CN112147627A - Building structure and surface abnormal change detection method based on micro-motion attribute laser detection - Google Patents

Building structure and surface abnormal change detection method based on micro-motion attribute laser detection Download PDF

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CN112147627A
CN112147627A CN202011109785.8A CN202011109785A CN112147627A CN 112147627 A CN112147627 A CN 112147627A CN 202011109785 A CN202011109785 A CN 202011109785A CN 112147627 A CN112147627 A CN 112147627A
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vibration
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胡晨阳
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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
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/50—Systems of measurement based on relative movement of target
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
    • 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
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4818—Constructional features, e.g. arrangements of optical elements using optical fibres
    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/4861—Circuits for detection, sampling, integration or read-out

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

The invention belongs to the technical field of detection, and particularly relates to a building structure and surface abnormal change detection method based on micromotion attribute laser detection, which comprises the following steps: deploying an all-fiber coherent laser scanning detection system at a proper position of a measured object; selecting working parameters of a detection system according to actual task requirements and surrounding environment characteristics; setting parameters such as a detection range, a scanning path, scanning stepping, each point scanning residence time and the like in a scanning system according to a building to be detected; scanning and detecting a target, receiving an echo signal, analyzing and processing the echo signal, and calculating the vibration amplitude and the vibration frequency of each scanning point; the building structure and surface abnormal change detection method based on micromotion attribute laser detection belongs to nondestructive non-contact detection and can obtain vibration distribution images with different resolutions as required.

