CN112816977A - Dome structure health monitoring method and system based on microwave radar - Google Patents

Dome structure health monitoring method and system based on microwave radar Download PDF

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CN112816977A
CN112816977A CN202011118617.5A CN202011118617A CN112816977A CN 112816977 A CN112816977 A CN 112816977A CN 202011118617 A CN202011118617 A CN 202011118617A CN 112816977 A CN112816977 A CN 112816977A
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dome structure
monitoring
deformation
health monitoring
dome
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CN112816977B (en
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熊玉勇
彭志科
李松旭
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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
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

The invention provides a dome structure health monitoring and evaluating method and system based on a microwave radar, which comprises the following steps: transmitting and receiving linear frequency modulation continuous wave microwave signals to a dome structure to be detected through a microwave radar, and synchronously acquiring multi-channel intermediate frequency baseband signals output by the microwave radar; obtaining a distance-angle image thermal map of the dome structure to be measured, positioning key measuring points of the dome structure from the combined dimension of the distance and the angle, and extracting vibration displacement time domain information of each measuring point; extracting characteristic parameters of each composition structure of the dome structure to be detected under static and dynamic loads through cable force monitoring, deformation monitoring and vibration monitoring; and according to the characteristic parameters of each composition structure of the dome structure to be detected under static and dynamic loads, performing health monitoring and safety evaluation on the dome structure through multi-characteristic fusion analysis. The full-field non-contact monitoring technology and method with high efficiency, easy operation, low cost and high reliability are provided for the health monitoring of the dome structure.

Description

Dome structure health monitoring method and system based on microwave radar
Technical Field
The invention relates to the technical field of structural health monitoring, in particular to a dome structure health monitoring and safety assessment method and system based on a microwave radar.
Background
With the rapid development of the research of the large-span chord support structure, the structure is widely applied to the dome design of buildings such as high-speed railway stations, large stadiums, exhibition halls and the like. The dome with the chord structure is used more as a novel composite structure with good flexibility and rigidity, the combination of the latticed shell and the cable structure improves the whole latticed shell in the aspects of stress and strength, and the whole stability of the structure is improved. However, due to the fact that high-speed trains enter the station, wind load, earthquake, temperature, deformation of underground structures and the like, material aging, fatigue and fracture are inevitably generated, and safety of the dome structure is affected, and therefore the dome structure health monitoring and evaluation has important engineering value and practical significance.
The vibration test is a mainstream method for monitoring the structural health at present, wherein in contact type vibration measurement, a fiber grating sensor and an acceleration sensor need to be installed on a dome structure, but the problems of too many sensors, too long connecting wires between the sensors, complex network distribution and the like exist, a large amount of manpower and material resources are needed, and the test cost is high; the laser vibrometer in the non-contact sensor can better solve the problem that the contact sensor is complex and complicated to install, but the measuring method can only be applied to single-point measurement, and a plurality of laser displacement sensors need to be arranged or a scanning mode needs to be used for testing when the structural health of the whole dome structure is monitored; in addition, the vision-based vibration measurement method can realize non-contact dome structure full-field vibration measurement, but the vision-based vibration measurement method is greatly influenced by the measurement environment and the imaging quality, the measurement precision is low, and the complexity of video signal processing is high.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a dome structure health monitoring and evaluating method and system based on a microwave radar.
The invention provides a dome structure health monitoring and safety assessment method based on a microwave radar, which comprises the following steps:
step 1: transmitting and receiving a linear frequency modulation continuous wave microwave signal to a dome structure to be detected to generate a multi-channel intermediate frequency baseband signal;
step 2: obtaining a distance-angle image thermal map of the dome structure to be measured according to the multi-channel intermediate frequency baseband signal, positioning key measuring points of the dome structure from the combined dimension of distance and angle, and synchronously extracting deformation and vibration displacement time domain information of each key measuring point;
and step 3: according to the deformation and vibration displacement time domain information of each measuring point, extracting characteristic parameters of each composition structure of the dome structure to be measured under static and dynamic loads through cable force monitoring, deformation monitoring and vibration monitoring;
and 4, step 4: and according to the characteristic parameters of each composition structure of the dome structure to be detected under static and dynamic loads, performing health monitoring and safety evaluation on the dome structure through multi-characteristic fusion analysis.
