A dynamic calibration method for a sine method force sensor

Abstract

The application discloses a sine method force sensor dynamic calibration method, comprising the following specific steps: step one, placing the force sensor to be detected on a vibration table, setting a mass block on the force sensor, the vibration table, the force sensor and the mass block constituting a test combination, and establishing a finite element simulation model; step two, selecting a measuring point on the upper end surface of the mass block; step three, testing the test combination through a test bench; step four, obtaining acceleration theoretical data of non-central measuring points on the mass block according to the finite element simulation model analysis, comparing and analyzing the acceleration theoretical data with acceleration measured data; if the acceleration theoretical data is consistent with the acceleration measured data, obtaining the acceleration distribution data of the whole mass block through the finite element simulation model. The application can provide the acceleration distribution of the whole mass block through the reliable finite element simulation model, and fundamentally solves the problem that standard force values are not unified due to algorithm simplification.

Description

Technical Field

[0001] This invention relates to the field of sensor calibration technology, and in particular to a dynamic calibration method for a sinusoidal force sensor. Background Technology

[0002] The absolute sinusoidal force calibration device is used for the dynamic characteristic calibration of force sensors. The calibration system mainly consists of a standard vibration table, sensor, mass block, and laser vibrometer (see attached diagram). Figure 6 (As shown). A standard vibration table provides a sinusoidal force at a specific frequency. The lower end of the force sensor is mounted on the vibration table via a lower connector, and the upper end of the upper force sensor is connected to the mass block via an upper connector, thus linking with the standard vibration table. The lens of the laser vibrometer emits a laser beam, which acts on the center point of the upper surface of the mass block to measure the acceleration value of the center point of the upper end of the mass block during the entire system's motion. Then, the dynamic force value borne by the force sensor at a specific frequency is calculated through a corresponding compensation algorithm. This force value can be used as the standard force value for calibrating the system and compared with the force value measured by the force sensor. Then, calibration is performed according to the corresponding indicators.

[0003] Current technology uses only a laser vibrometer to measure the acceleration value at the center point of the upper surface of the mass block, and then uses a compensation algorithm to calculate the acceleration distribution of the entire mass block. However, existing academic research on compensation algorithms is all derived from simplified calibration system models, and different research institutions have provided different simplified compensation algorithms.

[0004] For example: the standard force value of the German Federal Institute of Physics and Technology (PTB) F s The algorithm is as follows:

[0005] ;

[0006] The standard force value of the Beijing Great Wall Institute of Metrology and Testing (CIMM) F s The algorithm is as follows: ;

[0007] Standard force values ​​obtained using different algorithms F s The results will differ, and to ensure consistency, the system model cannot be arbitrarily simplified (different simplification methods will lead to discrepancies in the calculation results). It is necessary to base the model on the actual operating conditions of the calibrated system as much as possible. However, traditional theoretical modeling methods will result in overly complex calculation equations, a significant increase in computational load, and may even make the model unsolvable. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of the prior art by providing a dynamic calibration method for a sinusoidal force sensor.

[0009] The objective of this invention is achieved through the following technical solution: a dynamic calibration method for a sinusoidal force sensor, comprising the following specific steps:

[0010] Step 1: Place the force sensor to be tested on the vibration table, set a mass block on the force sensor, and the vibration table, force sensor and mass block constitute the test assembly, and establish a finite element simulation model including the force sensor and mass block.

[0011] Step 2: Select several measurement points on the upper surface of the mass block; one measurement point is located at the center of the mass block, which is the central measurement point, and the rest are non-central measurement points.

[0012] Step 3: Test the test assembly using a test bench; the test bench is equipped with laser vibration meters corresponding to the measurement points; turn on the vibration table and apply a sinusoidal load to the force sensor and mass block, and make the acceleration value at the center measurement point reach the preset value; at the same time, obtain the actual acceleration data of the non-center measurement points;

[0013] Step 4: Based on the analysis of the finite element simulation model, obtain the theoretical acceleration data of the non-central measurement points on the mass block, 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.

