Structural vibration monitoring system and method capable of being calibrated on line

Abstract

The invention relates to the technical field of intelligent sensors, and discloses a structural vibration monitoring system and method capable of online calibration, and the system comprises a vibration sensing module which is used for sensing structural vibration and receiving an excitation signal; the data acquisition module is used for converting the analog quantity signal output by the vibration sensing module into a digital quantity signal, transmitting the digital quantity signal to monitoring software and outputting a sine wave signal to the vibration sensing module; the vibration monitoring and calibration software module is used for controlling the data acquisition instrument, receiving data transmitted by the data acquisition instrument, analyzing vibration data and calculating online calibration sensitivity; by accurately controlling a sinusoidal signal input by the self-excitation coil and measuring an output signal of the response coil, sensitivity values of the sensor at different frequencies can be calculated, accurate calibration of the sensitivity of the sensor is realized, and the change of the performance of the sensor can be evaluated by comparing the sensitivity values of the sensor at different time periods. And the accuracy and the reliability of the monitoring data are improved.

Description

Technical Field

[0001] The invention relates to the technical field of intelligent sensors, and in particular to a structural vibration monitoring system and method capable of online calibration. Background Art

[0002] Vibration monitoring devices are important equipment for engineering structural safety monitoring. Existing structural vibration monitoring devices do not have online calibration functions, so they need to be regularly disassembled and sent to the laboratory's vibration table for calibration to determine the current sensitivity of the device. In actual engineering implementation, the disassembly, inspection, and reinstallation of vibration monitoring devices require a lot of manpower, time, and calibration costs, which will significantly increase the operation and maintenance costs of the structural safety monitoring system. Therefore, most of the existing structural vibration monitoring devices have not been calibrated for a long time, resulting in reduced reliability of vibration monitoring data, and thus unable to distinguish whether the safety warning information of the structural vibration safety monitoring device is a false alarm caused by the large test error of the vibration monitoring device itself. For this reason, a structural vibration monitoring system and method that can be calibrated online is proposed. Summary of the invention

[0003] The object of the present invention is to provide a structural vibration monitoring system and method capable of online calibration, so as to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions: a structural vibration monitoring system capable of online calibration, comprising a vibration sensing module, a data acquisition module and a vibration monitoring and calibration software module; The vibration sensing module is used to sense structural vibration and receive excitation signals; The data acquisition module is used to convert the analog signal output by the vibration sensing module into a digital signal and transmit it to the monitoring software, and output a sine wave signal to the vibration sensing module; The vibration monitoring and calibration software module is used to control the data acquisition instrument, receive data transmitted by the data acquisition instrument, analyze vibration data and calculate online calibration sensitivity; The vibration sensing module is connected to the data acquisition module, and the data acquisition module is connected to the vibration monitoring and calibration software module.

[0005] Preferably, the vibration sensing module comprises a shell, a permanent magnet is installed at the inner bottom of the shell, a soft magnet is connected to the top of the permanent magnet, and a coil frame is arranged on the top of the soft magnet.

[0006] Preferably, a self-excitation coil and a response coil are respectively wound around the outer side of the coil frame, the winding directions of the self-excitation coil and the response coil are opposite, and the number of turns of the self-excitation coil is 99-101.

[0007] Preferably, the data acquisition module comprises a data acquisition instrument, and a sinusoidal signal generator is mounted on the surface of the data acquisition instrument.

[0008] Preferably, when the vibration monitoring and calibration software module is calibrated online, the useful sinusoidal signal and amplitude of the calibration response output are accurately extracted from the collected signal, and the sensitivity value is accurately calculated.

[0009] Preferably, the calculation formula of the sinusoidal signal x is:

[0010] Wherein, f is the amplitude and frequency of the excitation sinusoidal signal respectively.