Preferably, the step 2 includes:
step 2.1, selecting a multichannel intermediate frequency baseband signal of a certain sweep frequency period, obtaining a distance-angle image thermal image of the dome structure through two-dimensional fast Fourier transform, and positioning a full-field measuring point of the dome structure;
step 2.2, estimating phase evolution information of the key measuring point of the dome structure in each sweep frequency period, wherein the estimation method comprises the following steps:
Figure BDA0002731199100000021
Figure RE-GDA0002807103880000022
indicates that the position information is (k)q,pq) Q1, 2.. Q. the phase information of the Q measuring point of the dome structure in the i transmitting period, kqAnd pqDistance dimension index and angle dimension index of the distance-angle image thermal image matrix corresponding to the qth measuring point, T is the repeated emission period of the linear frequency modulation signal, arg [ ·]For taking complex phase operations, si(. h) is the ith transmit period multi-channel IF baseband signal matrix, NfftDiscrete number of points, M, for fast Fourier transform in step 2.1 along each channel directionfftDiscrete points of fast Fourier change along the multi-channel direction in the step 2.1 are counted, M is the equivalent number of receiving channels, N is the discrete points of the intermediate frequency baseband signal of each channel in a single transmitting period, j is an imaginary number unit, e is an exponential form, and pi is a circumferential rate;
step 2.3, extracting deformation and vibration displacement time domain information:
Figure BDA0002731199100000023
λcis the wavelength corresponding to the center frequency of the carrier wave of the linear frequency modulation continuous wave,
Figure BDA0002731199100000024
is composed of
Figure BDA0002731199100000025
Average of (d), phiqThe included angle between the deformation of the qth measuring point and the vibration direction and the radar sight line direction is shown.
And x (q, iT) is a deformation and vibration displacement extraction value of the qth measuring point in the ith emission period.
Preferably, said step 2.1 comprises:
firstly, fast Fourier transform is carried out on the medium-frequency baseband signals of the single sweep frequency period and the multiple channels along each channel direction to obtain distance dimension information of the dome structure to be tested, then fast Fourier transform is carried out again along the multiple channels to obtain angle dimension information of the dome structure, and therefore joint full-field positioning of the dome structure in the distance dimension and the angle dimension is achieved.
Preferably, the step 3 comprises:
step 3.1, cable force monitoring, namely performing frequency spectrum analysis on the cable vibration displacement time domain information measured in the step 2.3, and extracting the first-order natural frequency f of the measured cable vibrationpAnd is based on the cable force of the cable and the first order inherent property of the cableThe mathematical relationship of the frequency is to calculate the magnitude of the cable force as:
Figure BDA0002731199100000031
Fpp is the linear density of the cable, and L is the cable force of the P-th cable in the monitoring rangepThe length of the p-th inhaul cable is shown;
3.2, monitoring deformation, namely extracting the displacement deformation quantity of the steel rod type structure in the dome structure under the action of static load through the step 2.3;
and 3.3, vibration monitoring, namely monitoring vibration displacement time domain information of the dome steel rod structure under natural excitation, and identifying modal parameters of the structure through modal analysis.
Preferably, the step 4 comprises:
performing multi-feature fusion analysis on the characteristic parameters of the dome structure extracted in the step 3 under the static and dynamic loads through experience analogy, theoretical analysis and specification requirements, and performing health monitoring and safety evaluation on the dome structure;
the criteria for the security assessment include: whether the cable force of the stay cable exceeds the bearing limit of the stay cable, whether the deformation of the steel rod type structure exceeds the design range under the action of load, and whether the natural frequency of the structure exceeds the threshold range and the change of the mode vibration type due to fatigue or damage.
