Improvement method for improving frequency precision of electromagnetic MEMS vibration sensor

Abstract

The invention provides an improvement method for improving the frequency precision of an electromagnetic MEMS vibration sensor. The method comprises the following steps: step 1, obtaining a mass block and a natural resonant frequency factor which influence the frequency measurement precision of the electromagnetic MEMS vibration sensor through theoretical simulation; step 2, adjusting based on the obtained mass block and the natural resonant frequency factor to improve the measurement precision of the vibration sensor; and step 3, evaluating and testing the natural resonant frequency of the electromagnetic MEMS vibration sensor. According to the method, key factors influencing the frequency measurement precision of the vibration sensor are analyzed through theoretical simulation, and the measurement precision of the vibration sensor can be improved by adjusting the quality of the module and the natural resonant frequency of the system; according to the method for adjusting the measurement mass block, the measurement precision of the vibration sensor is improved.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to an improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor. Background Art

[0002] Electromagnetic MEMS vibration sensors are composed of two core systems: a vibration detection system and a signal conversion system. The vibration detection system is used to capture external vibrations, while the signal conversion system converts the vibration signal into an electromotive force output. By measuring the magnitude of this electromotive force, we can obtain key parameters such as the acceleration and frequency of the external vibration, and realize the measurement of the vibration signal. In the spring-oscillator structure, the detection mass block will generate an inertial force under the action of acceleration. According to Newton's second law, there is the following conversion relationship between the inertial force and the measured acceleration:

[0003] F inertia = ma (1-1)

[0004] In the formula, F inertia represents the inertial force generated by the detection mass; m represents the weight of the detection mass; a external represents the external input acceleration received by the acceleration sensor, and its direction is the same as the input acceleration direction. The working principle of the vibration sensor is generally based on mechanical vibration. Usually, the physical model of the vibration detection system can be regarded as a mass-spring-damper system. In the whole system, the equivalent mass of the intermediate mass block is m, the stiffness of the cantilever beam is k, and the external damping is b. In the above physical model, the detection mass block m is bound by a high-stiffness spring k. When the external acceleration acts, the inertial force received by the detection mass block m will cause it to perform simple harmonic vibration near the equilibrium position. When the vibration sensor is stationary or moving at a constant speed relative to the inertial system, the internal detection mass block is in an equilibrium position and is stationary relative to the external frame of the vibration sensor. However, when the external frame of the vibration sensor is affected by external acceleration, the internal detection mass block will move relative to the external frame. This relative motion will cause displacement and generate changes in electrical signals through the circuit. By measuring the changes in this signal, the value of the external dynamic acceleration can be determined. Therefore, an improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor is proposed to solve the above problems. Summary of the invention

[0005] In view of this, an object of the present invention is to provide an improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor, so as to at least solve the above problems.

[0006] The technical solution adopted by the present invention is as follows:

[0007] An improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor, the method comprising the following steps:

[0008] Step 1, obtaining the mass block and inherent resonant frequency factors that affect the frequency measurement accuracy of the electromagnetic MEMS vibration sensor through theoretical simulation;

[0009] Step 2, adjusting based on the obtained mass block and natural resonant frequency factors to improve the measurement accuracy of the vibration sensor;

[0010] Step 3: Conduct an evaluation test on the natural resonant frequency of the electromagnetic MEMS vibration sensor.

[0011] Furthermore, in step 1, the module mass and inherent resonant frequency factors affecting the frequency measurement accuracy of the electromagnetic MEMS vibration sensor are obtained through theoretical simulation as follows:

[0012] By analyzing the mechanical model in the vibration detection system, the second-order differential equation of the mechanical model is listed:

[0013]

[0014] Where m is the mass of the structure, x is the displacement of the structure, t is the time of structural movement, b is the equivalent damping coefficient of the system, k is the spring elastic coefficient, and a is the acceleration to be measured in the external environment;

[0015] By performing Laplace transformation on equation (1-2), we can obtain the transmission function from the acceleration signal to the relative displacement of the sensitive mass block:

[0016] ms 2 x(s)+bsx(s)+k(s)=ma(s)(1-3)

[0017]

[0018] In formula (1-4), ω0 is the resonant frequency of the mechanical structure of the vibration sensor, Q is the quality factor of the sensitive mass block, and ζ is the damping ratio factor. The corresponding formula is:

[0019]