[0011] Preferably, the above-mentioned response output signal calculation formula is:

[0012] Among them, B is the amplitude of the response signal of the sensor response coil only under the excitation of the excitation sinusoidal signal during calibration, and F is the response output signal of the sensor response coil only under the excitation of the structural vibration signal; To reduce the influence of F(t) on the calibration results, you can choose to start the calibration when the structural vibration is small. At this time, the output signal of the sensor is:

[0013] Among them, t is selected as 0≤t≤600 seconds; right Perform smooth transformation to obtain a two-dimensional array of spectrum curves of the signal output by the sensor's response coil .

[0014] Preferably, after the calibration is started, data is collected continuously for 600 seconds, and then FFT smoothing transformation is performed to obtain a two-dimensional array y of the frequency spectrum curve of the signal output by the response coil of the sensor in this time period:

[0015] Wherein, f is the frequency value, y is the spectrum function of y after FFT transformation, x is the spectrum function of x after FFT transformation, and F is the spectrum function of F after FFT transformation; The sampling frequency and acquisition time length are the same, so the f sampling quantization value of the spectrum two-dimensional array obtained twice is the same, that is, the X-axis coordinate value of the spectrum curve obtained twice is the same; Subtract the two obtained spectrum curves. Assuming S is the spectrum function after FFT of the response data of the response coil at the calibration frequency, then:

[0016] because ,so .

[0017] The present invention provides a method for a structural vibration monitoring system capable of online calibration, comprising the following steps: S1. The self-excitation coil and the response coil of the vibration sensing module are both arranged on the coil frame and in the magnetic cylinder of the sensor. The self-excitation coil receives the sinusoidal signal output by the data acquisition module, which is equivalent to the current input into the coil. Then the self-excitation coil forms an Ampere force with the same frequency and amplitude change as the input sinusoidal signal. The Ampere force drives the response coil on the coil frame to move in the magnetic cylinder of the sensor. The response coil moves in the magnetic field to generate an electromotive force and an output voltage signal. The frequency of the output voltage signal is equal to the frequency of the sinusoidal signal input by the self-excitation coil. The amplitude of the output voltage signal is a fixed proportional coefficient to the amplitude of the sinusoidal signal input by the self-excitation coil. This proportional coefficient is the inherent sensitivity value of the sensor. By changing the frequency value of the sinusoidal signal input by the self-excitation coil, the sensitivity value corresponding to different frequency values ​​of the sensor can be obtained. S2, the data acquisition module collects the output voltage signal and converts it into a digital signal and transmits it to the vibration monitoring and calibration software module; S3, the vibration monitoring and calibration software module uses FFT smoothing transformation and spectrum curve subtraction to accurately extract the frequency and amplitude of the sine signal output of the calibration response from the mixed signal, and then calculates the sensitivity value of the sensor at each frequency point. The algorithm of the calculation formula is used to accurately extract the frequency and amplitude of the sine signal output of the calibration response from the mixed signal to calculate the sensitivity value of the sensor; S4. The sensor sensitivity change rate evaluates the error rate of the currently collected vibration data, and then performs calibration to correct the currently collected vibration data.

[0018] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects: By precisely controlling the sinusoidal signal input by the self-excitation coil and measuring the output signal of the response coil, the sensitivity value of the sensor at different frequencies can be calculated, and the precise calibration of the sensor sensitivity can be achieved. By comparing the sensitivity values ​​of the sensor in different time periods, the change in sensor performance can be evaluated, and the collected vibration data can be subsequently calibrated based on the sensitivity change rate, thereby improving the accuracy and reliability of the monitoring data. The system can be calibrated online without the need to remove the vibration sensor from the structure and send it to the laboratory for calibration, which greatly improves the real-time and efficiency of the calibration. The calibration process can be completed through simple operations on the monitoring software on the computer, eliminating the tedious steps of disassembly, inspection, and reinstallation, greatly simplifying the calibration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of module connection of the present invention; Figure 2 It is a schematic diagram of the structure of the vibration sensing sensor of the present invention; Figure 3 It is a circuit schematic diagram of the present invention.

