CN111708019A - Engineering structure dynamic characteristic monitoring system based on microwave radar - Google Patents

Engineering structure dynamic characteristic monitoring system based on microwave radar Download PDF

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CN111708019A
CN111708019A CN202010533069.6A CN202010533069A CN111708019A CN 111708019 A CN111708019 A CN 111708019A CN 202010533069 A CN202010533069 A CN 202010533069A CN 111708019 A CN111708019 A CN 111708019A
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frequency
train
vibration
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microwave radar
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CN111708019B (en
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彭志科
李松旭
熊玉勇
任泽生
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Shanghai Jiaotong University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M7/00—Vibration-testing of structures; Shock-testing of structures

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
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  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
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Abstract

A microwave radar-based engineering structure dynamic characteristic monitoring system comprises: the invention has the characteristics of high measurement precision, strong environmental adaptability, wide measuring range, low power consumption and low signal processing complexity.

Description

Engineering structure dynamic characteristic monitoring system based on microwave radar
Technical Field
The invention relates to a technology in the field of structure dynamic characteristic monitoring, in particular to an engineering structure dynamic characteristic monitoring system based on a microwave radar.
Background
With the rapid development of high-speed rails and subways in China in recent years, a large number of elevated roads and bridges are built into communication vehicles, and the structural health monitoring and safety assessment of the civil engineering structure in the service process are concerned and paid more attention.
The dynamic response monitoring of civil engineering structures is mainly embodied in the vibration response monitoring under the excitation of external loads, and generally, vibration measurement techniques and methods can be classified into two main categories, namely contact type and non-contact type. Contact vibration measurement sensors, such as acceleration sensors, dial gauges and strain gauges, are time-consuming and labor-consuming to install and difficult to apply in actual engineering; the non-contact measurement method comprises laser Doppler vibration measurement and a vibration measurement technology based on vision, but the vibration measurement technology and the method based on laser are usually applied to micro-amplitude high-frequency vibration measurement of small structures or surfaces, the requirement on the measurement environment is high, the vibration measurement method based on vision is greatly influenced by light and imaging quality and is limited by the depth of field of a camera, and certain limitation exists in the large-amplitude vibration measurement method.
As a new non-contact vibration and deformation monitoring technology, a vibration measurement technology based on microwave sensing attracts more and more researchers, wherein a vibration measurement method based on a Frequency Modulated Continuous Wave (FMCW) radar has relatively complex microwave signal frequency modulation, high signal processing difficulty, relatively high power consumption and is only suitable for medium and low frequency vibration measurement.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a microwave radar-based engineering structure dynamic characteristic monitoring system which has the characteristics of high measurement precision, strong environmental adaptability, wide range of measurement, low power consumption and low signal processing complexity.
The invention is realized by the following technical scheme:
the invention relates to an engineering structure dynamic characteristic monitoring system based on a Continuous Wave (CW) microwave radar, which comprises: control module and continuous wave microwave radar transceiver, data acquisition and processing module, signal analysis module and demonstration that link to each other respectively with it and save the module, wherein: the continuous wave microwave radar transceiver is used for transmitting radar signals and receiving echo signals to obtain zero intermediate frequency baseband signals of two channels of I/Q and is connected with the data acquisition and processing module and transmits the zero intermediate frequency baseband signals, the data acquisition and processing module extracts vibration displacement time domain information x (t) according to the two-channel zero intermediate frequency baseband signals generated by the continuous wave microwave radar transceiver and outputs the vibration displacement time domain information x (t) to the signal analysis module, the signal analysis module respectively performs spectrum analysis and time-frequency spectrum analysis on the extracted vibration displacement time domain information, extracts inherent frequency of an engineering structure, forced vibration frequency and load effect frequency under different operation conditions and outputs the extracted vibration displacement time domain information to the display and storage module to display and store information including vibration displacement time domain waveforms and vibration characteristic analysis results, and the control module is respectively connected with the continuous wave microwave radar transceiver, The data acquisition and processing module, the signal analysis module and the display and storage module are connected and output to control the start and stop of the system, set the parameters of the continuous wave microwave radar, and control the working operation and data transmission instructions of the modules.