[0020] From equation (1-4), it can be concluded that the response of the mass block in the sensitive structure of the MEMS vibration sensor to the acceleration signal is a second-order low-pass system characteristic, and its frequency response expression is as follows (1-8):

[0021]

[0022] The mechanical sensitivity of the vibration sensor is determined by the ratio of the relative displacement x of the sensitive mass block and the acceleration signal a. The general expression is as follows (1-9):

[0023]

[0024] (1) When the external acceleration frequency ω is much smaller than the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is Inversely proportional;

[0025] (2) When the external acceleration frequency ω is close to the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is affected by the mass m of the mass block, the equivalent damping coefficient b of the system and ω0;

[0026] (3) When the external acceleration frequency ω is much larger than the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is related to ω 2 Inversely proportional.

[0027] Further, in step S2, based on the obtained mass block and natural resonant frequency factors, adjustments are made to improve the measurement accuracy of the vibration sensor by analyzing the natural frequency of the sensitive structure composed of the cantilever beam-mass block and optimizing the natural frequency, specifically including the following steps:

[0028] Build a finite element model of the structure, including defining the geometry, material properties, and boundary conditions;

[0029] Set up system constraints to fix the structure in all directions for free vibration analysis;

[0030] Carry out numerical solution and calculate different vibration modes of the structure and the natural frequencies under each mode by numerical methods;

[0031] Set optimization goals by increasing natural frequencies or improving specific vibration modes; check the amplitude, vibration mode and natural frequency of each vibration mode to obtain the vibration characteristics of the structure;

[0032] Repeat the natural frequency analysis to evaluate the natural frequencies and vibration modes of the optimized structure.

[0033] Furthermore, the structural parameters of the sensitive structure include cantilever beam length, cantilever beam width and mass block size.

[0034] Furthermore, in step 3, an evaluation test is performed on the natural resonant frequency of the electromagnetic MEMS vibration sensor, which specifically includes the following steps:

[0035] The electromagnetic vibration sensor and the commercial acceleration sensor are fixed on the vibration table by a clamp to ensure that the excitation acceleration of the two is consistent, and they are both placed in the center of the vibration table;

[0036] The vibration table frequency of the vibration table is set to the natural frequency of the vibration sensor to be tested and its nearby frequency, and the standard acceleration value is determined by referring to the acceleration sensor;

[0037] Increase the excitation acceleration from 0.1g in increments of 0.1g to 3g, and record the output voltage of the vibration sensor under the corresponding standard acceleration in sequence;

[0038] A vibration table and a power amplifier are used to provide sinusoidal vibration with a fixed acceleration and a frequency range of 30 to 200 Hz, which excites the vibration sensor to generate forced vibration and output a voltage signal. The signal is then connected to an oscilloscope and a digital multimeter to record the frequency sweep data.

[0039] The vibration frequency of the vibration table is changed by adjusting the signal generator, starting the test from 30 to 200 Hz with a step of 5 Hz;

[0040] After finding the approximate natural frequency position, continue testing with a step size of 1 Hz to obtain the output voltage of the prototype at different vibration frequencies. When a peak value appears, the corresponding frequency is the natural frequency of the vibration sensor.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention analyzes the key factors that affect the frequency measurement accuracy of the vibration sensor through theoretical simulation, and concludes that the measurement accuracy of the vibration sensor can be improved by adjusting the module mass and the inherent resonant frequency of the system. The method of adjusting the measurement mass block provided by the present invention solves the problem of improving the measurement accuracy of the vibration sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 It is a schematic diagram of the overall process of an embodiment of the present invention.

[0045] Figure 2 It is a schematic diagram of a curve showing the relationship between the cantilever beam length and the natural frequency according to an embodiment of the present invention.

[0046] Figure 3 It is a schematic diagram of a curve showing the relationship between the thickness and width of the cantilever beam and the natural frequency according to an embodiment of the present invention.

[0047] Figure 4 Schematic diagram of the vibration test system according to an embodiment of the present invention.

[0048] Figure 5 Schematic diagram of output waveforms of the electromagnetic vibration sensor and the reference sensor according to an embodiment of the present invention.

[0049] Figure 6 Schematic diagram of the frequency response of the vibration sensor according to the embodiment of the present invention. DETAILED DESCRIPTION

[0050] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The enumerated embodiments are only used to explain the present invention and are not used to limit the scope of the present invention.