[0021] Explanation of the accompanying reference numerals: 1. coil frame; 2. soft magnet; 3. self-excitation coil; 4. response coil; 5. permanent magnet; 6. housing. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0024] Example See also Figure 1-3 The present invention provides a technical solution: a structural vibration monitoring system that can be calibrated online, including a vibration sensing module, a data acquisition module and a vibration monitoring and calibration software module, the vibration sensing module is connected to the data acquisition module, and the data acquisition module is connected to the vibration monitoring and calibration software module.

[0025] The vibration sensing module is used to sense the structural vibration and receive the excitation signal. The vibration sensing module adds a set of enameled wires to the coil frame 1 of the vibration sensor. The model of the vibration sensor is ZC2000. The vibration sensing module includes a housing 6, a permanent magnet 5 is installed at the bottom of the inner side of the housing 6, a soft magnet 2 is connected to the top of the permanent magnet 5, a coil frame 1 is arranged on the top of the soft magnet 2, and a self-excitation coil 3 and a response coil 4 are respectively wound around the outer side of the coil frame 1. Figure 2 As shown, the winding direction of the self-excitation coil 3 is opposite to that of the response coil 4, the number of turns of the self-excitation coil 3 is 100, and the surface of the self-excitation coil 3 is coated with a three-proof paint for fixing the enameled wire; At the same time, the 2-core BNC connector of the vibration sensor is changed to a 4-core aviation plug, and the two ends of the newly wound enameled wire are welded to the 3rd and 4th cores of the 4-core aviation plug of the sensor to receive the sinusoidal signal output by the data acquisition instrument. The self-excitation coil 3 and the response coil 4 are both on the coil frame 1 of the sensor and in the magnetic cylinder of the sensor; The data acquisition module is used to convert the analog signal output by the vibration sensing module into a digital signal and transmit it to the monitoring software, and output a sine wave signal to the vibration sensing module; The data acquisition module includes a data acquisition instrument, and a sine signal generator is installed on the surface of the data acquisition instrument. The model of the data acquisition instrument is: G01NET-3F. The circuit schematic diagram of the sine signal generator module is as follows: Figure 3 As shown, where: One end of R2 is connected to the RXD pin of U1, and the other end is connected to the U3UART1-TX / A1N5 / PD5 pin; One end of R3 is connected to the TXD pin of U1, and the other end is connected to the U3UART1-RX / A1N6 / PD6 pin The sine signal generator is equipped with a chip, the model of which is AD9833. The sine signal generator is equipped with peripheral capacitors, resistors and power supply circuits. The signal generator has an RS485 communication interface, and its signal output frequency and output stop can be controlled by commands. The data acquisition instrument is equipped with an RS485 communication interface. The signal generator module can be controlled by modifying the underlying program of the data acquisition instrument and through the RS485 communication interface. The signal input terminal of the data acquisition instrument is 8 BNC connectors, which can be changed to 8 4-core aviation plugs. The 1-core of the 4-core aviation plug is connected to the signal acquisition channel of the acquisition card, the 2-core is connected to the signal ground wire of the acquisition card, the 3-core is connected to the positive pole of the signal generator output, and the 4-core is connected to the negative pole of the signal generator output. Vibration monitoring and calibration software module, used to control the data acquisition instrument, receive data transmitted by the data acquisition instrument, analyze vibration data and calculate online calibration sensitivity; The vibration monitoring and calibration software module is secondary developed based on the vibration monitoring software to add calibration function. The vibration monitoring software is G01NET-FDC. When the vibration monitoring and calibration software module is calibrated online, the useful calibration response output sinusoidal signal and amplitude are accurately extracted from the collected signal, and the sensitivity value is accurately calculated. When the vibration monitoring system is calibrated online, it is not only stimulated by the sinusoidal signal output by the data acquisition instrument, but also by the structural vibration of the sensor fixed position.

