A sensitivity calibration device and calibration method for a strain sensor

Abstract

The invention discloses a sensitivity calibration device and a calibration method for a strain sensor. The calibration device comprises: a bottom plate, a guide rail slide, guide rail clamping blocks at both ends of the guide rail slide, a front stopper in front of the guide rail slide, a rear stopper at the rear side of the guide rail slide, a fixed block and an upper slider on the guide rail slide; the fixed block and the upper slider are respectively equipped with structures for fixing the strain sensor, pulley fixing frames are arranged at both ends of the guide rail, a pulley is fixed on the pulley fixing frame, one end of a thin rope is fixed on the upper slider, a weight is hung on the other end of the thin rope passing around the pulley, a side stopper is fixed on the slider, a micrometer fixing frame is fixed on the front stopper, and a micrometer is fixed on the micrometer fixing frame. Calibration by using the device can achieve the following effects: good repeatability of calibration results, reliable results, high-precision calibration, stable, sturdy and durable device, convenient calibration, time-saving, labor-saving, fast and efficient, etc.

Description

Technical Field

[0001] The invention relates to a sensitivity calibration device and a calibration method for a strain sensor. Background Art

[0002] Strain refers to the relative deformation of an object under the influence of external forces and non-uniform temperature fields. In practical applications, strain sensors are usually used to test the strain of an object. Strain sensors are based on measuring the strain generated by the deformation of an object under force. Strain sensors are widely used in structural strain detection of large buildings such as bridges, tunnels, power towers, oil platforms, buildings, steel structures, ships, tower cranes, gantry cranes, etc. However, the sensitivity of each strain sensor is different, and the sensitivity coefficient must be calibrated before use to ensure the accuracy of strain detection.

[0003] At present, most units use isotonic beams to calibrate strain sensors. This method is to install strain and strain sensors on isotonic beams at the same time, apply weights to their free ends to produce tensile deformation approximately along the axial direction, apply different weights in turn, and fit the obtained data to calibrate the strain sensors. However, when using this method to calibrate strain sensors of different gauge lengths, it is necessary to replace isotonic beams, which is extremely inconvenient. Moreover, this method cannot produce completely axial tension because the deformation of its beam arm will amplify the strain. When calibrating strain sensors, due to the strain values ​​between different parts of isotonic beams and the strain values ​​measured by the sensors and the strain values ​​measured by the strain gauges on the isotonic beams, the accuracy requirements for calibrating strain sensors that measure small strains cannot be met. In terms of fixing methods, one isotonic beam can only fix strain sensors of one gauge length. To calibrate strain sensors of multiple gauge lengths, multiple isotonic beams need to be configured, which has poor versatility.

[0004] At present, improvements have been made to this technology both at home and abroad, but the sensor sensitivity coefficient error of the calibration device in China is large, and the efficiency of the calibration work is low, and it is impossible to perform sensor comparison tests. The price abroad is expensive, and it is impossible to calibrate strain sensors with different gauge lengths at the same time, and it is impossible to calibrate and compare multiple strain sensors at the same time. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned technology, the purpose of the present invention is to provide a sensitivity calibration device and calibration method for strain sensors that can calibrate multiple sensors at the same time, calibrate any scale length, have small calibration error and high accuracy.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a sensitivity calibration device for a strain sensor, comprising: a base plate, a guide rail slide, guide rail clamps at both ends of the guide rail slide, a front stopper in front of the guide rail slide, a rear stopper on the rear side of the guide rail slide, a fixed block and an upper slider on the guide rail slide; the fixed block and the upper slider are respectively installed with structures for fixing the strain sensor, pulley fixing frames are provided at both ends of the guide rail, a pulley is fixed on the pulley fixing frame, one end of a thin rope is fixed on the upper slider, and a weight is hung on the other end of the thin rope around the pulley, a side stopper is fixed on the slider, a micrometer fixing frame is fixed on the front stopper, and a micrometer is fixed on the micrometer fixing frame.

[0007] The guide rail slide table is composed of a guide rail and a lower slider which can move axially along the guide rail.

[0008] The fixing block is fixed on the guide rail slider through a screw structure.

[0009] The upper slider is fixed on the lower slider through a screw structure.

[0010] The strain sensor is fixed on the upper slider and the fixed block through M6 flat washers and nuts.

[0011] The structure for fixing the strain sensor is a screw structure.

[0012] The side stopper is fixed on the slide block through a screw rod and is perpendicular to the horizontal plane of the slide block. The micrometer is fixed on the micrometer fixing frame through a screw rod.