The invention provides a dome structure health monitoring and safety evaluation system based on a microwave radar, which comprises:
a microwave radar module: transmitting and receiving a linear frequency modulation continuous wave microwave signal to a dome structure to be detected to generate a multi-channel intermediate frequency baseband signal;
the signal acquisition and processing module: calculating to obtain a distance-angle image thermal map of the dome structure to be measured according to the multi-channel intermediate frequency baseband signal, positioning the dome structure full-field measuring points from the distance-angle combined dimension, and synchronously extracting deformation and vibration displacement time domain information of each key measuring point;
a signal analysis module: according to deformation and vibration displacement time domain information of each measuring point, characteristic parameters of each composition structure of the dome structure to be measured under static and dynamic loads are extracted through cable force monitoring, deformation monitoring and vibration monitoring, and health monitoring and safety assessment are carried out on the dome structure through multi-characteristic fusion analysis.
Preferably, the microwave radar module includes: the device comprises a linear frequency modulation continuous wave microwave signal source, a power divider, a power amplifier, a low noise amplifier, a frequency mixer, a low pass filter, a transmitting antenna and a receiving antenna;
preferably, the number of the transmitting antennas is one or more, and a linear frequency modulation continuous wave microwave signal transmitted by the transmitting antennas covers the dome structure to be tested;
the number of the receiving antennas is multiple, and the receiving antennas are distributed in a linear equal-spacing array.
Preferably, the method further comprises the following steps:
the display and early warning module: and displaying the distance-angle image thermal image of the dome structure and deformation and vibration displacement time domain information of each measuring point obtained by the signal acquisition and processing module, sending early warning according to the results of health monitoring and safety evaluation by the signal analysis module and the results of health monitoring and safety evaluation, and storing the output results of the microwave radar module, the signal acquisition and processing module and the signal analysis module as required.
Compared with the prior art, the invention has the following beneficial effects:
1. the method has the advantages that the deformation and vibration displacement time domain information of the dome structure full-field measuring points can be reliably distinguished and synchronously extracted through distance and angle dimension combined sensing by utilizing a single-transmitting multi-receiving or multi-transmitting multi-receiving microwave radar mode, the problems of static clutter interference, adjacent multi-component coupling, same distance unit component aliasing interference and the like caused by structural complexity such as rod pieces formed by the dome structure are effectively inhibited, high-precision monitoring of the full-field multi-measuring point deformation and vibration displacement information is realized, characteristic information is extracted, health monitoring and evaluation are carried out on the dome structure through a multi-characteristic fusion method, the problem of insufficient characteristic information existing in single-characteristic evaluation is solved, and the evaluation reliability is greatly improved.
2. The technology of the invention can realize deformation and vibration monitoring of all-field multi-target or multi-measuring-point, non-contact, remote, high-precision, all-weather dome structure multi-component all-day, and has simple operation and lower cost.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic view of the present invention for performing dome structure health monitoring;
FIG. 2 is a flow chart of the operation of the present invention;
FIG. 3 is a schematic diagram of the instantaneous frequency of the LFMCW radar transmitting signal and the receiving signal of the present invention;
FIG. 4 is a block diagram of a health monitoring and safety evaluation system for a dome structure based on microwave sensing according to the present invention;
fig. 5 is a schematic structural diagram of a microwave radar module according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
Example 1
Fig. 1 is a schematic diagram of dome structure health monitoring and safety evaluation method and system based on microwave radar according to the present invention. A single microwave radar or a plurality of microwave radars can be used for monitoring according to the size of the dome structure and the test requirements.
The method for monitoring the health and evaluating the safety of the dome structure based on the microwave radar is shown in fig. 2 and comprises the following steps:
step 1, installing a microwave radar system and adjusting the beam direction of an antenna to enable the beam to cover a dome to be detectedA top structure for transmitting and receiving Linear Frequency Modulated Continuous Wave (LFMCW) microwave signals, synchronously acquiring multi-channel intermediate frequency baseband signals, as shown in FIG. 3, and transmitting the signals by three transmitting antennas in a time-sharing manner, and simultaneously receiving instantaneous frequency diagrams of the microwave signals by four receiving antennas, wherein the frequency sweep period is T, and the signal transmission period is TfThe bandwidth is B and the received signal is the time delay of the transmitted signal.