[0026] The calculation formula of sinusoidal signal xt is:

[0027] Wherein, f is the amplitude and frequency of the excitation sinusoidal signal respectively.

[0028] Assuming that the sensor response coil responds to the output signal under the common excitation of the calibration excitation sinusoidal signal and the structural vibration signal during calibration, the calculation formula of the response output signal is:

[0029] Among them, B is the amplitude of the response signal of the sensor response coil only under the excitation of the excitation sinusoidal signal during calibration, and Ft is the response output signal of the sensor response coil only under the excitation of the structural vibration signal. Because the structural vibration signal is a random vibration signal, it may contain a prominent signal with the same frequency value as the excitation sinusoidal signal. If the influence of F(t) is not reduced, the sensitivity deviation of the online calibration will be large; In order to reduce the impact of F(t) on the calibration results, you can choose to start the calibration when the structural vibration is small. For example, if the monitoring object is a bridge beam, the online calibration of the vibration monitoring system can be performed when the wind speed is low and no vehicles pass by. In this case, the frequency of the structural vibration is mainly a plurality of natural frequency value signals, and the amplitude is relatively stable, and the F(t) signal at this time is relatively stable, reducing the impact of F(t) on the calibration results. You can choose to start the calibration when the structural vibration is small. At this time, the output signal of the sensor is:

[0030] Among them, t is selected as 0≤t≤600 seconds; right Perform smooth transformation to obtain a two-dimensional array of the spectrum curve of the signal output by the sensor's response coil during this time period .

[0031] After calibration is turned on, data is collected continuously for 600 seconds, and then FFT smoothing transformation is performed to obtain the two-dimensional array yf of the spectrum curve of the signal output by the sensor's response coil during this period:

[0032] Wherein, f is the frequency value, yf is the spectrum function of yt after FFT transformation, xf is the spectrum function of xt after FFT transformation, and Ff is the spectrum function of Ft after FFT transformation; The sampling frequency and acquisition time length are the same, so the f sampling quantization value of the spectrum two-dimensional array obtained twice is the same, that is, the X-axis coordinate value of the spectrum curve obtained twice is the same; Subtract the two obtained spectrum curves. Assuming that Sf is the spectrum function after FFT of the response data of the response coil at the calibration frequency, then:

[0033] because ,so ; During calibration, since the frequency and amplitude of the excitation sinusoidal signal are set by the monitoring software through commands and are known parameter values, the frequency value and amplitude A of the excitation sinusoidal signal are known, so they can be obtained through a two-dimensional array. Obtain the response amplitude value B corresponding to the frequency of the excitation sinusoidal signal. Based on the above method, the response amplitude B and frequency value of the sensor's response coil under the excitation of the excitation sinusoidal signal are obtained. B divided by A is the sensitivity value of the sensor at this frequency value.

[0034] Repeating the above method, the sensor sensitivity values ​​corresponding to multiple frequency values ​​can be obtained. By comparing the sensitivity values ​​with the initial sensitivity values ​​of the sensor, the sensitivity change rate of the sensor corresponding to each frequency value can be obtained. Based on the change rate, the error rate of the currently collected vibration data can be evaluated, and based on this error rate and subsequent calibration of the currently collected vibration data.

[0035] For example: if the sensitivity of a sensor decreases by 10% at each frequency point, the currently collected vibration data can be divided by a coefficient of 0.9 to restore the currently collected vibration data to a normal value. Compared with the existing structural vibration monitoring system that needs to be regularly disassembled and sent to the laboratory for calibration on a vibration table, the structural vibration monitoring system of the present invention does not need to be disassembled and can be calibrated with simple operations on a computer, thereby eliminating the tedious work of disassembling, inspecting, and reinstalling the vibration monitoring system, improving the convenience of the structural vibration monitoring system calibration, and reducing the calibration cost of the structural vibration monitoring system.