[0014] Preferably, a total of five measurement points are set, of which two non-central measurement points are located at one-third of the radius of the upper surface of the mass block, and two non-central measurement points are located at two-thirds of the radius of the upper surface of the mass block.

[0015] As a preferred method, in step one, a finite element simulation model is established using Ansys Workbench simulation software. The specific method is as follows:

[0016] S1: Create a 3D model of the force sensor and the mass block, and import the 3D model into the simulation software;

[0017] S2: Set the elastic modulus, Poisson's ratio, and density of the mass block and force sensor;

[0018] S3: Mesh the 3D model;

[0019] S4: Perform modal analysis and obtain multi-modes. Import the obtained multi-modes 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 sinusoidal load.

[0020] Preferably, in step S2, when determining the elastic modulus and Poisson's ratio of the force sensor, the initial values ​​of the elastic modulus and Poisson's ratio of the force sensor are first selected, and then 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, actual vibration test is performed on the overall structure composed of the force sensor and the mass block to obtain the relative amplitude curve within the test vibration frequency range.

[0021] If the frequency corresponding to the highest point of the relative amplitude curve is consistent with the natural frequency obtained through modal analysis, then 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, then the initial values ​​of elastic modulus and Poisson's ratio are readjusted, and the above process is repeated.

[0022] As a preferred option, in step three, before turning on the vibration table, first adjust the gain of the vibration table's power amplifier to the lowest level, and then turn on its power; and 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 is working stably, collect the acceleration values ​​at each measurement point through the laser vibrometer; the acquisition time for each measurement is not less than 10 vibration cycles, and repeat the measurement multiple times in the same state, using the average value of multiple measurements as the actual acceleration measurement data.

[0023] Preferably, in step four, if the theoretical acceleration data and the measured acceleration data do not match and the difference between the theoretical acceleration data and the measured acceleration data is less than a set threshold, then the parameters of the mass block and force sensor in the finite element simulation model are adjusted, including Poisson's ratio and elastic modulus; if the theoretical acceleration data and the measured acceleration data do not match and the difference between the theoretical acceleration data and the measured acceleration data is greater than a set threshold, then the finite element simulation model in step one is rebuilt, and a vibration table part is added to the finite element simulation model.

[0024] Preferably, the test bench includes a frame, on which a reflector frame, several lateral laser vibrometers, and a top laser vibrometer are mounted. The vibration table on the test assembly is separated from the frame. The reflector frame is equipped with reflectors corresponding to the lateral laser vibrometers. The reflectors enable the lateral laser vibrometers to form a laser round-trip optical path with the non-central measurement points on the mass block, and the top laser vibrometer to form a laser round-trip optical path with the central measurement point on the mass block.

[0025] Preferably, the frame is provided with a counterweight for adjusting the frame's natural frequency, and the bottom of the frame is provided with a shock-absorbing device.

[0026] Preferably, the frame is provided with a height adjustment seat, which is adjustablely mounted on the upright of the frame. The height adjustment seat is provided with a horizontal angle adjustment mechanism, which includes a rotating base mounted on the height adjustment seat. The rotating base is rotatably mounted on the height adjustment seat, and a side laser vibration meter is mounted 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. The threaded pusher and the elastic push rod respectively press against the two sides of the protrusion.

[0027] Preferably, a quadrangular pyramid is provided on the reflector frame, and the reflector is 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.

[0028] The beneficial effects of this invention are:

[0029] 1. In this invention, the test bench's ability to perform local multi-point detection is achieved by setting multiple measurement points (center measurement point + non-center measurement points) on the mass block and simultaneously measuring with multiple laser vibrometers on the test bench to obtain acceleration values ​​at different points on the mass block. By comparing and analyzing the measured acceleration data at different points with the theoretical data obtained from the finite element simulation model, the accuracy of the finite element simulation model is verified and corrected. The simultaneous measurement at multiple points allows for the acquisition of acceleration data at different locations on the mass block, so that the verification of the finite element simulation model no longer relies on data from a single center point, but is based on comparison of multi-point measured data, which greatly improves the pertinence and accuracy of model correction.