The continuous wave microwave radar transceiver comprises: a transmitting branch consisting of a radio frequency signal source, a power divider, a power amplifier and a transmitting antenna, and a receiving branch consisting of a low-pass filter, a quadrature mixer, a low-noise signal amplifier and a receiving antenna, wherein: the radio frequency signal source is connected with the power divider and transmits a single-frequency carrier signal, one end of the power divider is connected with the power amplifier and transmits the single-frequency carrier signal, the other end of the power divider is connected with the quadrature mixer and transmits a local oscillator signal, the power amplifier is connected with the transmitting antenna and transmits an amplified carrier signal, the receiving antenna is connected with the low-noise amplifier and transmits a receiving signal, the low-noise amplifier is connected with the quadrature mixer and transmits an amplified receiving signal, and the quadrature mixer is connected with the low-pass filter and transmits a down-conversion baseband signal.
The natural frequency of the engineering structure, the forced vibration frequency and the load effect frequency under different operation conditions are obtained through the following steps:
step 1, analyzing free vibration response of the engineering structure after the train is driven away, and obtaining natural frequency f of structural vibration by performing fast Fourier transform on vibration displacement of the train driving-away stage in extracted displacement information x (t)1。
Step 2, analyzing the vibration response to the engineering structure in the running process of the train, performing fast Fourier transform on the train passing stage in the extracted vibration displacement time domain information x (t) to obtain a spectrogram, and calculating the forced vibration according to the train speed v and the train body length LThe theoretical value f of the dynamic frequency is v/L, and the forced vibration frequency f caused by the actual train operation can be obtained by comparing the theoretical value f with the peak value in the spectrogram2. Comparing and analyzing the spectrogram of the structural vibration displacement information in the running process of the train with the spectrogram of the structural vibration displacement after the train drives away, and extracting the load effect frequency f caused by the load effect of the train on the structure3。
And 3, analyzing the influence of the train running speed on the forced vibration frequency, performing short-time Fourier transform on the vibration displacement signal measured in the train running process to obtain a time-frequency spectrogram of the vibration displacement signal, extracting a curve of the forced vibration frequency changing along with time by a ridge line extraction method, and performing inversion to obtain the train running speed and the evolution trend of the forced vibration frequency of the engineering structure.
Technical effects
The invention integrally solves the problems that the installation of a sensor in the traditional contact type measuring method of engineering structures such as bridges is time-consuming and labor-consuming, the laser-based measuring method in the non-contact type measuring method has strict requirements on measuring environment, the vibration measuring method based on vision is greatly influenced by light and imaging quality, the precision is poor, the large-scale measurement is limited, and the frequency modulation continuous wave radar-based measuring method has complex frequency modulation and great signal processing difficulty and is only suitable for medium and low frequency vibration measurement.
Compared with the prior art, the invention realizes non-contact vibration measurement, has high equipment integration level, quick installation and simple and convenient operation; the environmental adaptability is strong, and the transmission of the microwave signals is not influenced by weather and light; the signal processing complexity is low, the measurement precision is high, and the power consumption is low.
Drawings
FIG. 1 is a schematic diagram of a test scenario of the present invention;
FIG. 2 is a block diagram of the system of the present invention;
FIG. 3 is a schematic diagram of a continuous wave microwave radar transceiver according to the present invention;
FIG. 4 is a vibration displacement time-domain waveform diagram of the viaduct structure under the uniform operating condition of the embodiment;
FIG. 5 is a vibration displacement spectrum diagram of the train crossing phase of the viaduct structure under the constant speed operation condition of the embodiment;
FIG. 6 is a vibration displacement frequency spectrum diagram of the train departure phase of the viaduct structure under the constant speed operation condition of the embodiment;
FIG. 7 is a vibration displacement time-domain waveform diagram of the viaduct structure under the accelerated operation condition of the embodiment;
FIG. 8 is a graph of vibration displacement spectra of the overpass structure under accelerated operating conditions of the embodiment;
FIG. 9 is a vibration displacement time-frequency distribution diagram of the viaduct structure under the accelerated operation condition of the embodiment.
Detailed Description
Fig. 1 is a schematic diagram of a test scenario in the present embodiment.
As shown in fig. 2, the engineering structure dynamic response monitoring system based on microwave sensing in this embodiment includes a continuous wave microwave radar transceiver, a data acquisition and processing module, a signal analysis module, a display and storage module, and a control module, where: the continuous wave microwave radar transceiver is connected with the data acquisition and processing module and transmits zero intermediate frequency baseband signals, the data acquisition and processing module respectively performs spectrum analysis and time-frequency spectrum analysis on the extracted vibration displacement time-domain information according to two-channel zero intermediate frequency baseband signals generated by the continuous wave microwave radar transceiver and extracts vibration displacement time-domain information x (t), then outputs the vibration displacement time-domain information to the signal analysis module, the signal analysis module respectively performs spectrum analysis and time-frequency spectrum analysis on the extracted vibration displacement time-domain information, extracts inherent frequency of an engineering structure, forced vibration frequency and load effect frequency under different operation conditions and outputs the extracted forced vibration frequency and load effect frequency to the display and storage module to display and store information including vibration displacement time-domain waveform and vibration characteristic analysis results, and the control module is respectively connected with the continuous wave microwave radar transceiver, the data acquisition and processing module, the signal analysis module and the display and storage module and outputs start and stop of the control, Setting continuous wave microwave radar parameters, and controlling the working operation and data transmission instructions of all modules.