[0036] The present invention also provides a method for an online calibrated structural vibration monitoring system, comprising the following steps: S1, the self-excitation coil 3 and the response coil 4 of the vibration sensing module are both arranged on the coil frame 1 and in the magnetic cylinder of the sensor. The self-excitation coil 3 receives the sinusoidal signal output by the data acquisition module, which is equivalent to the current input into the coil, and then the self-excitation coil forms an Ampere force with the same frequency and amplitude change as the input sinusoidal signal. The Ampere force drives the response coil 4 on the coil frame 1 to move in the magnetic cylinder of the sensor. The response coil 4 moves in the magnetic field to generate an electromotive force and an output voltage signal. The frequency of the output voltage signal is equal to the frequency of the sinusoidal signal input by the self-excitation coil 3, and the amplitude of the output voltage signal is a fixed proportional coefficient to the amplitude of the sinusoidal signal input by the self-excitation coil 3. This proportional coefficient is the inherent sensitivity value of the sensor. By changing the frequency value of the sinusoidal signal input by the self-excitation coil 3, the sensitivity value corresponding to different frequency values ​​of the sensor can be obtained; S2, the data acquisition module collects the output voltage signal and converts it into a digital signal and transmits it to the vibration monitoring and calibration software module; S3, the vibration monitoring and calibration software module uses FFT smoothing transformation and spectrum curve subtraction to accurately extract the frequency and amplitude of the sine signal output of the calibration response from the mixed signal, and then calculates the sensitivity value of the sensor at each frequency point. The algorithm of the calculation formula is used to accurately extract the frequency and amplitude of the sine signal output of the calibration response from the mixed signal to calculate the sensitivity value of the sensor; S4. The sensor sensitivity change rate evaluates the error rate of the currently collected vibration data, and then performs calibration to correct the currently collected vibration data.

[0037] In summary, by precisely controlling the sinusoidal signal input by the self-excitation coil and measuring the output signal of the response coil, the sensitivity value of the sensor at different frequencies can be calculated, and the precise calibration of the sensor sensitivity can be achieved. By comparing the sensitivity values ​​of the sensor in different time periods, the change in sensor performance can be evaluated, and the collected vibration data can be subsequently calibrated based on the sensitivity change rate, thereby improving the accuracy and reliability of the monitoring data. The system can be calibrated online without the need to remove the vibration sensor from the structure and send it to the laboratory for calibration, which greatly improves the real-time and efficiency of the calibration. The calibration process can be completed through simple operations on the monitoring software on the computer, eliminating the tedious steps of disassembly, inspection, and reinstallation, greatly simplifying the calibration process.

[0038] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways, even if such combinations and / or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All of these combinations and / or combinations fall within the scope of the present invention.

Claims

1. A structural vibration monitoring system capable of online calibration, characterized in that: It includes vibration sensing module, data acquisition module and vibration monitoring and calibration software module; The vibration sensing module is used to sense structural vibration and receive excitation signals; The data acquisition module is used to convert the analog signal output by the vibration sensing module into a digital signal and transmit it to the monitoring software, and output a sine wave signal to the vibration sensing module; The vibration monitoring and calibration software module is used to control the data acquisition instrument, receive data transmitted by the data acquisition instrument, analyze vibration data and calculate online calibration sensitivity; The vibration sensing module is connected to the data acquisition module, and the data acquisition module is connected to the vibration monitoring and calibration software module.

2. The structural vibration monitoring system capable of online calibration according to claim 1, characterized in that: The vibration sensing module comprises a housing (6), a permanent magnet (5) is mounted on the bottom inner side of the housing (6), a soft magnet (2) is connected to the top of the permanent magnet (5), and a coil frame (1) is arranged on the top of the soft magnet (2).

3. The structural vibration monitoring system capable of online calibration according to claim 2, characterized in that: A self-excitation coil (3) and a response coil (4) are respectively wound around the outside of the coil frame (1); the winding directions of the self-excitation coil (3) and the response coil (4) are opposite; and the number of turns of the self-excitation coil (3) is 99-101.