[0030] 2. This 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 makes the calculation of standard force values ​​based on more complete physical field information, improving the accuracy and reliability of force value estimation; and this invention directly verifies and corrects the finite element model through measured multi-point acceleration, without relying on specific compensation algorithms, fundamentally solving the problem of inconsistent standard force values ​​caused by algorithm simplification.

[0031] 3. Traditional methods relying on theoretical derivation and compensation algorithm correction are difficult to solve due to the complexity of the equations. However, this invention uses finite element simulation combined with experimental data correction, which ensures the realism of the model while avoiding complex theoretical derivation. The efficient computing power of finite element software makes large-scale model analysis possible, achieving a balance between computational efficiency and accuracy. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the test bench of the present invention.

[0033] Figure 2 This is a schematic diagram of the reflector frame.

[0034] Figure 3 This is a partial structural diagram of the laser vibration meter located on the side of the test bench.

[0035] Figure 4 This is a schematic diagram showing the distribution of measurement points on the upper surface of the mass block in this invention.

[0036] Figure 5 This is a schematic diagram of mesh generation for a 3D model.

[0037] Figure 6 This is a schematic diagram of a calibration system in the prior art, consisting of a standard vibration table, a sensor, a mass block, and a laser vibration meter.

[0038] In the diagram: 1. Frame, 2. Mounting platform, 3. Reflector frame, 4. Vibration table, 5. Force sensor, 6. Mass block, 7. Side laser vibration meter, 8. Top laser vibration meter, 9. Counterweight, 10. Level, 11. Top movable part, 12. Vibration damping device, 13. Four-sided pyramid, 14. Reflector, 15. Through hole, 16. Height adjustment seat, 17. Rotating base, 18. Positioning component, 19. Elastic jacking column, 20. Adjustment seat, 21. Threaded pusher, 22. Elastic push rod, 23. Protrusion. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0040] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0041] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0042] This invention discloses a dynamic calibration method for a sinusoidal force sensor 5, comprising the following specific steps:

[0043] Step 1: Place the force sensor 5 to be tested on the vibration table 4, and set the mass block 6 on the force sensor 5. The vibration table 4, the force sensor 5 and the mass block 6 constitute the test assembly, and establish a finite element simulation model including the force sensor 5 and the mass block 6.

[0044] Step 2: Select several measurement points on the upper surface of mass block 6; one of the measurement points is located at the center of mass block 6, which is the central measurement point, and the rest are non-central measurement points.

[0045] Step 3: Test the test assembly using a test bench; the test bench is equipped with laser vibration meters that correspond one-to-one with the measurement points; turn on the vibration table 4 and apply a sinusoidal load to the force sensor 5 and the mass block 6, and make the acceleration value of the center measurement point reach the preset value; at the same time, obtain the actual acceleration data of the non-center measurement points.

[0046] Step 4: Based on the analysis of the finite element simulation model, obtain the theoretical acceleration data of the non-central measurement points on mass block 6, 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 6 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.

[0047] In step four, if the theoretical acceleration data matches the measured acceleration data, it indicates that the finite element simulation model has passed verification and its accuracy meets the requirements. Once the finite element simulation model has passed verification, the acceleration value at any location can be obtained through it. The harmonic response analysis process of the finite element simulation model yields the acceleration response curve of any desired location in mass block 6 and force sensor 5 under sinusoidal load. This result can be considered as the standard acceleration result borne by the sensor. Multiplying the standard acceleration result by the mass borne by the sensor yields the standard force curve, which can be used to calibrate force sensor 5.

[0048] In this invention, the test bench's ability to perform local multi-point detection is achieved by setting multiple measurement points (center measurement point + non-center measurement points) on the mass block 6 and simultaneously measuring with multiple laser vibrometers on the test bench to obtain acceleration values ​​at different points on the mass block 6. By comparing and analyzing the measured acceleration data at different points with the theoretical data obtained from the finite element simulation model, the accuracy of the finite element simulation model is verified and corrected. The simultaneous measurement at multiple points allows for the acquisition of acceleration data at different locations on the mass block 6, so that the verification of the finite element simulation model no longer relies on data from a single center point, but is based on comparison of multi-point measured data, which greatly improves the pertinence and accuracy of model correction.

