Compensation method for vibration measuring instrument, vibration measuring instrument

Abstract

The present invention provides a compensation method for a vibration measuring instrument and a vibration measuring instrument, the method comprising: acquiring time domain data, obtaining spectrum data through FFT transformation; drawing an amplitude-frequency curve for analysis according to the FFT transformation result; correcting the corresponding spectrum line according to the analysis result; and recalculating the effective value RMS according to the corrected data. The inventor of the present application has found through research that the reason why the value obtained by the vibration measuring instrument when testing the vibration signal is not accurate enough is that the frequency response curve of the acceleration sensor is not ideal. The present invention adopts a frequency domain compensation method, that is, obtaining the spectrum through FFT transformation, correcting the corresponding spectrum line, and then recalculating the effective value, thereby solving the problem of the unideal frequency response curve of the acceleration sensor and improving the accuracy of the vibration measuring instrument.

Description

Technical Field

[0001] The invention belongs to the field of vibration equipment state detection, and in particular, relates to a compensation method of a vibration measuring instrument and a vibration measuring instrument. Background Art

[0002] MEMS accelerometers are manufactured using Micro-Electro-Mechanical Systems (MEMS) technology. This technology integrates mechanical systems and electronic circuits in a very small size using silicon semiconductor processing technology. The mechanical system converts vibration signals into electrical signals, and the electronic circuit completes the acquisition and processing of electrical signals. The two form a collaborative system to achieve intelligent detection and analysis of vibration signals. However, the values ​​obtained by vibration meters using MEMS accelerometers when testing vibration signals are not accurate enough. Summary of the invention

[0003] The present application provides a compensation method for a vibration measuring instrument and a vibration measuring instrument, which improve the accuracy of vibration signal testing.

[0004] In a first aspect, the present application provides a compensation method for a vibration measuring instrument, comprising:

[0005] S101, acquiring time domain data, and obtaining spectrum data through FFT transformation;

[0006] S103, drawing an amplitude-frequency curve for analysis based on the FFT transformation result;

[0007] S105, correcting the corresponding spectral line according to the analysis result;

[0008] S107, recalculating the effective value RMS according to the corrected data.

[0009] Wherein, S101, acquiring time domain data, and obtaining spectrum data through FFT transformation, includes:

[0010] Get the original time domain data at f=160Hz, a total of 2048 discrete data, and perform FFT transformation on it.

[0011]

[0012] in , open Matlab, import the original time domain data, a total of 2048 points, call the fft(X,N) function, and you can get 2048 complex numbers, which are the transformation results of FFT.

[0013] Wherein, S103, drawing an amplitude-frequency curve for analysis according to the FFT transformation result, includes:

[0014] After FFT transformation, the amplitude-frequency curve, i.e., the spectrum, is drawn according to the result; the sampling frequency of the vibration meter is 25KHz, so the interval of the spectrum curve, i.e., the frequency resolution, is 25000 / 2048, which is rounded to 12, in units of Hz; the amplitude-frequency curve shows that there are pulses greater than the preset value at the 14th and 2034th spectrum lines, and the signal frequency corresponding to the 14th spectrum line is 14 times 12, which is 168Hz.

[0015] Wherein, S105, according to the analysis result, corrects the corresponding spectral line, including:

[0016] In the process of testing the frequency response curve, it was found that when f=160Hz, the effective value measured by the acceleration sensor AD1002 was only 1 / 1.5 of the reference value. Therefore, when making frequency domain compensation, the 160Hz point of the frequency response curve of the acceleration sensor AD1002 and the spectrum line symmetrical to it were corrected.

[0017] Wherein, S107, recalculating the effective value RMS according to the corrected data, includes:

[0018] According to Parseval's theorem:

[0019]

[0020] That is, the energy in the time domain is equal to the energy in its transform domain;

[0021] The time domain energy is , the frequency domain energy is ,

[0022] Where Ttotal is the total time, P(fn) is the nth power spectrum density value, △f is the FFT frequency interval,

[0023] Subtract Ttotal from both sides of the equation, and we have ,

[0024] in , N is the block length of FFT, and fs is the sampling frequency.

[0025] It also includes: using software integration to calculate velocity and displacement values, and the velocity and displacement have a first-order integral and a second-order integral relationship with acceleration.

[0026] In a second aspect, the present application provides a vibration measuring instrument, wherein the vibration measuring instrument is configured as follows:

[0027] Obtain time domain data and obtain spectrum data through FFT transformation;

[0028] Draw the amplitude-frequency curve according to the FFT transformation results for analysis;

[0029] According to the analysis results, the corresponding spectral lines are corrected;

[0030] Recalculate the effective value RMS based on the corrected data.

