Dynamic calibration method for force sensor through sine method

Abstract

The invention discloses a dynamic calibration method for a force sensor by a sine method, and the method comprises the following specific steps: 1, placing a force sensor to be detected on a vibration table, arranging a mass block on the force sensor, enabling the vibration table, the force sensor and the mass block to form a test assembly, and building a finite element simulation model; 2, selecting a measurement point position on the surface of the upper end of the mass block; step 3, testing the test assembly through the test bench; 4, analyzing according to the finite element simulation model to obtain acceleration theoretical data of a non-central measurement point on the mass block, and comparing and analyzing the acceleration theoretical data and the acceleration actual measurement data; and if the acceleration theoretical data is matched with the acceleration actual measurement data, acquiring acceleration distribution data of the whole mass block through a finite element simulation model. According to the method, global acceleration distribution of the mass block can be provided through the credible finite element simulation model, and the problem that standard force values are not uniform due to algorithm simplification is fundamentally solved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor calibration, and in particular to a dynamic calibration method for a sinusoidal force sensor. Background Art

[0002] Absolute sinusoidal force calibration device is used to calibrate the dynamic characteristics of force sensors. It mainly consists of a standard vibration table, sensor, mass block, and laser vibrometer to form a calibration system (see attached). Figure 6 (as shown). A standard vibration table applies a sinusoidal force at a specific frequency. The lower end of the force sensor is mounted on the vibration table via a lower connector. The upper end of the upper force sensor is connected to the mass block via an upper connector, acting in conjunction with the standard vibration table. The laser vibrometer's lens emits a laser at the center point of the mass block's upper surface to measure the acceleration of the mass block's upper center point while the entire system is in motion. The dynamic force acting on the force sensor at the specific frequency is then calculated using a corresponding compensation algorithm. This force value serves as the standard force for the calibration system and is compared with the force measured by the force sensor. Calibration is then performed according to the corresponding specifications.

[0003] Existing technology uses only a laser vibrometer to measure the acceleration at the center of the mass's upper surface, and then uses a compensation algorithm to infer the acceleration distribution of the entire mass. Existing academic research on compensation algorithms has all been based on simplified calibration system models, and different research institutions have developed different simplified compensation algorithms.

[0004] For example: Standard force values ​​of the German Federal Institute of Physics and Technology (PTB) F s The algorithm is as follows: ; The standard force value of Beijing Great Wall Metrology and Testing Institute (CIMM) F s The algorithm is as follows: ; Standard force values ​​obtained using different algorithms F s The system model must be different. To achieve consistent results, the system model cannot be arbitrarily simplified (different simplification methods will lead to different calculation results). The actual working conditions of the calibration system must be used as the basis as possible. Traditional theoretical modeling methods will lead to overly complex calculation equations, greatly increasing the amount of calculation and even making the solution difficult. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies in the prior art and to provide a dynamic calibration method for a sinusoidal mana sensor.

[0006] The object of the present invention is achieved through the following technical solution: a dynamic calibration method for a sinusoidal force sensor, comprising the following specific steps: Step 1: Place the force sensor to be tested on a vibration table, set a mass block on the force sensor, and establish a finite element simulation model including the force sensor and the mass block. Step 2: Select several measuring points on the upper surface of the mass block; one of the measuring points is located at the center of the mass block, which is the central measuring point, and the rest are non-central measuring points; Step 3: Testing the test assembly using a test bench equipped with laser vibrometers corresponding to the measurement points. Turning on the vibration table and applying a sinusoidal load to the force sensor and mass block until the acceleration value at the central measurement point reaches a preset value. Simultaneously, measured acceleration data for non-central measurement points is obtained. Step 4: Obtain theoretical acceleration data for non-central measurement points on the mass block based on the finite element simulation model analysis, and compare and analyze the theoretical acceleration data with the measured acceleration data. If the theoretical acceleration data matches the measured acceleration data, obtain the acceleration distribution data of the entire mass block through the finite element simulation model. If the theoretical acceleration data does not match the measured acceleration data, adjust the finite element simulation model and repeat steps 2 to 4.

[0007] Preferably, there are five measuring points in total, two of which are located at one-third of the radius of the upper end surface of the mass block, and two of which are located at two-thirds of the radius of the upper end surface of the mass block.