[0013] A calibration method using a strain sensor sensitivity calibration device, the calibration method can be calibrated according to the calibration idea of ​​the comparison method in static calibration in the following steps:

[0014] (1) Installation: According to the inventive device, according to the strain sensors of different structures, the standard strain sensor and the strain sensor to be calibrated are connected and installed in the correct position, the micrometer probe is pushed to the side block to measure the initial value, and the weights are hung on the front and rear sides.

[0015] (2) Calibration: After the strain sensor is installed and checked, apply excitation power to the sensor and measure the change in its bridge voltage. The linear relationship between the strain size and the axial force it is subjected to is shown. The coefficient corresponding to the sensor to be tested is obtained by using the known coefficient of the standard strain sensor.

[0016] (3) Verification: Push the micrometer probe to the side block to measure the current value. The difference between the current value and the initial value is the displacement value. The accuracy of the coefficient is verified by the displacement value.

[0017] (4) After the strain sensor is calibrated, stop applying the excitation power, remove the weight, and stop the device from working.

[0018] The bridge voltage measurement in step 2 utilizes the Wheatstone bridge measurement principle.

[0019] The method of verifying the coefficient using the displacement value in step 3 is the formula definition method; the coefficient of the sensor multiplied by the collected voltage will equal the strain, and the displacement measured by the micrometer divided by its own scale length will also equal the strain. The accuracy of the coefficient is verified based on the equations of the two.

[0020] Beneficial effects: After adopting the above scheme, the present invention has the following positive effects and advantages:

[0021] (1) Good repeatability of calibration results: Repeated calibration will result in good consistency and repeatability of the strain sensor sensitivity coefficient, and the results will be reliable.

[0022] (2) Calibration is convenient, time-saving, labor-saving, fast and efficient. It effectively prevents the lateral movement of the device, ensures that the force is applied in the axial direction, and achieves high-precision calibration of the strain sensor.

[0023] (3) It is adaptable to strain sensors with different gauge lengths and can calibrate multiple ones at the same time, with strong versatility and high efficiency.

[0024] (4) Two calibration methods are integrated in one device, which can verify the calibration results. The device is stable, sturdy and durable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is an exploded view of the device of the present invention;

[0026] Figure 2 It is a complete diagram of the device of the present invention;

[0027] In the figure: 1, base plate; 2, guide rail clamp; 3, rear block; 4, fixed block; 5, upper slide block; 6, micrometer fixing frame; 7, front block; 8, lower slide block; 9, guide rail; 10, pulley fixing frame; 11, side block; 12, pulley; 13, weight; 14, thin rope; 15, micrometer. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The present invention discloses a sensitivity calibration device for a strain sensor, such as Figure 2 As shown, the calibration device comprises:

[0030] Bottom plate 1; guide rail slide, the guide rail slide is composed of a guide rail 9 and a lower slider 8 that can move along the axial direction of the guide rail; guide rail clamps 2 at both ends of the guide rail slide; a front stopper 7 in front of the guide rail slide; a rear stopper 3 on the rear side of the guide rail slide; a fixed block 4 and an upper slider 5 on the guide rail slide, the fixed block 4 is fixed to the guide rail slider 2 through a screw structure, the upper slider 5 is fixed to the lower slider 8 through a screw structure, the fixed block 4 and the upper slider 5 are respectively installed with a structure for fixing a strain sensor, the preferred embodiment of the structure is a screw structure, the strain sensor The sensor is fixed to the upper slider 5 and the fixed block 4 by M6 flat washers and nuts; pulley fixing frames 10 are provided at both ends of the guide rail 9, and a pulley 12 is fixed to the pulley fixing frame 10; one end of a thin rope 14 is fixed to the upper slider 5, and a weight 13 is hung on the other end of the thin rope 14 around the pulley; a side block 11 is fixed to the slider 5, and the side block 11 is fixed to the slider 5 by a screw and is perpendicular to the horizontal plane of the slider 5; a micrometer fixing frame 6 is fixed to the front block 7, and a micrometer 15 is fixed to the micrometer fixing frame 6 by screws.