[0031] The vibration measuring instrument is configured to obtain the original time domain data at f=160Hz, a total of 2048 discrete data, and perform FFT transformation on them.

[0032]

[0033] in , open Matlab, import the original time domain data, a total of 2048 points, call the fft(X,N) function, and you can get 2048 complex numbers, which are the transformation results of FFT.

[0034] Among them, the vibration measuring instrument is configured as follows: after FFT transformation, an amplitude-frequency curve, i.e., a spectrum, is drawn according to the result; the sampling frequency of the vibration measuring instrument is 25KHz, so the interval of the spectrum curve, i.e., the frequency resolution is 25000 / 2048, which is rounded to 12, in units of Hz; through the amplitude-frequency curve, it is obtained that there are pulses greater than the preset value at the 14th and 2034th spectrum lines, and the signal frequency corresponding to the 14th spectrum line is 14 times 12, which is 168Hz.

[0035] In a third aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of any of the above methods when executed by a processor.

[0036] The compensation method and vibration measuring instrument of the present application have the following beneficial effects:

[0037] The inventors of the present application have discovered through research that the reason why the values ​​obtained by the vibration meter when testing the vibration signal are not accurate enough is that the frequency response curve of the acceleration sensor is not ideal. The present invention adopts a frequency domain compensation method, that is, obtaining the spectrum through FFT transformation, correcting the corresponding spectrum line, and then recalculating the effective value, thereby solving the problem of the unsatisfactory frequency response curve of the acceleration sensor and improving the accuracy of the vibration measuring instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 To calibrate at the signal frequency f = 80 Hz, then adjust the signal frequency to 150 Hz, 200 Hz, etc., the ratio of the effective value measured by the AD1002 sensor to the effective value of the standard sensor;

[0039] Figure 2 A flow chart of a compensation method for a vibration measuring instrument of the present application;

[0040] Figure 3 It is the amplitude-frequency curve drawn according to the result after FFT transformation;

[0041] Figure 4 A block diagram of one integration in this application;

[0042] Figure 5 For the assumed acceleration signal, some high-frequency noise is superimposed on the sine wave signal;

[0043] Figure 6 is the speed signal obtained after one integration;

[0044] Figure 7 is the displacement signal obtained after the second integration;

[0045] Figure 8 A block diagram of the connections for the equipment developed and tested in this application. DETAILED DESCRIPTION

[0046] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0047] In the following introduction, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The following introduction provides multiple embodiments of the present invention, and different embodiments can be replaced or combined, so this application can also be considered to include all possible combinations of the same and / or different embodiments recorded. Therefore, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more of all other possible combinations of features A, B, C, and D, even though the embodiment may not be clearly recorded in the following text.

[0048] The application fields of this application include: vibration equipment status detection, motor detection, and vibration laboratory.

[0049] The inventor of this application has found through research that the frequency response curve of the MEMS acceleration sensor AD1002 used in the vibration meter of this application is not ideal, which will lead to inaccurate values ​​obtained by the vibration meter when testing vibration signals of certain frequencies. Calibrate at the signal frequency f=80Hz, then adjust the signal frequency to 150Hz, 200Hz, etc., record the ratio of the effective value measured by the AD1002 sensor to the effective value of the standard sensor, Figure 1 For the curve drawn, Figure 1 As shown in the figure, when the signal frequency is around 150Hz, the acceleration value measured by AD1002 is only 75% of the standard value, which is a large error and needs to be compensated in the frequency domain to obtain the ideal result.

[0050] The present invention adopts a frequency domain compensation method, that is, obtains the spectrum through FFT transformation, corrects the corresponding spectrum line, and then recalculates the effective value, thereby solving the problem of unsatisfactory frequency response curve of AD1002. In addition, the vibration meter of the present application adopts a software integration solution, which saves costs.

[0051] like Figure 2 As shown, the compensation method of the vibration measuring instrument of the present application includes: S101, acquiring time domain data, and obtaining spectrum data through FFT transformation; S103, drawing an amplitude-frequency curve for analysis based on the FFT transformation result; S105, correcting the corresponding spectrum line based on the analysis result; S107, recalculating the effective value RMS based on the corrected data. Each step is introduced below.

[0052] (1) FFT transformation

[0053] Here we take the signal frequency f=160Hz as an example.

[0054] First, the original time domain data at f=160Hz is obtained, a total of 2048 discrete data, and FFT (Fast Fourier Transform) is performed on it.

[0055]

[0056] in .