[0049] Once the finite element simulation model is verified, a reliable finite element simulation model can provide the acceleration distribution over 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 estimation. Traditional calculation methods, however, use simplified compensation algorithms to estimate acceleration data at different locations, which have significant errors. Furthermore, existing technologies rely on simplified compensation algorithms to estimate the standard force value, and different algorithms lead to differences in calculation results (i.e., inconsistent calculation methods). This invention, however, directly verifies and corrects the finite element model through measured multi-point acceleration, without relying on a specific compensation algorithm, fundamentally solving the problem of inconsistent standard force values ​​caused by algorithm simplification.

[0050] Traditional methods relying on theoretical derivation and compensation algorithm correction are difficult to solve due to the complexity of the equations. However, this invention uses finite element simulation combined with experimental data correction, which ensures the realism of the model while avoiding complex theoretical derivation. The efficient computing power of finite element software makes large-scale model analysis possible, achieving a balance between computational efficiency and accuracy.

[0051] This invention adopts a technical approach 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. It significantly improves the accuracy, reliability and repeatability of dynamic calibration of force sensor 5, and has important engineering application value and technological innovation significance.

[0052] like Figure 4 As shown, in this embodiment, a total of five measurement points are set, of which two non-central measurement points are located at one-third of the radius of the upper surface of the mass block 6, and two non-central measurement points are located at two-thirds of the radius of the upper surface of the mass block 6.

[0053] Specifically, in step one, a finite element simulation model is established using Ansys Workbench simulation software. The specific method is as follows:

[0054] S1: Create a 3D model of force sensor 5 and mass block 6, and import the 3D model into the simulation software.

[0055] S2: Set the elastic modulus, Poisson's ratio, and density of mass block 6 and force sensor 5.

[0056] S3: Mesh the 3D model; for details on meshing the 3D model, please refer to the appendix. Figure 5 Appendix Figure 5 In the diagram, the larger cylinder is the mass block 6, and the smaller cylinder is the force sensor 5.

[0057] S4: Perform modal analysis and obtain multi-modes. Import the obtained multi-modes 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 sinusoidal load.

[0058] In step S2, when determining the elastic modulus and Poisson's ratio of the force sensor 5, initial values ​​for the elastic modulus and Poisson's ratio of the force sensor 5 are first selected. Then, modal analysis is performed on the overall structure composed of the force sensor 5 and the mass block 6 to obtain the natural frequency of the overall structure. Then, actual vibration tests are conducted 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 modal analysis, the current initial values ​​for 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 modal analysis, the initial values ​​for the elastic modulus and Poisson's ratio are readjusted, and the above process is repeated.

[0059] Since mass block 6 is made of a single material, its density, elastic modulus, Poisson's ratio, and other parameters are known. However, force sensor 5, due to its complex structure and not being made of a single material, has its density determined by measuring its mass and volume, but its elastic modulus and Poisson's ratio are difficult to obtain directly. In this invention, the elastic modulus and Poisson's ratio of the sensor are determined using an equivalent method. When selecting initial values ​​for the elastic modulus and Poisson's ratio of force sensor 5, a preliminary value can be assumed based on the sensor's material. For example, if force sensor 5 is entirely made of steel, the elastic modulus can be 210 GPa, 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 made to closely match the actual system. After 3-5 iterations, the frequency matching error can be controlled within 1%.

[0060] Traditional methods require separate testing of the elastic modulus and Poisson's ratio for each component of the force sensor 5, but this is difficult to achieve with complex structures (such as multi-material stacks or internal strain beams). This invention uses the overall system's dynamic response to infer parameters, directly obtaining equivalent material parameters without disassembling the sensor, making it applicable to force sensors 5 of any structural form. This innovative method of inferring material parameters from the system-level dynamic response solves the problem of directly measuring the elastic modulus and Poisson's ratio of complex structure force sensors 5, significantly improving the accuracy and calibration efficiency of the finite element model, and providing key technical support for high-precision dynamic force measurement.