[0051] Reference Figure 1 The present invention provides an improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor, the method comprising the following steps:

[0052] Step 1, obtaining the mass block and inherent resonant frequency factors that affect the frequency measurement accuracy of the electromagnetic MEMS vibration sensor through theoretical simulation;

[0053] Step 2: Adjustment is performed based on the obtained mass block and natural resonant frequency factors to improve the measurement accuracy of the vibration sensor.

[0054] In step 1, the module mass and inherent resonant frequency factors that affect the frequency measurement accuracy of the electromagnetic MEMS vibration sensor are obtained through theoretical simulation:

[0055] By analyzing the mechanical model in the vibration detection system, the second-order differential equation of the mechanical model is listed:

[0056]

[0057] Where m is the mass of the structure, x is the displacement of the structure, t is the time of structural movement, b is the equivalent damping coefficient of the system, k is the spring elastic coefficient, and a is the acceleration to be measured in the external environment;

[0058] By performing Laplace transformation on equation (1-2), we can obtain the transmission function from the acceleration signal to the relative displacement of the sensitive mass block:

[0059] ms 2 x(s)+bsx(s)+k(s)=ma(s)(1-3)

[0060]

[0061] In formula (1-4), ω0 is the resonant frequency of the mechanical structure of the vibration sensor, Q is the quality factor of the sensitive mass block, and ζ is the damping ratio factor. The corresponding formula is:

[0062]

[0063] From equation (1-4), it can be concluded that the response of the mass block in the sensitive structure of the MEMS vibration sensor to the acceleration signal is a second-order low-pass system characteristic, and its frequency response expression is as follows (1-8):

[0064]

[0065] The mechanical sensitivity of the vibration sensor is determined by the ratio of the relative displacement x of the sensitive mass block and the acceleration signal a. The general expression is as follows (1-9):

[0066]

[0067] (1) When the external acceleration frequency ω is much smaller than the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is Inversely proportional;

[0068] (2) When the external acceleration frequency ω is close to the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is affected by the mass m of the mass block, the equivalent damping coefficient b of the system and ω0;

[0069] (3) When the external acceleration frequency ω is much larger than the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is related to ω 2 Inversely proportional.

[0070] In step S2, based on the obtained mass block and natural resonant frequency factors, adjustments are made to improve the measurement accuracy of the vibration sensor by analyzing the natural frequency of the sensitive structure composed of the cantilever beam-mass block and optimizing the natural frequency, which specifically includes the following steps:

[0071] Build a finite element model of the structure, including defining the geometry, material properties, and boundary conditions;

[0072] Set up system constraints to fix the structure in all directions for free vibration analysis;

[0073] Carry out numerical solution and calculate different vibration modes of the structure and the natural frequencies under each mode by numerical methods;

[0074] Set optimization goals by increasing natural frequencies or improving specific vibration modes; check the amplitude, vibration mode and natural frequency of each vibration mode to obtain the vibration characteristics of the structure;

[0075] Repeat the natural frequency analysis to evaluate the natural frequencies and vibration modes of the optimized structure.

[0076] The structural parameters of the sensitive structure include cantilever beam length, cantilever beam width and mass block size.

[0077] In step 3, an evaluation test is performed on the natural resonant frequency of the electromagnetic MEMS vibration sensor, which specifically includes the following steps:

[0078] The electromagnetic vibration sensor and the commercial acceleration sensor are fixed on the vibration table by a clamp to ensure that the excitation acceleration of the two is consistent, and they are both placed in the center of the vibration table;

[0079] The vibration table frequency of the vibration table is set to the natural frequency of the vibration sensor to be tested and its nearby frequency, and the standard acceleration value is determined by referring to the acceleration sensor;

[0080] Increase the excitation acceleration from 0.1g in increments of 0.1g to 3g. Record the output voltage of the vibration sensor under the corresponding standard acceleration in sequence;

[0081] A vibration table and a power amplifier are used to provide sinusoidal vibration with a fixed acceleration and a frequency range of 30 to 200 Hz, which excites the vibration sensor to generate forced vibration and output a voltage signal. The signal is then connected to an oscilloscope and a digital multimeter to record the frequency sweep data.

[0082] The vibration frequency of the vibration table is changed by adjusting the signal generator, starting the test from 30 to 200 Hz with a step of 5 Hz;

[0083] After finding the approximate natural frequency position, continue testing with a step size of 1 Hz to obtain the output voltage of the prototype at different vibration frequencies. When a peak value appears, the corresponding frequency is the natural frequency of the vibration sensor.