As shown in fig. 3, the continuous wave microwave radar transceiver includes: a transmitting branch consisting of a radio frequency signal source, a power divider, a power amplifier and a transmitting antenna, and a receiving branch consisting of a low-pass filter, a quadrature mixer, a low-noise signal amplifier and a receiving antenna, wherein: the radio frequency signal source is connected with the power divider and transmits a single-frequency carrier signal, one end of the power divider is connected with the power amplifier and transmits the single-frequency carrier signal, the other end of the power divider is connected with the quadrature mixer and transmits a local oscillator signal, the power amplifier is connected with the transmitting antenna and transmits an amplified carrier signal, and the receiving antenna is connected with the low noise amplifier and transmits a receiving signal. The low noise signal amplifier is coupled to the quadrature mixer and transmits the amplified received signal, and the quadrature mixer is coupled to the low pass filter and transmits the down converted baseband signal.
The continuous wave microwave radar transceiver is opposite to the elevated bridge structure to be detected, the transmitting power of the continuous wave microwave radar is set to be 20dBm through the control module, the carrier frequency is set to be 24.26GHz, and meanwhile, the radar is started to work.
The data acquisition and processing module acquires two-channel zero intermediate frequency baseband signals generated by the continuous wave microwave radar transceiver and extracts vibration displacement time domain information. The control data acquisition and processing module acquires radar baseband signals and acquires vibration displacement time-domain waveforms of the viaduct structure, as shown in fig. 4, the vibration displacement time-domain waveforms of the viaduct structure under the condition that two trains run at a constant speed and meet each other.
The control signal analysis module performs spectrum analysis on the measurement result, performs Fourier transform on the vibration displacement of 25-33s sections to obtain a spectrogram, and as shown in FIG. 5, three frequency components of 0.53Hz, 1.07Hz and 4.33Hz can be obviously seen. Considering that the subway train operates to apply periodic excitation load to the structure, the forced vibration frequency generated by the structure is in direct proportion to the operation speed, namely the forced vibration frequency f is equal to v/L, wherein: v is the speed of train operation and L is the train car length. According to the estimation that the train speed is 80km/h and the carriage length is 19.5m, the forced vibration frequency is about 1.14 Hz. Therefore, the forced vibration frequency caused by train operation can be calculated to be 1.07 Hz. By analyzing the free vibration response of the bridge structure in the process of train driving away, as shown in a spectrogram of a section 45-55s shown in fig. 6, the first-order natural frequency of the structure can be clearly identified to be 4.35 Hz. Thus, the remaining 0.53Hz frequency component is the load effect frequency, as analyzed above.
And the control display and storage module is used for displaying and storing analysis results of vibration displacement time domain waveforms, frequency spectrograms, frequency components and the like.
As shown in fig. 7, which is a time-domain waveform diagram of vibration displacement when a train accelerates through an elevated bridge in the implementation process under the scene of the subway acceleration running process in this embodiment, as shown in fig. 8, which is a frequency spectrum diagram obtained through fourier transform, it can be clearly seen that the forced vibration frequency is about 0.31Hz, the load effect frequency is 0.63Hz, and the first-order natural frequency of the viaduct structure is 4.7Hz in the running process of the train. To further analyze the effect of the acceleration process of the train on the vibration response characteristics of the flexible beam structure, a time-frequency distribution graph is obtained by short-time fourier transform, as shown in fig. 9. It can be seen that the frequency of the forced vibration caused by the train operation increases with the increase of the speed, and since the train is accelerated linearly, the frequency of the forced vibration also shows a linear increase.
Through specific practical experiments, by taking the viaduct from the east-chuan road station to the glacier road station of the sea-subway fifth line as an example, the transmitting power of a microwave radar is set to be 20dBm, the carrier frequency is set to be 24.26GHz, vibration displacement time domain information of the viaduct is tested when a train runs at a constant speed, as shown in fig. 4, and fast Fourier transform is performed on a train passing stage and a train running-away stage, as shown in fig. 5 and 6, through analysis, the first-order natural frequency of the viaduct is 4.35Hz, and the load effect frequency is 0.53 Hz. And then, monitoring the vibration displacement of the train in the acceleration stage, as shown in the figure, and performing fast Fourier transform and short-time Fourier transform on the train, so that the first-order natural frequency of the structure in the acceleration stage is 4.7Hz, and the forced vibration frequency can be obviously observed to increase along with the increase of the speed.
Compared with the prior art, the method realizes the accurate extraction of the vibration displacement of the engineering structure by a non-contact vibration measurement method, the error is not more than 20 mu m, the extraction of the dynamic characteristic parameters of the engineering structure under different working conditions is realized, such as the structure natural frequency, the load effect frequency and the forced vibration frequency, the error is not more than 0.1Hz, and the change rule of the forced vibration frequency of the engineering structure along with the train running speed can be presented.
The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (3)