[0031] When using Example 1, one end of the standard strain sensor and the strain sensor to be measured is fixed to the upper slider 5, and the other end is fixed to the fixed block 4, respectively, and fixed with M6 flat washers and nuts, and tightened with a socket wrench. One end of the thin rope 14 is fixed to the upper slider 5, and the other end is passed around the front pulley 12, and a weight 13 is hung at the other end. According to the Wheatstone bridge measurement principle, the change of resistance is used to measure the change of physical quantity, and an excitation power supply is applied to the sensor and its bridge voltage change is measured. According to the linear relationship between the strain size and the size of the axial force it is subjected to, and through the known coefficients of the standard strain sensor, the coefficient corresponding to the sensor to be measured can be obtained, thereby achieving the purpose of calibrating the strain sensor with unknown coefficients. This calibration method can realize sensor calibration, is easy to use, and has high precision.

[0032] When the embodiment 2 is used, the micrometer can be used for calibration alone. The side block 11 is fixed to the slider 5 by a screw rod and is perpendicular to the horizontal plane of the slider 5. The micrometer bracket 6 is fixed to the front block 7 by bolts, and the micrometer is fixed to the micrometer bracket 6 by screws. In the initial state (no weights are hung on the front and rear sides), the micrometer 15 probe is pushed to the side block 11 to measure the initial value. When the weights are hung on the front or rear side, the micrometer 15 probe is pushed to the side block 11 to measure the current value. The displacement value is obtained by subtracting the current value from the initial value. The ratio of the displacement value to the sensor gauge length (the initial length of the sensor) is the microstrain, thereby realizing the calibration of the strain sensor.

[0033] The best embodiment is to combine the above two methods, first measure the coefficient of the sensor to be measured, then measure the displacement, and finally use the formula definition method to verify the calibration result.

[0034] The device can calibrate strain sensors with different gauge lengths and strain sensors with different fixing methods.

[0035] Strain sensors with different gauge lengths can be fixed and calibrated by adjusting the axial distance position of the screw for fixing the strain sensor on the upper slider 5. The axial distance position of the screw for fixing the strain sensor on the upper slider 5 is adjusted, and a screw hole for fixing the screw is opened at a corresponding position of the upper slider 5 according to the gauge length of the strain sensor to be calibrated compared with the gauge length of the standard strain sensor.

[0036] Under the condition of the same displacement, the strain value generated by strain sensors with different gauge lengths is inversely proportional to the gauge length value. The correct strain value of the calibrated sensor can be calculated. This relationship can be used to calculate the sensitivity coefficient of the strain sensor by fitting a series of corresponding relationships.

[0037] By fixing a standard strain sensor between the fixed block 4 and the upper slider 5 and gluing the strain sensor on the fixed block 4 and the upper slider 5 , the strain sensors with different fixing methods and arbitrary gauge lengths can be flexibly calibrated.

[0038] Through the two-standard one installation method, the error caused by the unbalanced displacement of the device can be eliminated: according to the sensitivity calibration device of the strain sensor described in claim 1, there are three installation positions of strain sensors on the left, middle and right on the fixed block 4 and the upper sliding block 5, two standard strain sensors are installed on the left and right positions respectively, and one strain sensor to be measured is installed in the middle position. The standard strain value adopts the average value of the strain values ​​read by the two standard sensors on the left and right, which can eliminate the error caused by the unbalanced displacement of the device.

[0039] A calibration method using a strain sensor sensitivity calibration device, the calibration method can be calibrated according to the calibration idea of ​​the comparison method in static calibration in the following steps:

[0040] (1) Installation: According to the inventive device, according to the strain sensors of different structures, the standard strain sensor and the strain sensor to be calibrated are connected and installed in the correct position, the micrometer probe is pushed to the side block to measure the initial value, and the weights are hung on the front and rear sides.

[0041] (2) Calibration: After the strain sensor is installed and checked, apply excitation power to the sensor and measure the change in its bridge voltage. The linear relationship between the strain size and the axial force it is subjected to is shown. The coefficient corresponding to the sensor to be tested is obtained by using the known coefficient of the standard strain sensor.

[0042] (3) Verification: Push the micrometer probe to the side block to measure the current value. The difference between the current value and the initial value is the displacement value. The accuracy of the coefficient is verified by the displacement value.

[0043] (4) After the strain sensor is calibrated, stop applying the excitation power, remove the weight, and stop the device from working.

[0044] In addition, the bridge voltage measurement in step 2 utilizes the Wheatstone bridge measurement principle.

[0045] In addition, the method of verifying the coefficient using the displacement value in step 3 is the formula definition method; the coefficient of the sensor multiplied by the collected voltage will equal the strain, and the displacement measured by the micrometer divided by its own scale length will also equal the strain. The accuracy of the coefficient is verified based on the equations of the two.

[0046] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any changes or modifications made according to the claims and description of the present invention should fall within the scope of the patent of the present invention.