[0057] Open Matlab and import the original time domain data, a total of 2048 points. Call the fft(X,N) function to get 2048 complex numbers, which are the transformation results of FFT.

[0058] (2) Spectrum analysis

[0059] After FFT transformation, the amplitude-frequency curve, i.e., the spectrum, can be drawn according to the result, such as Figure 3 As shown, the sampling frequency of the vibration meter of the present application is 25KHz, so the interval of the spectrum curve, that is, the frequency resolution is 25000 / 2048, which is rounded to 12, and the unit is Hz. Figure 3 In the spectral line, there are large pulses at the 14th and 2034th spectral lines. The signal frequency corresponding to the 14th spectral line is 14 times 12, which is 168 Hz. This is basically consistent with the collected signal frequency.

[0060] (3) Frequency domain compensation

[0061] In the process of testing the frequency response curve previously, it was found that when f=160Hz, the effective value measured by AD1002 was only 1 / 1.5 of the reference value. Therefore, when making frequency domain compensation, the 160Hz point of the frequency response curve of AD1002 and the spectrum line symmetrical to it were corrected.

[0062] (4) Recalculate the effective value RMS

[0063] Directly calculate the effective value in the frequency domain. Its theoretical basis is Parseval's theorem:

[0064]

[0065] That is, the energy in the time domain is equal to the energy in its transform domain.

[0066] The time domain energy is , the frequency domain energy is

[0067] Where Ttotal is the total time, P(fn) is the nth power spectrum density value, and △f is the FFT frequency interval

[0068] Subtract Ttotal from both sides of the equation, and we have

[0069] in , N is the block length of FFT, and fs is the sampling frequency.

[0070] (5) Software integration calculation of speed and displacement

[0071] Through the previous four steps, the acceleration value has been obtained and displayed.

[0072] The vibration meter of this application can also calculate and display the velocity and displacement values, which are in a first-integral and second-integral relationship with acceleration. Regarding integration, the hardware integration method is usually used, but it is costly and consumes a lot of power. The vibration meter of this application uses software integration, which saves costs, reduces power consumption, and the integration effect meets the measurement requirements. Figure 4 is a block diagram of an integral, such as Figure 4 As shown, including high-pass filter, adder, integration and low-pass, the second integration goes through the same process after the first integration.

[0073] This application has the following effects:

[0074] (1) Effect of frequency domain compensation

[0075] By comparing the error of the vibration signal values ​​measured before and after frequency domain compensation, it can be found that this solution has effectively solved the problem of unsatisfactory frequency response curve. The following table shows the performance of the vibration meter under different vibration intensities when the vibration signal frequency is 160Hz.

[0076]

[0077] (2) Effect of points

[0078] Figure 5 is the assumed acceleration signal, such as Figure 5 As shown in the figure, some high-frequency noise is superimposed on the sine wave signal. After filtering and integration, the result of one integration is obtained, that is, the speed signal. Figure 6 is the velocity signal. After another integration, we can get the displacement signal. Figure 7 is the displacement signal. Figure 6-7 As shown in the figure, after integration, the noise of the data is significantly reduced, and the value does not drift. The effective value calculated using such velocity and acceleration signals meets the engineering requirements.

[0079] like Figure 8 As shown, the development and testing equipment of the present application includes: a signal source, a modal exciter, a MEMS accelerometer, a vibration meter, a standard accelerometer, a data collector, and a PC data acquisition software. The signal source is connected to the modal exciter, the modal exciter is respectively connected to the MEMS accelerometer and the standard accelerometer, the MEMS accelerometer is connected to the vibration meter, and the standard accelerometer is connected to the data collector and the PC data acquisition software in sequence.

[0080] The present application also provides a vibration measuring instrument, which is configured to: acquire time domain data and obtain spectrum data through FFT transformation; draw an amplitude-frequency curve for analysis based on the FFT transformation result; correct the corresponding spectrum line based on the analysis result; and recalculate the effective value RMS based on the corrected data.

[0081] The vibration measuring instrument is configured to obtain the original time domain data at f=160Hz, a total of 2048 discrete data, and perform FFT transformation on it.

[0082]

[0083] in , open Matlab, import the original time domain data, a total of 2048 points, call the fft(X,N) function, and you can get 2048 complex numbers, which are the transformation results of FFT.

[0084] Among them, the vibration measuring instrument is configured as follows: after FFT transformation, the amplitude-frequency curve, i.e., the spectrum, is drawn according to the result; the sampling frequency of the vibration measuring instrument is 25KHz, so the interval of the spectrum curve, i.e., the frequency resolution, is 25000 / 2048, which is rounded to 12, in units of Hz; through the amplitude-frequency curve, it can be obtained that there are pulses greater than the preset value at the 14th and 2034th spectrum lines, and the signal frequency corresponding to the 14th spectrum line is 14 times 12, which is 168Hz.