[0008] Preferably, in step 1, a finite element simulation model is established using Ansys workbench simulation software, and the specific method is as follows: S1: Build a three-dimensional model of the force sensor and mass block, and import the three-dimensional model into the simulation software; S2: Set the elastic modulus, Poisson's ratio, and density of the mass block and force sensor; S3: Mesh the three-dimensional model; S4: Perform modal analysis and obtain multi-order modes, which are then imported into the harmonic response analysis settings of the simulation software to obtain the steady-state response of any point in the three-dimensional model under the action of a sinusoidal load.

[0009] Preferably, in step S2, when determining the elastic modulus and Poisson's ratio of the force sensor, initial values ​​of the elastic modulus and Poisson's ratio of the force sensor are first selected, and then a modal analysis is performed on the overall structure composed of the force sensor and the mass block to obtain the natural frequency of the overall structure; then, an actual vibration test is performed on the overall structure composed of the force sensor and the mass block to obtain a relative amplitude curve within the test vibration frequency range; If the frequency corresponding to the highest point of the relative amplitude curve is consistent with the natural frequency obtained through modal analysis, the current initial values ​​of the elastic modulus and Poisson's ratio are used as the actual elastic modulus and Poisson's ratio of the force sensor; if the frequency corresponding to the highest point of the relative amplitude curve is inconsistent with the natural frequency obtained through modal analysis, the initial values ​​of the elastic modulus and Poisson's ratio are readjusted and the above process is repeated.

[0010] Preferably, in step three, before turning on the vibration table, the gain of the vibration table's power amplifier is first adjusted to the minimum, and then the power supply is turned on; the gain of the vibration table's power amplifier is adjusted so that the acceleration value at the center measurement point reaches a preset value; after the laser vibrometer is stable, the acceleration value of each measurement point is collected by the laser vibrometer; the collection time for each measurement is not less than 10 vibration cycles, and the measurement is repeated multiple times in the same state, and the average value of the multiple measurements is used as the actual measured acceleration data.

[0011] Preferably, in step four, when the theoretical acceleration data does not match the measured acceleration data and the difference between the theoretical acceleration data and the measured acceleration data is less than a set threshold, the parameters of the mass block and the force sensor in the finite element simulation model are adjusted, and the adjustment parameters include Poisson's ratio and elastic modulus; when the theoretical acceleration data does not match the measured acceleration data and the difference between the theoretical acceleration data and the measured acceleration data is greater than a set threshold, the finite element simulation model in step one is re-established, and a vibration table part is added to the finite element simulation model.

[0012] Preferably, the test bench includes a frame, on which a reflector frame, several side laser vibrometers, and a top laser vibrometer are provided. The vibration table on the test assembly is separated from the frame, and the reflector frame is provided with reflectors corresponding one-to-one to the side laser vibrometers. Through the reflectors, a laser round-trip optical path is formed between the side laser vibrometers and non-center measurement points on the mass block; and a laser round-trip optical path is formed between the top laser vibrometer and the center measurement point on the mass block.

[0013] Preferably, the frame is provided with a counterweight for adjusting the natural frequency of the frame, and the bottom of the frame is provided with a shock absorbing device.

[0014] Preferably, the frame is provided with a height adjustment seat, which is adjustably set on the column of the frame, and the height adjustment seat is provided with a horizontal angle adjustment mechanism, and the horizontal angle adjustment mechanism includes a rotating base installed on the height adjustment seat, the rotating base is rotatably set on the height adjustment seat, and the side laser vibrometer is set on the rotating base; a protrusion is provided on the side of the rotating base, and an adjustment seat is provided on the height adjustment seat, and a threaded pusher and an elastic push rod are provided on the adjustment seat, and the threaded pusher and the elastic push rod respectively support the two sides of the protrusion.

[0015] Preferably, a quadrangular pyramid is provided on the reflector frame, and reflectors are provided on the four sides of the quadrangular pyramid; a through hole is provided in the center of the quadrangular pyramid, and the through hole is located directly above the center of the mass block; the through hole is used to allow the laser beam of the top laser vibrometer to pass through.