Step 2, obtaining a distance-angle image thermal map of the dome structure to be measured according to the multi-channel intermediate frequency baseband signal, positioning key measuring points of the dome structure from the combined dimension of the distance and the angle, and synchronously extracting deformation and vibration displacement time domain information of each measuring point;
step 3, extracting characteristic parameters of each composition structure of the dome structure to be detected under static and dynamic loads through cable force monitoring, deformation monitoring and vibration monitoring according to deformation and vibration displacement time domain information of each measuring point;
and 4, carrying out health monitoring, safety assessment and early warning on the dome structure through multi-feature fusion analysis according to the feature parameters of each composition structure of the dome structure to be tested under static and dynamic loads.
The method for positioning each measuring point of the dome and extracting vibration displacement time domain information through the distance-angle image thermal image in the step 2 comprises the following steps:
and 2.1, selecting a multichannel intermediate frequency baseband signal of a certain frequency sweep period, obtaining a distance-angle image thermal image of the dome structure through two-dimensional fast Fourier transform, and positioning the full-field measuring point of the dome structure. Firstly, fast Fourier transform is carried out on the medium-frequency baseband signals of the single sweep frequency period and the multiple channels along each channel direction to obtain distance image information of the dome structure to be detected, then fast Fourier transform is carried out again along the multiple channels to obtain angle image information of the dome structure, and therefore joint positioning and distinguishing of the dome structure in the distance dimension and the angle dimension are achieved.
And 2.2, determining a key area for structure monitoring through dynamic characteristic analysis of the reticulated shell structure, and extracting phase evolution information of key measuring points of the dome structure in each sweep frequency period. According to the interference phase modulation principle of deformation and vibration of each measuring point on a multi-channel baseband signal and the principle of phase difference (namely d sin theta/lambda, d is the interval of multiple receiving antennas, lambda is the carrier wavelength, and theta is the incident angle of a target or measuring point) with a specific relationship among multiple channels, the interference phase evolution caused by vibration of the measuring points in the whole field can be equivalently transferred from a distance dimension to an angle dimension through derivation and analysis. Therefore, in order to inhibit the influence of the dome complex structure and the measuring points on the serious adjacent component coupling interference and the same-distance unit component aliasing interference brought by the microwave deformation and vibration measurement and obtain the high-precision deformation and vibration information extraction result, the distance-angle joint dimension full-field measuring point interference phase evolution estimation is adopted, and the estimation method comprises the following steps:
Figure BDA0002731199100000061
Figure RE-GDA0002807103880000062
indicates that the position information is (k)q,pq) Q1, 2.. Q. the phase information of the Q measuring point of the dome structure in the i transmitting period, kqAnd pqDistance dimension index and angle dimension index of the distance-angle image thermal image matrix corresponding to the qth measuring point, T is the repeated emission period of the linear frequency modulation signal, arg [ ·]For taking complex phase operations, si(. h) is the ith transmit period multi-channel IF baseband signal matrix, NfftDiscrete number of points, M, for fast Fourier transform in step 2.1 along each channel directionfftThe number of discrete points for performing fast fourier transform in the multi-channel direction in step 2.1, M is the equivalent number of receiving channels, N is the number of discrete points of the intermediate frequency baseband signal of each channel in a single transmission period, and j is an imaginary unit;
step 2.3, extracting deformation and vibration displacement time domain information:
Figure BDA0002731199100000063
λcis the wavelength corresponding to the center frequency of the carrier wave of the linear frequency modulation continuous wave,
Figure BDA0002731199100000064
is composed of
Figure BDA0002731199100000065
Average of (d), phiqThe included angle between the deformation of the qth measuring point and the vibration direction and the radar sight line direction is shown.
And x (q, iT) is a deformation and vibration displacement extraction value of the qth measuring point in the ith emission period.
The characteristic parameter method of each dome component structure in the step 3 under static and dynamic loads comprises the following steps:
and 3.1, monitoring the cable force. The stay cable is a key force-bearing part in the dome structure, and breakage, corrosion and failure of the stay cable play an important role in the stability and safety of the dome structure, so that real-time monitoring of the cable force is necessary. Carrying out frequency spectrum analysis including fast Fourier transform on the inhaul cable vibration displacement time domain information measured in the step 2.3, and detecting the first-order natural frequency f of inhaul cable vibrationpAnd according to the mathematical relationship between the cable force of the stay cable and the first-order natural frequency of the stay cable, the cable force is obtained as follows:
Figure BDA0002731199100000071
in the formula, FpIn order to monitor the cable force of the P (1,2, …, P) th cable in the range, ρ is the linear density of the cable, LpIs the length of the p-th cable.