4. The structural vibration monitoring system capable of online calibration according to claim 1, characterized in that: The data acquisition module comprises a data acquisition instrument, and a sine signal generator is installed on the surface of the data acquisition instrument.

5. The structural vibration monitoring system capable of online calibration according to claim 1, characterized in that: When the vibration monitoring and calibration software module is calibrated online, the useful sine signal and amplitude of the calibration response output are accurately extracted from the collected signal, and the sensitivity value is accurately calculated.

6. The structural vibration monitoring system capable of online calibration according to claim 5, characterized in that: The calculation formula of the sinusoidal signal x(t) is: Wherein, f is the amplitude and frequency of the excitation sinusoidal signal respectively.

7. The structural vibration monitoring system capable of online calibration according to claim 6, characterized in that: The response output signal calculation formula is: Wherein, B is the amplitude of the response signal of the sensor response coil only under the excitation of the excitation sinusoidal signal during calibration, and F(t) is the response output signal of the sensor response coil only under the excitation of the structural vibration signal; To reduce the influence of F(t) on the calibration results, you can choose to start the calibration when the structural vibration is small. At this time, the output signal of the sensor is: Among them, t is selected as 0≤t≤600 seconds; right Perform smooth transformation to obtain a two-dimensional array of spectrum curves of the signal output by the sensor's response coil .

8. The structural vibration monitoring system capable of online calibration according to claim 7, characterized in that: After the calibration is started, data is collected continuously for 600 seconds, and then FFT smoothing transformation is performed to obtain the two-dimensional array y (f) of the spectrum curve of the signal output by the sensor response coil in this time period: Wherein, f is the frequency value, y(f) is the spectrum function of y(t) after FFT transformation, x(f) is the spectrum function of x(t) after FFT transformation, and F(f) is the spectrum function of F(t) after FFT transformation; The sampling frequency and acquisition time length are the same, so the f sampling quantization value of the spectrum two-dimensional array obtained twice is the same, that is, the X-axis coordinate value of the spectrum curve obtained twice is the same; Subtract the two obtained spectrum curves. Assuming that S(f) is the spectrum function after FFT of the response data of the response coil at the calibration frequency, then: because ,so .

9. A method for an online calibrated structural vibration monitoring system according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, the self-excitation coil (3) and the response coil (4) of the vibration sensing module are both arranged on the coil frame (1) and in the magnetic cylinder of the sensor. The self-excitation coil (3) receives the sinusoidal signal output by the data acquisition module, which is equivalent to the current input into the coil. Then, the self-excitation coil forms an Ampere force with the same frequency and amplitude change as the input sinusoidal signal. The Ampere force drives the response coil (4) on the coil frame (1) to move in the magnetic cylinder of the sensor. The response coil (4) moves in the magnetic field to generate an electromotive force and an output voltage signal. The frequency of the output voltage signal is equal to the frequency of the sinusoidal signal input by the self-excitation coil (3). The amplitude of the output voltage signal is a fixed proportional coefficient to the amplitude of the sinusoidal signal input by the self-excitation coil (3). This proportional coefficient is the inherent sensitivity value of the sensor. By changing the frequency value of the sinusoidal signal input by the self-excitation coil (3), the sensitivity value corresponding to different frequency values ​​of the sensor can be obtained; S2, the data acquisition module collects the output voltage signal and converts it into a digital signal and transmits it to the vibration monitoring and calibration software module; S3, the vibration monitoring and calibration software module uses FFT smoothing transformation and spectrum curve subtraction to accurately extract the frequency and amplitude of the sine signal output of the calibration response from the mixed signal, and then calculates the sensitivity value of the sensor at each frequency point. The algorithm of the calculation formula is used to accurately extract the frequency and amplitude of the sine signal output of the calibration response from the mixed signal to calculate the sensitivity value of the sensor; S4. The sensor sensitivity change rate evaluates the error rate of the currently collected vibration data, and then performs calibration to correct the currently collected vibration data.

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