[0016] The beneficial effects of the present invention are: 1. In the present invention, the test bench has the capability of local multi-point detection. By setting multiple measurement points (central measurement point + non-central measurement point) on the mass block and using multiple laser vibrometers on the test bench for synchronous measurement, the acceleration values ​​at different points on the mass block are obtained. The measured acceleration data at different points are compared and analyzed with the theoretical data obtained from the finite element simulation model, thereby verifying the accuracy of the finite element simulation model and correcting it. The simultaneous measurement of multiple points can obtain acceleration data at different positions on the mass block, so that the verification of the finite element simulation model no longer relies on the data of a single central point, but is based on the comparison of multi-point measured data, which greatly improves the pertinence and accuracy of the model correction.

[0017] 2. The present invention can provide the acceleration distribution of the entire mass block through a reliable finite element simulation model, rather than just the center point data. This allows the calculation of the standard force value to be based on more complete physical field information, improving the accuracy and reliability of force value estimation. In addition, the present invention directly verifies and corrects the finite element model through actual multi-point acceleration measurement, without relying on a specific compensation algorithm, fundamentally solving the problem of inconsistent standard force values ​​caused by algorithm simplification.

[0018] 3. The traditional method of relying on theoretical derivation and compensation algorithm correction is difficult to solve due to the complexity of the equations. However, the present invention uses finite element simulation combined with experimental data correction to avoid complex theoretical derivation while ensuring the authenticity of the model; the efficient computing power of finite element software makes large-scale model analysis possible, achieving a balance between computing efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of the test bench of the present invention.

[0020] Figure 2Schematic diagram of the structure of the reflector frame.

[0021] Figure 3 This is a schematic diagram of the local structure of the laser vibrometer on the side of the test bench.

[0022] Figure 4 Schematic diagram of the distribution of measurement points on the upper surface of the mass block in the present invention.

[0023] Figure 5 A schematic diagram of meshing a three-dimensional model.

[0024] Figure 6 Schematic diagram of a calibration system consisting of a standard vibration table, a sensor, a mass block, and a laser vibrometer in the prior art.

[0025] In the figure: 1. frame, 2. mounting platform, 3. reflector frame, 4. vibration table, 5. force sensor, 6. mass block, 7. side laser vibrometer, 8. top laser vibrometer, 9. counterweight, 10. level, 11. top movable part, 12. shock absorber, 13. quadrangular pyramid, 14. reflector, 15. through hole, 16. height adjustment seat, 17. rotating base, 18. positioning part, 19. elastic top pressure column, 20. adjustment seat, 21. threaded pusher, 22. elastic push rod, 23. bump. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention are within the scope of protection of the present invention.

[0027] It should be understood by those skilled in the art that, in the disclosure of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0028] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the elements may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0029] The present invention discloses a dynamic calibration method for a sinusoidal mana sensor 5, comprising the following specific steps: Step 1: Place the force sensor 5 to be tested on the vibration table 4, set the mass block 6 on the force sensor 5, the vibration table 4, the force sensor 5 and the mass block 6 constitute a test assembly, and establish a finite element simulation model including the force sensor 5 and the mass block 6.

[0030] Step 2: Select several measuring points on the upper surface of the mass block 6; one of the measuring points is located at the center of the mass block 6, which is the central measuring point, and the rest are non-central measuring points.

[0031] Step 3: Test the test assembly using a test bench equipped with laser vibrometers corresponding to the measurement points. Turn on the vibration table 4 and apply a sinusoidal load to the force sensor 5 and the mass block 6, so that the acceleration value of the central measurement point reaches a preset value. At the same time, obtain the actual acceleration data of the non-central measurement points.

[0032] Step 4: Obtain theoretical acceleration data of non-central measurement points on mass block 6 based on finite element simulation model analysis, and compare and analyze the theoretical acceleration data with the measured acceleration data; if the theoretical acceleration data is consistent with the measured acceleration data, obtain the acceleration distribution data of the entire mass block 6 through the finite element simulation model; if the theoretical acceleration data is inconsistent with the measured acceleration data, adjust the finite element simulation model and repeat steps 2 to 4.