And 3.2, monitoring deformation. And (3) extracting displacement deformation quantities of steel rod structures such as the dome chord, the stay bar and the connecting rod under the action of static load through the step 2.3.
And 3.3, monitoring vibration. Vibration displacement time domain information of the dome steel rod structure under natural excitation of wind load, ground movement and the like is monitored, and modal parameters of the structure, including inherent frequency, modal vibration mode and damping ratio of each order, are identified through modal analysis.
The method for carrying out structure health monitoring, safety assessment and early warning on the dome in the step 4 comprises the following steps:
and 3, performing multi-feature fusion analysis on the characteristic parameters of the dome structure under the static and dynamic loads through empirical analogy, theoretical analysis and specification requirements, and performing health and safety evaluation on the dome structure, wherein the evaluation criterion is as follows: whether the cable force of the stay cable exceeds the bearing limit of the stay cable, whether the deformation of the steel rod type structure exceeds the design range under the action of load, and whether the natural frequency of the structure exceeds the threshold range and the change of the mode vibration type due to fatigue or damage. When the monitoring result exceeds the safety threshold range, the early warning system gives an alarm and indicates the specific structure of the fault and the damage so as to solve and process in time.
Example 2
The health monitoring and safety evaluation system for the dome structure based on microwave sensing, as shown in fig. 4, includes: the system comprises a microwave radar module, a signal acquisition and processing module, a signal analysis module and an early warning module.
The microwave radar module, as shown in fig. 5, includes:
the device comprises a linear frequency modulation continuous wave microwave signal source, a power divider, a power amplifier, a low noise amplifier, a mixer, a low pass filter, a transmitting antenna and a receiving antenna. The number of the power divider and the power amplifier is the same as that of the transmitting antennas, and the number of the low noise amplifier is the same as that of the receiving antennas.
The number of the transmitting antennas is one or more; the number of the receiving antennas is multiple, the receiving antennas are distributed in a linear equal-spacing array, and preferably, the spacing is smaller than or equal to half of the carrier wavelength of the transmitted microwave signals.
The FMCW microwave signal source is connected with the power divider to transmit a linear frequency modulation carrier signal, one end of the power divider is connected with the power amplifier, and the other end of the power divider is connected with the frequency mixer and transmits a local oscillator signal; the power amplifier is connected with the transmitting antenna and transmits amplified linear frequency modulation carrier signals, the receiving antenna is connected with the low noise amplifier, the low noise amplifier is connected with the frequency mixer and transmits the amplified receiving signals, and the output end of the frequency mixer is connected with the low pass filter and generates down-conversion baseband signals.
The FMCW microwave signal source is divided into two paths through the power divider, one path of the FMCW microwave signal source is connected with the transmitting antenna through the power amplifier and is transmitted by the transmitting antenna, and the other path of the FMCW microwave signal source and the amplified receiving signal generate a mixing signal through a mixer.
The receiving antenna receives microwave signals reflected by the inhaul cable and transmits the microwave signals to the frequency mixer through the low-noise amplifier; the mixer mixes the microwave signal transmitted by the low noise amplifier with the other path of microwave signal after passing through the power divider, and outputs a multi-channel baseband signal after being processed by the low pass filter.
The signal acquisition and processing module: the system is used for synchronously acquiring multi-channel baseband signals output by the microwave radar module, positioning each measuring point of the dome structure through distance-angle joint dimensionality and extracting deformation and vibration displacement time domain information. In order to utilize the phase difference information between multiple channels, the multi-channel baseband signals need to be synchronously acquired.
A signal analysis module: according to deformation and vibration displacement time domain information of each measuring point, characteristic parameters of each composition structure of the dome structure to be measured under static and dynamic loads are extracted through cable force monitoring, deformation monitoring and vibration monitoring, and health conditions and safety performance evaluation results of the dome structure are judged through multi-characteristic fusion analysis.