[0084] Exemplarily, the present invention analyzes the key factors affecting the frequency measurement accuracy of the vibration sensor through theoretical simulation, and the method provided by the present invention solves the method of improving the measurement accuracy of the vibration sensor by adjusting the measurement mass block. And it can be seen from formula (1-8) that there are many parameters that affect the natural frequency of the cantilever beam-mass block sensitive structure. In order to design a reasonable and feasible structure, it is necessary to analyze the influence of each parameter on the natural frequency, and obtain the structural parameters with the best performance through analysis and optimization. The structural parameters of the sensitive structure include the cantilever beam length, cantilever beam width, cantilever beam thickness, cantilever beam spacing, the size of the center mass block, etc. These parameters have different degrees of influence on the natural frequency, so it is necessary to conduct systematic analysis and optimization to determine the best combination of structural parameters, and adjust the design to achieve the desired performance goals.

[0085] The cantilever beam simulation optimization is carried out. According to the structural natural frequency analysis steps, the influence of the cantilever beam length, width and mass block size on the natural frequency of the sensitive structure is discussed. The natural frequency simulation module of the finite element analysis software COMSOL is used to impose boundary constraints in the external frame, and simulation analysis is carried out under different structural parameters to explore the influence of these parameters on the natural frequency of the sensitive structure. Through this process, the purpose is to optimize the structural size and make the design achieve the expected effect. The simulation calculation results refer to Figure 2 , Figure 2 The relationship between the cantilever beam length close to the inner mass and the resonant frequency is shown.

[0086] It can be observed that when the length of the inner cantilever beam increases from 5300μm to 6200μm, the resonant frequency decreases from 82.37Hz to 72.828Hz. The resonant frequency of the sensitive structure of the vibration sensor is inversely proportional to the length of the inner cantilever beam, that is, the longer the inner cantilever beam, the lower the resonant frequency. The length of the inner cantilever beam has a limited effect on the resonant frequency, and even if the length of the structure changes significantly, the frequency changes slightly. In addition, Figure 2 The relationship curve between the cantilever length close to the external frame and the resonant frequency is shown. When the length of the outer cantilever increases from 5600μm to 6500μm, the resonant frequency decreases from 89.968Hz to 71.525Hz. Similar to the case of the inner cantilever, the resonant frequency of the sensitive structure also decreases with the increase of the outer cantilever length, and the change is slightly greater than that of the inner cantilever. Although the increase in the length of the outer cantilever has a certain effect on the resonant frequency, the overall effect is still limited.

[0087] Figure 3 The relationship curve between the cantilever thickness and the resonant frequency is shown. When the cantilever thickness increases from 40μm to 400μm, the resonant frequency decreases slightly from 74.834Hz to 75.398Hz, showing an overall increasing trend, but the change lacks obvious regularity. It should be noted that even if the cantilever thickness increases to 10 times the initial thickness, the resonant frequency only changes slightly by less than 1Hz. This shows that the cantilever thickness has little effect on the resonant frequency of the sensitive structure of the vibration sensor. Therefore, when designing the sensitive structure frequency, the cantilever thickness can be basically ignored. At the same time, Figure 3 shows the relationship curve between the cantilever width and the resonant frequency. When the cantilever width increases from 2μm to 35μm, the resonant frequency increases from 57.589Hz to 93.828Hz, showing a linear change trend. For every 1μm increase in the cantilever width, the resonant frequency will change significantly, highlighting the important influence of the cantilever width on the resonant frequency. Therefore, in the design of the sensitive structure frequency, the optimization design of the cantilever width should be placed in the first place.

[0088] In order to reliably evaluate the parameters including linearity, sensitivity, repeatability, and range, the corresponding vibration test system is designed as follows: Figure 4 The excitation system consisting of a waveform generator, a power amplifier (KSI-758PA100) and a vibration table (KST-758ST50) can provide vibration excitation of multiple waveforms with acceleration below 10g for the collector prototype. The vibration monitoring system consisting of a piezoelectric accelerometer (KSI-108A010.1 50.04mv / m / s2) and an oscilloscope can provide the acceleration and frequency of the vibration provided by the vibration table in real time. The digital multimeter is used to test the voltage across the load.