Claims

1. A calibration method for a sensitivity calibration device of a strain sensor, characterized in that The calibration device comprises: a base plate (1), a guide rail slide, guide rail clamps (2) at both ends of the guide rail slide, a front stopper (7) in front of the guide rail slide, a rear stopper (3) at the rear side of the guide rail slide, a fixed block (4) and an upper slider (5) on the guide rail slide, wherein the fixed block (4) and the upper slider (5) are respectively provided with structures for fixing strain sensors, pulley fixing frames (10) are provided at both ends of the guide rail (9), a pulley (12) is fixed on the pulley fixing frame (10), one end of a thin rope (14) is fixed on the upper slider (5), and a weight (13) is hung on the other end of the thin rope (14) passing around the pulley, a side stopper (11) is fixed on the upper slider (5), a micrometer fixing frame (6) is fixed on the front stopper (7), and a micrometer (15) is fixed on the micrometer fixing frame; According to the calibration idea of ​​the comparison method in static calibration, the calibration can be carried out in the following steps: (1) According to the inventive device, based on the strain sensors with different structures, the standard strain sensor and the strain sensor to be calibrated are connected and installed in the correct position, weights are hung on the front and rear sides, and the micrometer probe is pushed against the side block to measure the initial value. (2) There are three installation positions of strain sensors on the fixed block (4) and the upper slider (5), namely, left, middle and right. Two standard strain sensors are installed on the left and right positions respectively, and one strain sensor to be measured is installed in the middle position. This can eliminate the error caused by the unbalanced displacement of the device. (3) After the strain sensor is installed and checked, apply excitation power to the sensor and measure the change in its bridge voltage. The strain size is linearly related to the axial force it is subjected to. The coefficient corresponding to the sensor to be tested is obtained by using the known coefficient of the standard strain sensor. (4) Push the micrometer probe to the side block to measure the current value. The difference between the current value and the initial value is the displacement value. The accuracy of the coefficient is verified by the displacement value. (5) After the strain sensor calibration is completed, stop applying the excitation power, remove the weight, and stop the device from working.

2. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The guide rail slide is composed of a guide rail (9) and a lower slider (8) which can move axially along the guide rail.

3. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The fixing block (4) is fixed to the guide rail clamping blocks (2) at both ends of the guide rail slide via a screw structure.

4. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The upper slider (5) is fixed on the lower slider (8) via a screw structure.

5. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The strain sensor is fixed on the upper slider (5) and the fixed block (4) via an M6 flat washer and a nut.

6. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The structure for fixing the strain sensor is a screw structure.

7. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The axial distance position of the screw for fixing the strain sensor on the upper slider (5) can be adjusted to fix strain sensors with different gauge lengths and perform calibration. The axial distance position of the screw for fixing the strain sensor on the upper slider (5) is adjusted, and a screw hole for fixing the screw is opened at a corresponding position of the upper slider (5) according to the comparison between the gauge length of the strain sensor to be calibrated and the gauge length of the standard strain sensor.

8. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that By fixing a standard strain sensor between a fixed block (4) and an upper slider (5), and gluing the strain sensor on the fixed block (4) and the upper slider (5), the effect of flexibly calibrating strain sensors with different fixing methods and arbitrary gauge lengths can be achieved.

9. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The side block (11) is fixed to the upper slider (5) by a screw rod and is perpendicular to the horizontal plane of the upper slider (5). The micrometer (15) is fixed to the micrometer fixing frame (6) by screws. The micrometer fixing frame (6) is clamped and fixed to the front block without using screws.

10. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The bridge voltage measurement in step 2 utilizes the Wheatstone bridge measurement principle.

11. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The method of verifying the coefficient using the displacement value in step 3 is the formula definition method. The coefficient of the sensor multiplied by the collected voltage is equal to the strain, and the displacement measured by the micrometer divided by its own scale length is also equal to the strain. The accuracy of the coefficient is verified based on the equations of the two.

12. The calibration method of the sensitivity calibration device of the strain sensor according to claim 1, characterized in that The error caused by unbalanced displacement of the device can be eliminated by using the two-standard-one installation method: there are three installation positions of strain sensors on the left, middle and right positions on the fixed block (4) and the upper sliding block (5), two standard strain sensors are installed on the left and right positions respectively, and one strain sensor to be measured is installed in the middle position, and the standard strain value adopts the average value of the strain values ​​read by the two standard sensors on the left and right, which can eliminate the error caused by unbalanced displacement of the device.

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