The early warning module: displaying the distance-angle image thermal map of the dome structure and the deformation and vibration displacement time domain information of each measuring point obtained by the signal acquisition and processing module, and the information including the characteristic parameters and the structural health and safety evaluation results obtained by the signal analysis module, sending out early warning according to the health monitoring and safety evaluation results, and storing the output results of the microwave radar module, the signal acquisition and processing module and the signal analysis module as required.
The microwave radar module is connected with the signal acquisition and processing module and transmits a multi-channel baseband signal, the signal acquisition and processing module is connected with the signal analysis module and transmits vibration displacement time domain information of each measuring point, and the signal analysis module is connected with the early warning module and transmits structural characteristic parameters and a health assessment result.
Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, units provided by the present invention as pure computer readable program code, the system and its various devices, modules, units provided by the present invention can be fully implemented by logically programming method steps in such a manner as to implement the same functions in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system and various devices, modules and units thereof provided by the invention can be regarded as a hardware component, and the devices, modules and units included in the system for realizing various functions can also be regarded as structures in the hardware component; means, modules, units for performing the various functions may also be regarded as structures within both software modules and hardware components for performing the method.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims (9)

1. A dome structure health monitoring and safety assessment method based on a microwave radar is characterized by comprising the following steps:
step 1: transmitting and receiving a linear frequency modulation continuous wave microwave signal to a dome structure to be detected to generate a multi-channel intermediate frequency baseband signal;
step 2: obtaining a distance-angle image thermal map of the dome structure to be measured according to the multi-channel intermediate frequency baseband signal, positioning key measuring points of the dome structure from the combined dimension of distance and angle, and synchronously extracting deformation and vibration displacement time domain information of each key measuring point;
and step 3: according to the deformation and vibration displacement time domain information of each measuring point, extracting characteristic parameters of each composition structure of the dome structure to be measured under static and dynamic loads through cable force monitoring, deformation monitoring and vibration monitoring;
and 4, step 4: and according to the characteristic parameters of each composition structure of the dome structure to be detected under static and dynamic loads, performing health monitoring and safety evaluation on the dome structure through multi-characteristic fusion analysis.
2. The microwave radar-based dome structure health monitoring and safety assessment method according to claim 1, wherein said step 2 comprises:
step 2.1, selecting a multichannel intermediate frequency baseband signal of a certain sweep frequency period, obtaining a distance-angle image thermal image of the dome structure through two-dimensional fast Fourier transform, and positioning a full-field measuring point of the dome structure;
step 2.2, estimating phase evolution information of the key measuring point of the dome structure in each sweep frequency period, wherein the estimation method comprises the following steps:
Figure RE-FDA0002807103870000011
Figure RE-FDA0002807103870000012
indicates that the position information is (k)q,pq) Q1, 2.. Q. the phase information of the Q measuring point of the dome structure in the i transmitting period, kqAnd pqAre respectively the firstDistance dimension index and angle dimension index of distance-angle image heat map matrix corresponding to q measuring points, T is repeated emission period of linear frequency modulation signal, arg [ ·]For taking complex phase operations, si(. h) is the ith transmit period multi-channel IF baseband signal matrix, NfftDiscrete number of points, M, for fast Fourier transform in step 2.1 along each channel directionfftDiscrete points of fast Fourier change along the multi-channel direction in the step 2.1 are counted, M is the equivalent number of receiving channels, N is the discrete points of the intermediate frequency baseband signal of each channel in a single transmitting period, j is an imaginary number unit, e is an exponential form, and pi is a circumferential rate;
step 2.3, extracting deformation and vibration displacement time domain information:
Figure RE-FDA0002807103870000021
λcis the wavelength corresponding to the center frequency of the carrier wave of the linear frequency modulation continuous wave,
Figure RE-FDA0002807103870000022
is composed of
Figure RE-FDA0002807103870000023
Average value of (phi)qThe included angle between the deformation of the qth measuring point and the vibration direction and the radar sight line direction is shown.