[0085] In the present application, the vibration measuring instrument embodiment is substantially similar to the compensation method embodiment of the vibration measuring instrument. For related details, please refer to the introduction of the compensation method embodiment of the vibration measuring instrument.

[0086] The embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the compensation method steps of the vibration measuring instrument are implemented. The computer-readable storage medium may include, but is not limited to, any type of disk, including a floppy disk, an optical disk, a DVD, a CD-ROM, a micro drive, and a magneto-optical disk, a ROM, a RAM, an EPROM, an EEPROM, a DRAM, a VRAM, a flash memory device, a magnetic card or an optical card, a nanosystem (including a molecular memory IC), or any type of medium or device suitable for storing instructions and / or data.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A compensation method for a vibration measuring instrument, characterized in that: include: S101, acquiring time domain data, and obtaining spectrum data through FFT transformation; including: Get the original time domain data at f=160Hz, a total of 2048 discrete data, and perform FFT transformation on it. in , open Matlab, import the original time domain data, a total of 2048 points, call the fft(X,N) function, and you can get 2048 complex numbers, which are the transformation results of FFT; S103, plotting an amplitude-frequency curve for analysis according to the FFT transformation result; including: after the FFT transformation, plotting an amplitude-frequency curve, i.e., a spectrum, according to the result; the sampling frequency of the vibration meter is 25KHz, then the interval of the spectrum curve, i.e., the frequency resolution is 25000 / 2048, which is rounded to 12, in units of Hz; through the amplitude-frequency curve, it is obtained that there are pulses greater than a preset value at the 14th and 2034th spectrum lines, and the signal frequency corresponding to the 14th spectrum line is 14 times 12, which is 168Hz; S105, according to the analysis result, correct the corresponding spectrum line; including: in the process of testing the frequency response curve, it is found that when f=160Hz, the effective value measured by the acceleration sensor AD1002 is only 1 / 1.5 of the reference value, therefore, when performing frequency domain compensation, the frequency response curve of the acceleration sensor AD1002 at 160Hz and the spectrum line symmetrical thereto are corrected; S107, recalculating the effective value RMS according to the corrected data; including: According to Parseval's theorem: That is, the energy in the time domain is equal to the energy in its transform domain; The time domain energy is , the frequency domain energy is , Where Ttotal is the total time, P(fn) is the nth power spectrum density value, △f is the FFT frequency interval, Subtract Ttotal from both sides of the equation, and we have , in , N is the block length of FFT, and fs is the sampling frequency.

2. The compensation method of the vibration measuring instrument according to claim 1, characterized in that: Also includes: The velocity and displacement values ​​are calculated by software integration. The velocity, displacement and acceleration are in a first-order and second-order integral relationship.

3. A vibration measuring instrument, characterized in that: The vibration measuring instrument adopts the compensation method of the vibration measuring instrument according to any one of claims 1 to 2, and the vibration measuring instrument is configured as follows: Obtain time domain data and obtain spectrum data through FFT transformation; According to the FFT transformation results, the amplitude-frequency curve is drawn for analysis; after FFT transformation, the amplitude-frequency curve, i.e., the spectrum, is drawn according to the results; the sampling frequency of the vibration meter is 25KHz, so the interval of the spectrum curve, i.e., the frequency resolution is 25000 / 2048, which is rounded to 12, in units of Hz; through the amplitude-frequency curve, it is found that there are pulses greater than the preset value at the 14th and 2034th spectrum lines, and the signal frequency corresponding to the 14th spectrum line is 14 times 12, which is 168Hz; According to the analysis results, the corresponding spectrum lines are corrected; in the process of testing the frequency response curve, it is found that when f=160Hz, the effective value measured by the acceleration sensor AD1002 is only 1 / 1.5 of the reference value. Therefore, when making frequency domain compensation, the 160Hz position of the frequency response curve of the acceleration sensor AD1002 and the spectrum lines symmetrical to it are corrected; Recalculate the effective value RMS based on the corrected data.

4. The vibration measuring instrument according to claim 3, characterized in that: The vibration measuring instrument is configured to obtain the original time domain data at f=160Hz, a total of 2048 discrete data, and perform FFT transformation on them. in , open Matlab, import the original time domain data, a total of 2048 points, call the fft(X,N) function, and you can get 2048 complex numbers, which are the transformation results of FFT.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method described in any one of claims 1 to 2 are implemented.

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