[0033] In step 4, if the theoretical acceleration data matches the measured acceleration data, the finite element simulation model has been verified and its accuracy meets the requirements. Once the finite element simulation model has been verified, the acceleration value at any position can be obtained through the finite element simulation model. The acceleration response curve of the acceleration at any desired position in the mass block 6 and the force sensor 5 under the action of a sinusoidal load is obtained through the harmonic response analysis operation process of the finite element simulation model. This result can be regarded as the standard acceleration result experienced by the sensor. By multiplying the standard acceleration result by the mass experienced by the sensor, a standard force value curve can be obtained. The standard force value curve can be used to calibrate the force sensor 5.

[0034] In the present invention, the ability of local multi-point detection of the test bench is achieved by setting multiple measurement points (center measurement point + non-center measurement point) on the mass block 6, and using multiple laser vibrometers on the test bench for synchronous measurement to obtain the acceleration values ​​of different points on the mass block 6. The measured acceleration data of different points are compared and analyzed with the theoretical data obtained by the finite element simulation model, so as to verify the accuracy of the finite element simulation model and correct it. The simultaneous measurement of multiple points can obtain acceleration data at different positions on the mass block 6, so that the verification of the finite element simulation model no longer relies on a single center point data, but is based on comparison of multi-point measured data, which greatly improves the pertinence and accuracy of the model correction.

[0035] Once the finite element simulation model is verified, the credible finite element simulation model can provide the acceleration distribution of the entire mass block 6, rather than just the center point data; this allows the calculation of the standard force value to be based on more complete physical field information, improving the accuracy and reliability of the force value calculation. The traditional calculation method is to use a compensation algorithm that simplifies the model to calculate the acceleration data of different positions. This compensation algorithm has a large error. In addition, the existing technology relies on a simplified compensation algorithm to calculate the standard force value, and different algorithms lead to differences in the calculation results (i.e., the calculation method is not unified); the present invention directly verifies and corrects the finite element model by measuring multi-point acceleration, without relying on a specific compensation algorithm, fundamentally solving the problem of inconsistent standard force values ​​caused by algorithm simplification.

[0036] The traditional method relies on theoretical derivation and compensation algorithm correction, which is difficult to solve due to the complexity of the equations. However, the present invention uses finite element simulation combined with experimental data correction to avoid complex theoretical derivation while ensuring the authenticity of the model; the efficient computing power of finite element software makes large-scale model analysis possible, achieving a balance between computing efficiency and accuracy.

[0037] The present invention adopts the technical route of multi-point measurement + finite element model verification and iterative correction, which effectively solves the problems of inconsistent standard force values ​​and complex calculations in traditional sinusoidal force calibration, significantly improves the accuracy, reliability and repeatability of the dynamic calibration of the force sensor 5, and has important engineering application value and technological innovation significance.

[0038] like Figure 4 As shown, in this embodiment, there are five measuring points in total, two of which are located at one-third of the radius of the upper end surface of the mass block 6, and two of which are located at two-thirds of the radius of the upper end surface of the mass block 6.

[0039] Specifically, in step 1, a finite element simulation model is established using Ansys workbench simulation software. The specific method is as follows: S1: Create a three-dimensional model of the force sensor 5 and the mass block 6, and import the three-dimensional model into the simulation software.

[0040] S2: Set the elastic modulus, Poisson's ratio, and density of the mass block 6 and the force sensor 5 .

[0041] S3: Divide the 3D model into grids; when dividing the 3D model into grids, please refer to the attached Figure 5 Attached Figure 5 In the figure, the larger cylinder is the mass block 6, and the smaller cylinder is the force sensor 5.

[0042] S4: Perform modal analysis and obtain multi-order modes, which are then imported into the harmonic response analysis settings of the simulation software to obtain the steady-state response of any point in the three-dimensional model under the action of a sinusoidal load.

[0043] Among them, in step S2, when determining the elastic modulus and Poisson's ratio of the force sensor 5, the initial values ​​of the elastic modulus and Poisson's ratio of the force sensor 5 are first selected, and then the overall structure composed of the force sensor 5 and the mass block 6 is subjected to a modal analysis to obtain the natural frequency of the overall structure; then, an actual vibration test is performed on the overall structure composed of the force sensor 5 and the mass block 6 to obtain a relative amplitude curve within the test vibration frequency range; if the frequency corresponding to the highest point of the relative amplitude curve is consistent with the natural frequency obtained through the modal analysis, the current initial values ​​of the elastic modulus and Poisson's ratio are used as the actual elastic modulus and Poisson's ratio of the force sensor 5; if the frequency corresponding to the highest point of the relative amplitude curve is inconsistent with the natural frequency obtained through the modal analysis, the initial values ​​of the elastic modulus and Poisson's ratio are readjusted, and the above process is repeated.