[0089] A signal amplifier (YB3020) is used to generate a sinusoidal excitation signal of a certain frequency. The excitation signal is then amplified by a power amplifier and transmitted to the vibration table to drive the vibration table to generate sinusoidal vibration in the Z direction at the same frequency and corresponding acceleration.

[0090] In the measurement, the piezoelectric accelerometer is used as a calibration device. After the vibration table generates an acceleration signal, the commercial IEPE piezoelectric accelerometer will generate a reference acceleration value. The reference accelerometer is used for acceleration calibration before the test. It is powered and output by a constant current source circuit, and the accurate acceleration value is obtained by the known sensitivity. Under the calibrated acceleration, the output of the electromagnetic vibration sensor passes through the filter amplifier circuit, and after multiple measurements, a more accurate output voltage is measured by a digital multimeter (DMM6500).

[0091] Perform performance testing and analysis to test the key performance indicators of electromagnetic MEMS vibration sensors, including natural frequency, sensitivity, linearity and range. Perform vibration acceleration calibration. Acceleration calibration is required before frequency response testing to calibrate the acceleration of the vibration table. The experimental test steps are as follows:

[0092] (1) First, fix the electromagnetic vibration sensor and commercial acceleration sensor on the vibration table through a clamp. In order to ensure that the excitation acceleration of the two is consistent, place them in the center of the vibration table.

[0093] (2) Secondly, the vibration table frequency is set to the natural frequency of the vibration sensor to be tested and its nearby frequency, and the standard acceleration value is determined by referring to the acceleration sensor.

[0094] (3) Then increase the excitation acceleration from 0.1g in increments of 0.1g to 3g. Record the output voltage of the vibration sensor under the corresponding standard acceleration in sequence.

[0095] Figure 5The output waveforms of the electromagnetic vibration sensor and the reference accelerometer recorded by the digital oscilloscope under a constant acceleration of 1m / s2 are shown. The reference accelerometer is used for acceleration calibration before the test. The accelerometer can test vibrations within 0.3 to 3500Hz. It can be observed that the output waveform of the electromagnetic vibration sensor is good and close to the standard sine signal.

[0096] Conduct a frequency response test. By applying a series of vibration signals with varying frequencies, the relationship between the output voltage of the vibration sensor and the vibration frequency can be obtained. When the acceleration is constant, the output voltage is measured by testing the signal excitation at different vibration frequencies to obtain the curve relationship between voltage and frequency. The method for performing a frequency response test on a vibration sensor using the previously established test system is as follows:

[0097] (1) A vibration table and a power amplifier are used to provide sinusoidal vibration with a fixed acceleration in the frequency range of 30 to 200 Hz. The vibration sensor is stimulated to generate forced vibration and output a voltage signal. The signal is then connected to an oscilloscope and a digital multimeter to record the frequency sweep data.

[0098] (2) During the experiment, the vibration frequency of the vibration table was changed by adjusting the signal generator, starting from 30 to 200 Hz in steps of 5 Hz.

[0099] (3) After finding the approximate natural frequency position, continue testing with a step size of 1 Hz to obtain the output voltage of the prototype at different vibration frequencies. When a peak value appears, the corresponding frequency is the natural frequency of the vibration sensor. Figure 6 The frequency response curve of the electromagnetic vibration sensor under 0.1g acceleration is shown. It can be seen that there are two significant peaks on the curve, which correspond to the first and second order modal frequencies of the vibration sensor. At 66Hz, the output voltage of the sensor reaches a peak value of 4.3V, which is close to the natural frequency of the sensitive structure obtained by the previous simulation. In addition, the frequency response curve is symmetrical, indicating that the sensitive structure is in the linear vibration range.

[0100] Performance test: The natural frequency of the sensitive structure of the electromagnetic MEMS vibration sensor can be determined by the frequency response test after acceleration calibration. The sensitivity and linearity of the electromagnetic MEMS vibration sensor can be obtained by testing the output voltage of the vibration sensor under different accelerations at the natural frequency of the sensitive structure. Within this frequency range, the sensitivity value of the sensor is less affected by frequency changes. When the vibration frequency fluctuates within this range, the sensor can maintain high sensitivity, thereby ensuring the accuracy of the measurement results.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor, characterized in that: The method comprises the following steps: Step 1, obtaining the mass block and inherent resonant frequency factors that affect the frequency measurement accuracy of the electromagnetic MEMS vibration sensor through theoretical simulation; Step 2, adjusting based on the obtained mass block and natural resonant frequency factors to improve the measurement accuracy of the vibration sensor; Step 3: Conduct an evaluation test on the natural resonant frequency of the electromagnetic MEMS vibration sensor.