[0061] In step three, before turning on the vibration table 4, first adjust the gain of the power amplifier of the vibration table 4 to the lowest level, and then turn on its power; and adjust the gain of the power amplifier of the vibration table 4 so that the acceleration value of the center measurement point reaches the preset value; after the laser vibrometer is working stably, collect the acceleration values ​​of each measurement point through the laser vibrometer; the acquisition time for each measurement is not less than 10 vibration cycles, and repeat the measurement multiple times in the same state, and use the average value of multiple measurements as the actual acceleration measurement data.

[0062] Furthermore, in step four, when the theoretical acceleration data and the measured acceleration data do not match 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 6 and the force sensor 5 in the finite element simulation model are adjusted, including Poisson's ratio and elastic modulus; when the theoretical acceleration data and the measured acceleration data do not match 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 the vibration table 4 part is added to the finite element simulation model.

[0063] In this invention, when theoretical acceleration data and measured acceleration data do not match, parameter correction or model reconstruction is employed. When the difference is less than a set threshold, i.e., the difference between theoretical and measured acceleration data is small (not exceeding the threshold), it indicates that the structural framework of the finite element simulation model is reasonable, but the model parameters (such as elastic modulus and Poisson's ratio) deviate from reality to some extent. In this case, by adjusting these parameters, the dynamic characteristics of the structure in the model, such as stiffness and damping, can be directly corrected, making the simulation results closer to the actual vibration response. This eliminates the need to rebuild the entire model, performing iterative optimization only on material parameters, reducing computational load and debugging time. It is suitable for minor errors caused by material parameter deviations, improving simulation efficiency.

[0064] When the difference exceeds the threshold, the surface model may have systematic errors, ignoring the influence of key physical components (such as the shaking 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 shaking table 4 part, the model can fully consider the dynamic characteristics of the excitation source (such as mass, stiffness, and vibration transmission mode), avoid data deviation caused by simplifying the model, and fundamentally solve the systematic errors of the finite element simulation model.

[0065] The phased optimization strategy for finite element simulation models in this invention distinguishes error types by using threshold judgments. For small errors, the focus is on adjusting model parameters; for large errors, the emphasis is on rebuilding the model structure. This avoids a "one-size-fits-all" approach to model modification and minimizes unnecessary computation while ensuring model accuracy. Directly rebuilding the finite element simulation model for deviations less than a set threshold would significantly increase workload and waste computational resources; while simply adjusting parameters for large errors would fail to address the systematic errors in the finite element simulation model.

[0066] The parameters (elastic modulus, Poisson's ratio, etc.) of the vibration table 4 are determined in the same way as those of the force sensor 5.

[0067] like Figure 1 As shown, the test bench includes a frame 1, on which a reflector frame 3, several lateral laser vibrometers 7, and a top laser vibrometer 8 are mounted. The vibration table 4 on the test assembly is separated from the frame 1. The reflector frame 3 is equipped with reflectors 14 that correspond one-to-one with the lateral laser vibrometers 7. The reflectors 14 enable the lateral laser vibrometers 7 to form a laser round-trip optical path between the lateral laser vibrometers 7 and the non-central measurement points on the mass block 6; the top laser vibrometer 8 forms a laser round-trip optical path between the central measurement point on the mass block 6.

[0068] The frame 1 is constructed of 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 for checking the levelness of the mounting platform 2 is installed on the mounting platform 2. The test assembly is positioned directly below the reflector frame 3. The reflector 14 on the reflector frame 3 is placed at a 45-degree angle. The laser beam emitted by the side laser vibrometer 7 is reflected by the reflector 14 and then shines on the measurement point on the upper surface of the mass block 6. After being reflected by the mass block 6, the laser beam returns to the side laser vibrometer 7 along the same path. Meanwhile, the laser beam emitted by the top laser vibrometer 8 directly shines on the center of the upper surface of the mass block 6 from the top, and after being reflected by the mass block 6, returns to the top laser vibrometer 8 along the same path.