[0044] Since the mass block 6 is made of a single material, the density, elastic modulus, Poisson's ratio and other parameters of the mass block 6 are all known. However, since the force sensor 5 has a complex structure and is not made of a single material, its density can be calculated by measuring its mass and volume, but the parameters of the elastic modulus and Poisson's ratio are difficult to obtain directly. In the present invention, the elastic modulus and Poisson's ratio of the sensor are determined by the equivalent method. When selecting the initial value of the elastic modulus and the initial value of the Poisson's ratio of the force sensor 5, a numerical value can be preliminarily assumed based on the material of the sensor. For example, if the force sensor 5 is made entirely of steel, the elastic modulus can be 210GPa and the Poisson's ratio can be 0.3. By repeatedly adjusting the parameters and comparing the frequency curves, the dynamic response of the finite element model is highly consistent with the actual system. After 3-5 iterations, the frequency matching error can be controlled within 1%.

[0045] Traditional methods require testing the elastic modulus and Poisson's ratio of each component of the force sensor 5 separately, but complex structures (such as multi-material stacks and internal strain beams) are difficult to separate and measure. The present invention infers parameters by inferring the overall system's dynamic response, eliminating the need to disassemble the sensor and directly obtaining equivalent material parameters. This approach is applicable to force sensors 5 of any structural form. By using an innovative method of inferring material parameters based on system-level dynamic response, the present invention solves the problem of directly measuring the elastic modulus and Poisson's ratio of complex force sensors 5, significantly improving the accuracy and calibration efficiency of finite element models and providing key technical support for high-precision dynamic force measurement.

[0046] In step three, before turning on vibration table 4, the gain of its power amplifier is set to minimum, and then its power is turned on. The gain of the power amplifier of vibration table 4 is also adjusted so that the acceleration value at the central measurement point reaches the preset value. After the laser vibrometer is stable, the acceleration value at each measurement point is collected using the laser vibrometer. Each measurement is collected for no less than 10 vibration cycles. Repeat the measurement multiple times in the same state, and the average of these multiple measurements is used as the actual acceleration data.

[0047] Furthermore, in step four, when the theoretical acceleration data does not match the measured acceleration data and the difference between the theoretical acceleration data and the measured acceleration data is less than the set threshold, the parameters of the mass block 6 and the force sensor 5 in the finite element simulation model are adjusted, and the adjustment parameters include Poisson's ratio and elastic modulus; when the theoretical acceleration data does not match the measured acceleration data and the difference between the theoretical acceleration data and the measured acceleration data is greater than the set threshold, the finite element simulation model in step one is re-established, and the vibration table 4 part is added to the finite element simulation model.

[0048] In the present invention, when the acceleration theoretical data and the acceleration measured data do not match, the means of parameter correction or model reconstruction are adopted. When the difference is less than the set threshold, that is, the difference between the acceleration theoretical data and the measured data is small (does not exceed the threshold), it shows that the structural framework of the finite element simulation model is reasonable, but the model parameters (such as elastic modulus, Poisson's ratio) have a certain deviation from the actual. At this time, by adjusting these parameters, the dynamic characteristics such as stiffness and damping of the structure in the model can be directly corrected, so that the simulation results are closer to the actual vibration response. In this way, there is no need to rebuild the overall model, only iterative optimization is performed on the material parameters, which reduces the amount of calculation and debugging time, is suitable for subtle errors caused by material parameter deviations, and improves simulation efficiency.

[0049] However, when the difference exceeds the threshold, the surface model may have systematic errors, ignoring the influence of key physical components (such as vibration table 4) on the simulation results, resulting in inaccurate simulation of the excitation transmission path or boundary conditions; at this time, by reconstructing and improving the finite element simulation model and adding the vibration table 4 part, the model can fully consider the dynamic characteristics of the excitation source (such as mass, stiffness, and vibration transmission mode), avoiding data deviations caused by simplified models, and fundamentally solving the systematic errors of the finite element simulation model.