2. The improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor according to claim 1, characterized in that: In step 1, the factors of mass block and natural resonant frequency that affect the frequency measurement accuracy of electromagnetic MEMS vibration sensor are obtained through theoretical simulation: By analyzing the mechanical model in the vibration detection system, the second-order differential equation of the mechanical model is listed: Where m is the mass of the structure, x is the displacement of the structure, t is the time of structural movement, b is the equivalent damping coefficient of the system, k is the spring elastic coefficient, and a is the acceleration to be measured in the external environment; By performing Laplace transformation on equation (1-2), we can obtain the transmission function from the acceleration signal to the relative displacement of the sensitive mass block: ms 2 x(s)+bsx(s)+k(s)=ma(s)(1-3) In formula (1-4), ω0 is the resonant frequency of the mechanical structure of the vibration sensor, Q is the quality factor of the sensitive mass block, and ζ is the damping ratio factor. The corresponding formula is: From equation (1-4), it can be concluded that the response of the mass block in the sensitive structure of the MEMS vibration sensor to the acceleration signal is a second-order low-pass system characteristic, and its frequency response expression is as follows (1-8): The mechanical sensitivity of the vibration sensor is determined by the ratio of the relative displacement x of the sensitive mass block and the acceleration signal a. The general expression is as follows (1-9): (1) When the external acceleration frequency ω is much smaller than the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is related to ω0. 2 Inversely proportional; (2) When the external acceleration frequency ω is close to the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is affected by the mass m of the mass block, the equivalent damping coefficient b of the system and ω0; (3) When the external acceleration frequency ω is much larger than the resonant frequency ω0 of the mechanical structure of the vibration sensor, the mechanical sensitivity of the vibration sensor is related to ω 2 Inversely proportional.

3. The improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor according to claim 2, characterized in that: In step S2, based on the obtained mass block and natural resonant frequency factors, adjustments are made to improve the measurement accuracy of the vibration sensor by analyzing the natural frequency of the sensitive structure composed of the cantilever beam-mass block and optimizing the natural frequency, which specifically includes the following steps: Build a finite element model of the structure, including defining the geometry, material properties, and boundary conditions; Set up system constraints to fix the structure in all directions for free vibration analysis; Carry out numerical solution and calculate different vibration modes of the structure and the natural frequencies under each mode by numerical methods; Set optimization goals by increasing natural frequencies or improving specific vibration modes; check the amplitude, vibration mode and natural frequency of each vibration mode to obtain the vibration characteristics of the structure; Repeat the natural frequency analysis to evaluate the natural frequencies and vibration modes of the optimized structure.

4. The improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor according to claim 3, characterized in that: The structural parameters of the sensitive structure include cantilever beam length, cantilever beam width and mass block size.

5. The improved method for improving the frequency accuracy of an electromagnetic MEMS vibration sensor according to claim 4, characterized in that: In step 3, an evaluation test is performed on the natural resonant frequency of the electromagnetic MEMS vibration sensor, which specifically includes the following steps: The electromagnetic vibration sensor and the commercial acceleration sensor are fixed on the vibration table by a clamp to ensure that the excitation acceleration of the two is consistent, and they are both placed in the center of the vibration table; The vibration table frequency of the vibration table is set to the natural frequency of the vibration sensor to be tested and its nearby frequency, and the standard acceleration value is determined by referring to the acceleration sensor; Increase the excitation acceleration from 0.1g in increments of 0.1g to 3g, and record the output voltage of the vibration sensor under the corresponding standard acceleration in sequence; A vibration table and a power amplifier are used to provide sinusoidal vibration with a fixed acceleration and a frequency range of 30 to 200 Hz, which excites the vibration sensor to generate forced vibration and output a voltage signal. The signal is then connected to an oscilloscope and a digital multimeter to record the frequency sweep data. The vibration frequency of the vibration table is changed by adjusting the signal generator, starting the test from 30 to 200 Hz with a step of 5 Hz; After finding the approximate natural frequency position, continue testing with a step size of 1 Hz to obtain the output voltage of the prototype at different vibration frequencies. When a peak value appears, the corresponding frequency is the natural frequency of the vibration sensor.

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