[0069] Currently available laser vibrometers are relatively large, while the mass block 6 in a sinusoidal force standard device with a small measurement range (e.g., force range of 10N-250N) is relatively small. If two or more laser vibrometers are placed side-by-side vertically upside down, the large lens spacing prevents the projected laser beams from completely hitting the upper surface of the mass block 6. The test bench in this invention effectively solves this problem. The test bench uses multiple reflectors 14 to change the laser path, ensuring that the laser beams emitted by each side laser vibrometer 7 accurately hit the measurement points on the upper surface of the mass block 6, thus meeting the testing and calibration requirements of the force sensor 5.

[0070] A counterweight 9 is provided on the frame 1 to adjust its natural frequency, and a vibration damping device 12 is provided at the bottom of the frame 1. Although the vibration table 4 is separate from the frame 1, its vibration during operation may be transmitted to the frame 1 through the ground or base, which may adversely affect the accuracy of the measurement. In this 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, improve the stability of the frame 1, and reduce the vibration impact of the vibration table 4 on the frame 1. The vibration damping device 12 provided at the bottom of the frame 1 can effectively isolate the frame 1 from vibration, further reducing the impact of external vibrations on the frame 1 and ensuring the reliability of the test results.

[0071] like Figure 2 As shown, a quadrangular pyramid 13 is provided on the reflector frame 3, and a reflector 14 is provided on the four sides of the quadrangular pyramid 13; a through hole 15 is provided in 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 vibration meter 8 to pass through.

[0072] like Figure 3 As shown, a height adjustment seat 16 is provided on the frame 1. The height adjustment seat 16 is adjustablely mounted on the column of the frame 1. A horizontal angle adjustment mechanism is provided on the height adjustment seat 16. The horizontal angle adjustment mechanism includes a rotating base 17 mounted on the height adjustment seat 16. The rotating base 17 is rotatably mounted on the height adjustment seat 16. A side laser vibration meter 7 is mounted on the rotating base 17. A protrusion 23 is provided on the side of the rotating base 17. An adjustment seat 20 is provided on the height adjustment seat 16. A threaded pusher 21 and an elastic push rod 22 are provided on the adjustment seat 20. The threaded pusher 21 and the elastic push rod 22 respectively press against the two sides of the protrusion 23.

[0073] The height adjustment seat 16 is used to adjust the height of the side laser vibration meter 7, and the rotating base 17 is used to adjust the horizontal direction of the side laser vibration meter 7. By precisely adjusting the height and horizontal direction of the side laser vibration meter 7, the laser emitted by the side laser vibration meter 7 can accurately fall on the measurement point on the mass block 6. Specifically, when the rotating base 17 is stationary, the elastic push rod 22 applies elastic pressure to the protrusion 23 in the direction of the threaded pusher 21, thereby pressing the protrusion 23 tightly between the elastic push rod 22 and the threaded pusher 21. When it is necessary to adjust the horizontal direction of the side laser vibration meter 7, the protrusion 23 is moved by rotating the threaded pusher 21. As the protrusion 23 moves, it drives the rotating base 17 to rotate, thereby adjusting the horizontal direction of the side laser vibration meter 7.

[0074] The rotating base 17 is cylindrical. A positioning element 18 and an elastic pressing column 19 are provided on the height adjustment seat 16. The positioning element 18 and the elastic pressing column 19 are located on both sides of the rotating base 17. The positioning element 18 is provided with an arc-shaped positioning surface that matches the side of the rotating base 17. The side of the rotating base 17 is in contact with the arc-shaped positioning surface. The elastic pressing column 19 applies elastic pressure to the side of the rotating base 17. This elastic pressure is directed towards the positioning element 18. Under the action of this elastic pressure, the rotating base 17 can stably abut against the arc-shaped positioning surface of the positioning element 18.

[0075] The top of the frame 1 is equipped with a guide rail, on which an adjustable top movable part 11 is mounted. The top laser vibrometer is mounted on the top movable part 11. The top movable part 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.

[0076] The laser vibration meter of this invention employs the laser Doppler principle; when a laser beam irradiates the surface of a moving object, the frequency of the reflected light changes due to the object's motion, and this frequency change is proportional to the object's velocity. By measuring the frequency difference between the reflected light and the incident light, the vibration velocity of the object can be calculated, and thus parameters such as the vibration amplitude and acceleration can be obtained.