[0050] This phased optimization strategy for the finite element simulation model, implemented in this paper, uses thresholds to distinguish error types. Small errors are addressed by focusing on adjusting model parameters, while large errors are addressed by reconstructing the model structure. This avoids a one-size-fits-all approach to model modification and minimizes ineffective calculations while ensuring model accuracy. Directly reconstructing the finite element simulation model for deviations less than a set threshold significantly increases workload and wastes computing resources. Simply adjusting parameters for large errors fails to address the systematic errors in the finite element simulation model.

[0051] The parameters (elastic modulus, Poisson's ratio, etc.) of the vibration table 4 are determined in the same manner as the force sensor 5 .

[0052] like Figure 1 As shown, the test bench includes a frame 1, on which are provided a reflector frame 3, several side laser vibrometers 7, and a top laser vibrometer 8. The vibration table 4 on the test assembly is separated from the frame 1. The reflector frame 3 is provided with reflectors 14 corresponding one-to-one to the side laser vibrometers 7. Through the reflectors 14, a laser round-trip optical path is formed between the side laser vibrometers 7 and non-central measurement points on the mass block 6; and a laser round-trip optical path is formed between the top laser vibrometer 8 and the central measurement point on the mass block 6.

[0053] The frame 1 is constructed from alloy profiles and includes four columns. A mounting platform 2 is mounted on the frame 1, and a reflector frame 3 is mounted on the mounting platform 2. A level 10 is installed on the mounting platform 2 to check the horizontality of the mounting platform 2. The test assembly is placed directly below the reflector frame 3. A reflector 14 on the reflector frame 3 is positioned at a 45-degree angle. The laser beam emitted by the side laser vibrometer 7 is reflected by the reflector 14 and directed toward the measurement point on the upper surface of the mass block 6. After reflecting off the mass block 6, the laser beam returns to the side laser vibrometer 7 along the same path. The laser beam emitted by the top laser vibrometer 8 directly hits the center of the upper end face of the mass block 6 from the top, reflects off the mass block 6, and returns to the top laser vibrometer 8 along the same path.

[0054] Given the large size of currently available laser vibrometers and the relatively small mass 6 in a small-range sinusoidal force standard device (for example, with a force measurement range of 10N-250N), placing two or more laser vibrometers side by side and inverted vertically would result in the large distance between their lenses, preventing the projected laser beams from completely landing on the upper surface of mass 6. The test bench of the present invention effectively addresses this problem. The test bench uses multiple reflectors 14 to redirect the laser beams, ensuring that the laser beams emitted by each lateral laser vibrometer 7 accurately strike the measurement points on the upper surface of mass 6, thereby meeting the test and calibration requirements of force sensor 5.

[0055] The frame 1 is provided with a counterweight 9 for adjusting the natural frequency of the frame 1, and a shock-absorbing device 12 is provided at the bottom of the frame 1. Although the vibration table 4 is separated from the frame 1, during the operation of the vibration table 4, its vibration may be transmitted to the frame 1 through the ground or the base, thereby adversely affecting the accuracy of the measurement. In the present invention, by adding a counterweight 9 to the frame 1, the counterweight 9 can increase the overall weight and natural frequency of the frame 1, and improve the stability of the frame 1, and reduce the vibration effect of the vibration table 4 on the frame 1. A shock-absorbing device 12 is provided at the bottom of the frame 1, and the shock-absorbing device 12 can have a good vibration isolation effect on the frame 1. The shock-absorbing device 12 can further reduce the influence of external vibration on the frame 1, thereby ensuring the reliability of the test results.

[0056] like Figure 2 As shown, a quadrangular pyramid 13 is provided on the reflector frame 3, and reflectors 14 are provided on the four sides of the quadrangular pyramid 13; a through hole 15 is provided at the center of the quadrangular pyramid 13, and the through hole 15 is located directly above the center of the mass block 6; the through hole 15 is used to allow the laser beam of the top laser vibrometer 8 to pass through.

