch, a current measurer, and a measurement power supply. The input port of the positive multiplexer switch is connected to the positive lead interface, and the output port is connected to the measurement power supply. The input port of the negative multiplexer switch is connected to the negative lead interface, and the output port is connected to the current measurer. The positive multiplexer switch is used to select the positive probe row, and the negative multiplexer switch is used to select the negative probe column. The microcontroller is connected to the positive multiplexer switch, the negative multiplexer switch, and the current measurer, and is used to control the positive multiplexer switch and the negative multiplexer switch to select the probe pairs corresponding to each strain gauge, collect the current measurement result of the current measurer, and calculate the resistance value of the strain gauge according to the current measurement result.

2. The device according to claim 1, characterized in that, Blind holes are respectively arranged on the first layer and the second layer of the measurement template, and through holes penetrating the first layer and the second layer are arranged on the measurement template. The positive probe is connected to the positive lead through the blind hole on the first layer, and the negative probe is connected to the negative lead through the through hole. Each positive lead is connected to the positive lead interface through the blind hole on the second layer.

3. The device according to claim 1 or 2, characterized in that, The measurement template includes multiple styles for matching strain gauge arrays of different specifications and shapes; each probe pair is movably arranged on the measurement template and can be arranged according to the arrangement of the strain gauges in the strain gauge array.

4. The device according to claim 1 or 2, characterized in that, On the front of the first layer of the measurement template, there are also positioning marks, which are used to position each strain gauge in the strain gauge array.

5. The device according to claim 1 or 2, characterized in that, The height of the probe pair is higher than the front of the first layer of the measurement template.

6. The device according to claim 5, characterized in that, The height of the probe pair is 5μm to 1mm.

7. The device according to claim 1 or 2, characterized in that, An operational amplifier is arranged between each positive probe row and the positive multiplexer switch for impedance matching and isolating interference from the measurement voltage.

8. The device according to claim 1 or 2, characterized in that, The positive lead interface and the negative lead interface are pin headers or pads.

9. An automatic batch measurement method for the resistance value of a strain gauge, characterized in that, Using the device according to any one of claims 1 - 8 for batch automatic measurement of the resistance value of a strain gauge, the method includes: Selecting a measurement template that matches according to the shape, specification, and arrangement of the strain gauges in the strain gauge array to be measured. Assemble the strain gauge array to be measured on the measurement template so that the positive pads and negative pads of each strain gauge are connected to the positive probes and negative probes of the corresponding probe pairs on the measurement template; Control the positive multiplexer switch and the negative multiplexer switch through the microcontroller to select the probe pairs corresponding to each strain gauge, collect the current measurement results of the current measurer, and calculate the resistance value of the strain gauge according to the current measurement results.

10. The method according to claim 9, characterized in that, The method further includes: Construct a resistance value matrix based on the resistance value data of each strain gauge, analyze the resistance value matrix, and determine the abnormal resistance value analysis result; Determine the corresponding abnormal strain gauge according to the abnormal resistance value analysis result; Store the resistance value analysis result corresponding to the abnormal strain gauge in the database.

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