[0077] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A dynamic calibration method for a sinusoidal force sensor, characterized in that, The specific steps include the following: Step 1: Place the force sensor to be tested on the vibration table, set a mass block on the force sensor, and the vibration table, force sensor and mass block constitute the test assembly, and establish a finite element simulation model including the force sensor and mass block. Step 2: Select several measurement points on the upper surface of the mass block; one measurement point is located at the center of the mass block, which is the central measurement point, and the rest are non-central measurement points. Step 3: Test the test assembly using a test bench; the test bench is equipped with laser vibration meters corresponding to the measurement points; turn on the vibration table and apply a sinusoidal load to the force sensor and mass block, and make the acceleration value at the center measurement point reach the preset value; at the same time, obtain the actual acceleration data of the non-center measurement points; Step 4: Based on the analysis of the finite element simulation model, obtain the theoretical acceleration data of the non-central measurement points on the mass block, 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. The dynamic calibration method for a sinusoidal force sensor according to claim 1, characterized in that, A total of five measurement points are set, of which two non-central measurement points are located at one-third of the radius of the upper surface of the mass block, and two non-central measurement points are located at two-thirds of the radius of the upper surface of the mass block.

3. The dynamic calibration method for a sinusoidal force sensor according to claim 1, characterized in that, In step one, a finite element simulation model is established using Ansys Workbench simulation software. The specific method is as follows: S1: Create a 3D model of the force sensor and the mass block, and import the 3D 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 3D model; S4: Perform modal analysis and obtain multi-modes. Import the obtained multi-modes 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 sinusoidal load.

4. The 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, the initial values ​​of the elastic modulus and Poisson's ratio of the force sensor are first selected. Then, 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, actual vibration tests are performed on the overall structure composed of the force sensor and the mass block to obtain the 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, then 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, then the initial values ​​of the elastic modulus and Poisson's ratio should be readjusted, and the above process should be repeated.

5. The dynamic calibration method for a sinusoidal force sensor according to claim 1, characterized in that, In step three, before turning on the vibration table, first adjust the gain of the vibration table's power amplifier to the lowest level, and then turn on its power; then 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 is working stably, collect the acceleration values ​​at each measurement point through the laser vibrometer; the acquisition time for each measurement should not be less than 10 vibration cycles, and repeat the measurement multiple times in the same state, using the average value of multiple measurements as the actual acceleration measurement data.

6. The dynamic calibration method for a sinusoidal force sensor according to claim 1, characterized in that, In step four, if the theoretical acceleration data and the measured acceleration data do not match and the difference between them is less than a set threshold, the parameters of the mass block and force sensor in the finite element simulation model are adjusted, including Poisson's ratio and elastic modulus. If the theoretical acceleration data and the measured acceleration data do not match and the difference between them is greater than a set threshold, the finite element simulation model in step one is rebuilt, and a vibration table is added to the finite element simulation model.

7. The dynamic calibration method for a sinusoidal force sensor according to claim 1, characterized in that, The test bench includes a frame, on which a reflector frame, several lateral laser vibrometers, and a top laser vibrometer are mounted. The vibration table on the test assembly is separate from the frame. The reflector frame is equipped with reflectors corresponding to the lateral laser vibrometers. The reflectors enable the lateral laser vibrometers to form a laser round-trip optical path with the non-central measurement points on the mass block, and the top laser vibrometer to form a laser round-trip optical path with the central measurement point on the mass block.

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

9. The dynamic calibration method for a sinusoidal force sensor according to claim 7, characterized in that, The frame is equipped with a height adjustment seat, which is adjustablely mounted on the frame's uprights. The height adjustment seat is equipped with a horizontal angle adjustment mechanism, which includes a rotating base mounted on the height adjustment seat. The rotating base is rotatably mounted on the height adjustment seat, and a side laser vibration meter is mounted on the rotating base. The side of the rotating base is provided with a protrusion. The height adjustment seat is equipped with an adjustment seat, which is equipped with a threaded pusher and an elastic push rod. The threaded pusher and the elastic push rod respectively abut against both sides of the protrusion.

10. The 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 the reflector is 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 vibration meter to pass through.

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