[0057] like Figure 3 As shown, the frame 1 is provided with a height adjustment seat 16, which is adjustably set on the column of the frame 1, and the height adjustment seat 16 is provided with a horizontal angle adjustment mechanism, which includes a rotating base 17 installed on the height adjustment seat 16, and the rotating base 17 is rotatably set on the height adjustment seat 16, and the side laser vibrometer 7 is set on the rotating base 17; a protrusion 23 is provided on the side of the rotating base 17, and an adjustment seat 20 is provided on the height adjustment seat 16, and a threaded pusher 21 and an elastic push rod 22 are provided on the adjustment seat 20, and the threaded pusher 21 and the elastic push rod 22 respectively support the two sides of the protrusion 23.

[0058] The height adjustment base 16 is used to adjust the height of the side laser vibrometer 7, while the rotating base 17 is used to adjust the horizontal direction of the side laser vibrometer 7. By precisely adjusting the height and horizontal direction of the side laser vibrometer 7, the laser light emitted by the side laser vibrometer 7 can accurately land on the measurement point on the mass 6. When the rotating base 17 is stationary, the elastic push rod 22 applies elastic pressure to the protrusion 23 toward the threaded pusher 21, thereby tightening the protrusion 23 between the elastic push rod 22 and the threaded pusher 21. When the horizontal direction of the side laser vibrometer 7 needs to be adjusted, the threaded pusher 21 is rotated to push the protrusion 23, which in turn rotates the rotating base 17, thereby adjusting the horizontal direction of the side laser vibrometer 7.

[0059] Among them, the rotating base 17 is cylindrical, and a positioning piece 18 and an elastic pressing column 19 are provided on the height adjustment seat 16. The positioning piece 18 and the elastic pressing column 19 are respectively located on both sides of the rotating base 17. The positioning piece 18 is provided with an arc positioning surface that matches the side surface of the rotating base 17, and the side surface of the rotating base 17 contacts the arc positioning surface; the elastic pressing column 19 applies elastic pressure to the side surface of the rotating base 17, and the elastic pressure is directed toward the positioning piece 18. Under the action of this elastic pressure, the rotating base 17 can stably rest against the arc positioning surface of the positioning piece 18.

[0060] A guide rail is installed at the top of the frame 1, on which a top movable member 11 is adjustable. The top laser vibrometer is mounted on this movable member 11. The movable member 11 can slide along the guide rail to adjust the position of the top laser vibrometer, ensuring that the top laser vibrometer can be accurately aligned with the measurement point.

[0061] The laser vibrometer of this invention utilizes the laser Doppler principle. When laser light strikes the surface of a moving object, the reflected light's frequency changes due to the object's motion. This frequency change is proportional to the object's velocity. By measuring the frequency difference between the reflected and incident light, the object's vibration velocity can be calculated, and further parameters such as the vibration amplitude and acceleration can be derived.

[0062] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A dynamic calibration method for a sinusoidal force sensor, characterized in that: The specific steps include: Step 1: Place the force sensor to be tested on a vibration table, set a mass block on the force sensor, and establish a finite element simulation model including the force sensor and the mass block. Step 2: Select several measuring points on the upper surface of the mass block; one of the measuring points is located at the center of the mass block, which is the central measuring point, and the rest are non-central measuring points; Step 3: Testing the test assembly using a test bench equipped with laser vibrometers corresponding to the measurement points. Turning on the vibration table and applying a sinusoidal load to the force sensor and mass block until the acceleration value at the central measurement point reaches a preset value. Simultaneously, measured acceleration data for non-central measurement points is obtained. Step 4: Obtain theoretical acceleration data for non-central measurement points on the mass block based on the finite element simulation model analysis, and compare and analyze the theoretical acceleration data with the measured acceleration data. If the theoretical acceleration data matches the measured acceleration data, obtain the acceleration distribution data of the entire mass block through the finite element simulation model. If the theoretical acceleration data does not match the measured acceleration data, adjust the finite element simulation model and repeat steps 2 to 4.

2. A dynamic calibration method for a sinusoidal force sensor according to claim 1, characterized in that: There are five measuring points in total, two of which are located at one-third of the radius of the upper end surface of the mass block, and two of which are located at two-thirds of the radius of the upper end surface of the mass block.

3. The dynamic calibration method of a sinusoidal force sensor according to claim 1, characterized in that: In step 1, a finite element simulation model is established using Ansys workbench simulation software. The specific method is as follows: S1: Build a three-dimensional model of the force sensor and mass block, and import the three-dimensional model into the simulation software; S2: Set the elastic modulus, Poisson's ratio, and density of the mass block and force sensor; S3: Mesh the three-dimensional model; S4: Perform modal analysis and obtain multi-order modes, which are then imported into the harmonic response analysis settings of the simulation software to obtain the steady-state response of any point in the three-dimensional model under the action of a sinusoidal load.