And x (q, iT) is a deformation and vibration displacement extraction value of the qth measuring point in the ith emission period.
3. The microwave radar-based dome structure health monitoring and safety assessment method according to claim 2, wherein said step 2.1 comprises:
firstly, fast Fourier transform is carried out on the medium-frequency baseband signals of the single sweep frequency period and the multiple channels along each channel direction to obtain distance dimension information of the dome structure to be detected, then fast Fourier transform is carried out again along the multiple channels to obtain angle dimension information of the dome structure, and therefore joint full-field positioning of the dome structure in the distance dimension and the angle dimension is achieved.
4. The microwave radar-based dome structure health monitoring and safety assessment method according to claim 2, wherein said step 3 comprises:
step 3.1, cable force monitoring, namely performing frequency spectrum analysis on the cable vibration displacement time domain information measured in the step 2.3, and extracting the first-order natural frequency f of the measured cable vibrationpAnd calculating the cable force according to the mathematical relationship between the cable force of the stay cable and the first-order natural frequency of the stay cable as follows:
Figure FDA0002731199090000024
Fpp is the linear density of the cable, and L is the cable force of the P-th cable in the monitoring rangepThe length of the p-th inhaul cable is shown;
3.2, monitoring deformation, namely extracting the displacement deformation quantity of the steel rod type structure in the dome structure under the action of static load through the step 2.3;
and 3.3, vibration monitoring, namely monitoring vibration displacement time domain information of the dome steel rod structure under natural excitation, and identifying modal parameters of the structure through modal analysis.
5. The microwave radar-based dome structure health monitoring and safety assessment method according to claim 1, wherein said step 4 comprises:
performing multi-feature fusion analysis on the characteristic parameters of the dome structure extracted in the step 3 under the static and dynamic loads through experience analogy, theoretical analysis and specification requirements, and performing health monitoring and safety evaluation on the dome structure;
the criteria for the security assessment include: whether the cable force of the stay cable exceeds the bearing limit of the stay cable, whether the deformation of the steel rod type structure exceeds the design range under the action of load, and whether the natural frequency of the structure exceeds the threshold range and the change of the mode vibration type due to fatigue or damage.
6. A dome structure health monitoring and safety assessment system based on microwave radar is characterized by comprising:
a microwave radar module: transmitting and receiving a linear frequency modulation continuous wave microwave signal to a dome structure to be detected to generate a multi-channel intermediate frequency baseband signal;
the signal acquisition and processing module: calculating to obtain a distance-angle image thermal map of the dome structure to be measured according to the multi-channel intermediate frequency baseband signal, positioning the dome structure full-field measuring points from the distance-angle combined dimension, and synchronously extracting deformation and vibration displacement time domain information of each key measuring point;
a signal analysis module: according to deformation and vibration displacement time domain information of each measuring point, characteristic parameters of each composition structure of the dome structure to be measured under static and dynamic loads are extracted through cable force monitoring, deformation monitoring and vibration monitoring, and health monitoring and safety assessment are carried out on the dome structure through multi-characteristic fusion analysis.
7. The microwave radar-based dome structure health monitoring and safety assessment system of claim 6, wherein said microwave radar module comprises: the device comprises a linear frequency modulation continuous wave microwave signal source, a power divider, a power amplifier, a low noise amplifier, a mixer, a low pass filter, a transmitting antenna and a receiving antenna.
8. The microwave radar-based dome structure health monitoring and safety assessment system according to claim 7, wherein the number of said transmitting antennas is one or more, and the transmitting antennas transmit chirp continuous wave microwave signals to cover the dome structure to be tested;
the number of the receiving antennas is multiple, and the receiving antennas are distributed in a linear equal-spacing array.
9. The microwave radar-based dome structure health monitoring and safety assessment system of claim 6, further comprising:
the display and early warning module: and displaying the distance-angle image thermal image of the dome structure and deformation and vibration displacement time domain information of each measuring point obtained by the signal acquisition and processing module, sending early warning according to the results of health monitoring and safety evaluation by the signal analysis module and the results of health monitoring and safety evaluation, and storing the output results of the microwave radar module, the signal acquisition and processing module and the signal analysis module as required.
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