1. An engineering structure dynamic characteristic monitoring system based on continuous wave microwave radar is characterized by comprising: control module and continuous wave microwave radar transceiver, data acquisition and processing module, signal analysis module and demonstration that link to each other respectively with it and save the module, wherein: the continuous wave microwave radar transceiver is used for transmitting radar signals and receiving echo signals to obtain zero intermediate frequency baseband signals of two channels of I/Q and is connected with the data acquisition and processing module and transmits the zero intermediate frequency baseband signals, the data acquisition and processing module extracts vibration displacement time domain information x (t) according to the two-channel zero intermediate frequency baseband signals generated by the continuous wave microwave radar transceiver and outputs the vibration displacement time domain information x (t) to the signal analysis module, the signal analysis module respectively performs spectrum analysis and time-frequency spectrum analysis on the extracted vibration displacement time domain information, extracts inherent frequency of an engineering structure, forced vibration frequency and load effect frequency under different operation conditions and outputs the extracted vibration displacement time domain information to the display and storage module to display and store information including vibration displacement time domain waveforms and vibration characteristic analysis results, and the control module is respectively connected with the continuous wave microwave radar transceiver, The data acquisition and processing module, the signal analysis module and the display and storage module are connected and output to control the start and stop of the system, set the parameters of the continuous wave microwave radar, and control the working operation and data transmission instructions of the modules.
2. The continuous wave microwave radar-based engineering structure dynamic feature monitoring system according to claim 1, wherein the continuous wave microwave radar transceiver comprises: a transmitting branch consisting of a radio frequency signal source, a power divider, a power amplifier and a transmitting antenna, and a receiving branch consisting of a low-pass filter, a quadrature mixer, a low-noise signal amplifier and a receiving antenna, wherein: the radio frequency signal source is connected with the power divider and transmits a single-frequency carrier signal, one end of the power divider is connected with the power amplifier and transmits the single-frequency carrier signal, the other end of the power divider is connected with the quadrature mixer and transmits a local oscillator signal, the power amplifier is connected with the transmitting antenna and transmits an amplified carrier signal, the receiving antenna is connected with the low-noise amplifier and transmits a receiving signal, the low-noise amplifier is connected with the quadrature mixer and transmits an amplified receiving signal, and the quadrature mixer is connected with the low-pass filter and transmits a down-conversion baseband signal.
3. The continuous wave microwave radar-based engineering structure dynamic characteristic monitoring system according to claim 1, wherein the natural frequency of the engineering structure and the forced vibration frequency and the load effect frequency under different operating conditions are obtained by the following steps:
step 1, analyzing free vibration response of the engineering structure after the train is driven away, and obtaining natural frequency f of structural vibration by performing fast Fourier transform on vibration displacement of the train driving-away stage in extracted displacement information x (t)1；
Step 2, analyzing the vibration response to the engineering structure in the running process of the train, performing fast Fourier transform on the train passing stage in the extracted vibration displacement time domain information x (t) to obtain a spectrogram, calculating a theoretical value f of the forced vibration frequency according to the train speed v and the train body length L, and comparing the theoretical value f with the peak value in the spectrogram to obtain the forced vibration frequency f actually caused by train running2(ii) a Comparing and analyzing the spectrogram of the structural vibration displacement information in the running process of the train with the spectrogram of the structural vibration displacement after the train drives away, and extracting the load effect frequency f caused by the load effect of the train on the structure3；
And 3, analyzing the influence of the train running speed on the forced vibration frequency, performing short-time Fourier transform on the vibration displacement signal measured in the train running process to obtain a time-frequency spectrogram of the vibration displacement signal, extracting a curve of the forced vibration frequency changing along with time by a ridge line extraction method, and performing inversion to obtain the train running speed and the evolution trend of the forced vibration frequency of the engineering structure.
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CN112747877A (en) * 2020-10-16 2021-05-04 上海交通大学 Non-contact bridge structure performance and safety rapid test and evaluation system and method
CN116973877A (en) * 2023-09-22 2023-10-31 南京楚航科技有限公司 Millimeter wave radar deformation measurement method, system and measurement truth value calibration method

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CN110031837A (en) * 2019-03-20 2019-07-19 东南大学 A kind of bridge cable group Suo Li synchronous monitoring method and system based on microwave radar
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