4. A dynamic calibration method for a sinusoidal force sensor according to claim 3, characterized in that: In step S2, when determining the elastic modulus and Poisson's ratio of the force sensor, initial values ​​of the elastic modulus and Poisson's ratio of the force sensor are first selected, and then a modal analysis is performed on the overall structure composed of the force sensor and the mass block to obtain the natural frequency of the overall structure; then, an actual vibration test is performed on the overall structure composed of the force sensor and the mass block to obtain a relative amplitude curve within the test vibration frequency range; If the frequency corresponding to the highest point of the relative amplitude curve is consistent with the natural frequency obtained through modal analysis, the current initial values ​​of elastic modulus and Poisson's ratio are used as the actual elastic modulus and Poisson's ratio of the force sensor; If the frequency corresponding to the highest point of the relative amplitude curve is inconsistent with the natural frequency obtained through modal analysis, the initial values ​​of the elastic modulus and Poisson's ratio are readjusted and the above process is repeated.

5. The dynamic calibration method of a sinusoidal force sensor according to claim 1, characterized in that: In step three, before turning on the vibration table, adjust the gain of the vibration table's power amplifier to the minimum and then turn on its power. Adjust the gain of the vibration table's power amplifier so that the acceleration value at the center measurement point reaches the preset value. After the laser vibrometer stabilizes, use the laser vibrometer to collect acceleration values ​​at each measurement point. Each measurement should be collected for at least 10 vibration cycles. Repeat the measurement multiple times in the same state, and use the average of these multiple measurements as the actual acceleration data.

6. The method for dynamic calibration of a sinusoidal force sensor according to claim 1, wherein: In step four, when the theoretical acceleration data does not match the measured acceleration data and the difference between the theoretical acceleration data and the measured acceleration data is less than the set threshold, the parameters of the mass block and the force sensor in the finite element simulation model are adjusted, and the adjustment parameters include Poisson's ratio and elastic modulus; when the theoretical acceleration data does not match the measured acceleration data and the difference between the theoretical acceleration data and the measured acceleration data is greater than the set threshold, the finite element simulation model in step one is re-established, and the vibration table part is added to the finite element simulation model.

7. The dynamic calibration method of a sinusoidal force sensor according to claim 1, characterized in that: The test bench includes a frame, on which are provided a reflector frame, several side laser vibrometers, and a top laser vibrometer. The vibration table on the test assembly is separated from the frame. The reflector frame is provided with reflectors corresponding one-to-one to the side laser vibrometers. The reflectors form a round-trip laser optical path between the side laser vibrometers and non-center measurement points on the mass block; and a round-trip laser optical path is formed between the top laser vibrometer and the center measurement point on the mass block.

8. A dynamic calibration method for a sinusoidal force sensor according to claim 7, characterized in that: The frame is provided with a counterweight block for adjusting the natural frequency of the frame, and the bottom of the frame is provided with a shock absorbing device.

9. A dynamic calibration method for a sinusoidal force sensor according to claim 7, characterized in that: The frame is provided with a height adjustment seat, which is adjustably set on the column of the frame; the height adjustment seat is provided with a horizontal angle adjustment mechanism; the horizontal angle adjustment mechanism includes a rotating base installed on the height adjustment seat, the rotating base is rotatably set on the height adjustment seat, and the side laser vibrometer is set on the rotating base; a protrusion is provided on the side of the rotating base, an adjustment seat is provided on the height adjustment seat, and a threaded pusher and an elastic push rod are provided on the adjustment seat, and the threaded pusher and the elastic push rod respectively support the two sides of the protrusion.

10. A dynamic calibration method for a sinusoidal force sensor according to claim 7, characterized in that: A quadrangular pyramid is provided on the reflector frame, and reflectors are provided on the four sides of the quadrangular pyramid; a through hole is provided in the center of the quadrangular pyramid, and the through hole is located directly above the center of the mass block; the through hole is used to allow the laser beam of the top laser vibrometer to pass through.

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