Description

Building structure and surface abnormal change detection method based on micro-motion attribute laser detection
Technical Field
The invention belongs to the technical field of detection, and particularly relates to a building structure and surface abnormal change detection method based on micromotion attribute laser detection.
Background
With the increase of the service time, the life and property safety of people are threatened all the time by the falling of the building appearance and the safety accidents caused by the change of the internal structure. Therefore, the nondestructive testing system has a wide application foundation for safety detection and service life prediction of engineering quality such as structural and surface abnormality of buildings (houses, bridges, tunnels and the like), and is widely used in the field at present. The main non-destructive testing means for engineering quality testing of building structure and surface anomalies are:
1. the thermal infrared imager method is convenient and quick to detect by utilizing the temperature difference of a normal area and a crack hollowing area under sunlight, and can be used for detecting the fields of building wall stripping, hollowing, house heat preservation airtightness, fire concrete damage and the like. However, the material which is not obviously changed in temperature, such as a rigid hanging type or a glass curtain wall, is useless when the sun shines on a sunny day.
2. The ultrasonic detection method is nondestructive, can detect the internal structure of an object, is convenient and safe, but requires two opposite test surfaces due to penetration test, and has the defects of a plurality of test points, and the ultrasonic detection method is not suitable for single-surface structures such as roads, bottom plates and the like.
3. The impact reflection detection is that micro shock waves are applied to the surface of a structure to generate stress waves, and when the stress waves encounter defects and the bottom surface of the structure causes micro displacement response, so that the method is a nondestructive detection method capable of detecting the defects of the internal structure of the concrete, and can carry out intuitive and accurate single-side test. This is similar to the micro-motion detection idea, but the processing method is different, and belongs to contact detection.
4. The radar detection has strong penetrability, can measure an internal structure, and is widely applied to ground detection engineering at present. However, the electromagnetic wave measurement has a serious problem in identifying the multi-layer steel bars, so that the application of the electromagnetic wave in the position detection of the concrete steel bars has certain limitation.
5. A spectral analysis detection technique. The different frequencies of the surface wave propagating in different constructional engineering media are utilized. A vertical force is applied to a road surface to form a vibration source, sensors are arranged at different positions to detect the frequency of wave propagation, and the purpose of testing the mechanical parameters of the medium can be achieved by means of cross-spectrum analysis and coherence analysis technology of a frequency domain. But also requires a contact-less probing and is complicated.
It can be seen that the existing method has low resolution, most of the methods need contact measurement, and the requirements on time and environment are high.
Disclosure of Invention
The invention aims to provide a building structure and surface abnormal change detection method based on micro-motion attribute laser detection, which utilizes the fact that an object has micro-motion characteristics in a natural environment to detect the change information of micro-motion characteristic parameters of the object so as to judge the abnormal change condition of the structure and the surface of the object, belongs to nondestructive non-contact detection, has better detection precision than the existing method, and can obtain vibration distribution images with different resolutions as required.
In order to achieve the above purpose, the invention adopts the technical scheme that: a building structure and surface abnormal change detection method based on micromotion attribute laser detection comprises the following steps:
(1) deploying an all-fiber coherent laser scanning detection system at a proper position of a measured object;
(2) selecting working parameters of a detection system according to actual task requirements and surrounding environment characteristics;
(3) setting parameters such as a detection range, a scanning path, scanning stepping, each point scanning residence time and the like in a scanning system according to a building to be detected;
(4) scanning and detecting a target, receiving an echo signal, analyzing and processing the echo signal, and calculating the vibration amplitude and the vibration frequency of each scanning point;
(5) and generating an amplitude and vibration frequency image corresponding to the target according to the calculated vibration parameters of each scanning point, and judging whether the surface of the structure is abnormal or not.
Further, the all-fiber coherent laser scanning detection system in the step (1) is an all-fiber coherent laser heterodyne detection structure, the laser wavelength is 1550nm, and the laser passes through the collimator and then is injected into the scanning system to irradiate the target.
Further, the scanning system in step (3) is a two-dimensional scanning system in which the parameters of scanning range, route, step and interval can be controlled and recorded by software.
Further, the signal analysis processing and vibration amplitude and vibration frequency calculation method in the step (4) is mainly realized by a parameterized micro doppler signal parameter estimation method.
The invention has the technical effects that: the non-contact nondestructive detection of the exterior surface and the structure of the building is realized, the influence of environment, weather, day and night and the like is small, and the operation risk and the cost are reduced; by using a parametric signal processing method, the required data volume is small, the scanning and signal processing time is reduced, and a detection image is rapidly acquired; the detection precision by using coherent laser is high, and different vibration image resolutions can be obtained by adjusting scanning parameters.
Drawings
FIG. 1 is a schematic diagram of a coherent laser scanning probe configuration;
FIG. 2 is a comparison of the excitation signal and the detection signal at the ith row and jth row of scanning points;
fig. 3 is a comparison of the excitation signal IF and the IF of the TVAR estimate.
Detailed Description
The building structure and surface abnormal change detection method based on micromotion attribute laser detection comprises the following steps:
(1) deploying an all-fiber coherent laser scanning detection system at a proper position of a measured object;
(2) selecting working parameters of a detection system according to actual task requirements and surrounding environment characteristics;
(3) setting parameters such as a detection range, a scanning path, scanning stepping, each point scanning residence time and the like in a scanning system according to a building to be detected;
(4) scanning and detecting a target, receiving an echo signal, analyzing and processing the echo signal, and calculating the vibration amplitude and the vibration frequency of each scanning point;
(5) and generating an amplitude and vibration frequency image corresponding to the target according to the calculated vibration parameters of each scanning point, and judging whether the surface of the structure is abnormal or not.
Preferably, the all-fiber coherent laser scanning detection system in the step (1) is an all-fiber coherent laser heterodyne detection structure, the laser wavelength is 1550nm, and the laser passes through a collimator and then is injected into the scanning system to irradiate the target.
Preferably, the scanning system in step (3) is a two-dimensional scanning system in which the parameters of scanning range, route, step and interval can be controlled and recorded by software.
Preferably, the signal analysis processing, vibration amplitude and vibration frequency calculation method in the step (4) is mainly implemented by a parameterized micro doppler signal parameter estimation method.
The received echo light signal can be written as
Figure BDA0002728224300000041
Wherein γ represents the complex scattering intensity of the P point, λcIndicating the wavelength of the laser, fc＝c/λcIs the laser frequency, c is the speed of light, B ═ 4 π/λc)Dvcos β cos α, α and β represent the azimuth and elevation angles of the scan, provided by the scanning system, ρ0For the initial phase of the micromotion, v is the relative velocity of the detection system and the target, here 0, R0Represents the initial distance, ω (t) represents the signal noise;
the echo optical signal and the local oscillator light output an intermediate-frequency photocurrent signal i after passing through the photoelectric detector, which can be characterized as
Figure BDA0002728224300000051
A represents the current intensity, the coherent signal does not contain the initial distance term, and the target is excited to generate the vibration frequency f of weak vibrationvAnd amplitude of vibration DvContained in the signal phase.
The phase in the above formula is derived to obtain the micro Doppler frequency shift of the signal caused by the target vibration
Figure BDA0002728224300000052
The micro Doppler frequency shift of the signal also reflects the change of the Instantaneous Frequency (IF) of the signal, so that the vibration parameter of the target is solved only by analyzing and processing the instantaneous frequency of the signal, and the requirement on whether the strength of the echo signal is uniform or not is not high;
the instantaneous frequency of the signal is extracted using a time-varying autoregressive (TVAR) model.
The TVAR model belongs to a parameterization method, when a signal IF is extracted, the resolution is not influenced by the signal length, namely accurate IF information can be obtained under the condition of less data volume, so that the scanning dwell time and the signal processing time of each point can be reduced, and the target detection efficiency is improved under the condition of ensuring the resolving accuracy of vibration parameters.
The TVAR model of a general p-th order zero-mean discrete time series can be written as
Figure BDA0002728224300000053
n represents the number of discrete points, ai(n) represents the ith order model coefficient, only the first order TVAR model is needed for the single component micro Doppler signal, and the electric signal in the step 4b can be represented as
Figure BDA0002728224300000054
And performing z transformation on the above formula to obtain a TVAR model characteristic equation, and solving the root of the equation to obtain an instantaneous pole p (n) of the corresponding signal. For the first-order model, the poles and the time-varying coefficients are opposite numbers, and the specific relationship can be expressed as:
a(n)＝-p(n) (6)
the instantaneous frequency can be obtained by the poles of the model
Figure BDA0002728224300000061
fsIs the signal sampling frequency. The scanning interval of the scanning device is twice the vibration period of the vibration source, i.e. the dwell time at each point is ts＝2/fsEnough signal length can be provided for parameter calculation;
and (5) estimating the vibration amplitude and frequency of the vibration source by using a parameterization method. Because the echo signal is a single-component micro-Doppler signal, the instantaneous frequency curve extracted in the step 4c is in a sine curve form, the curve can be fitted by directly adopting the lowest two multiplications, and the amplitude of the echo signal IF curve at the current scanning point can be quickly estimated
Figure BDA0002728224300000062
Sum frequency
Figure BDA0002728224300000063
Then
Figure BDA0002728224300000064
Preferably, the specific method for generating the amplitude and vibration frequency image corresponding to the target according to the calculated vibration parameter of each scanning point in the step (5) and judging whether the surface has the abnormal structure includes: arranging the vibration frequency and vibration amplitude of each scanning point calculated in the step 4 into a data matrix according to the scanning path, and generating a two-dimensional or three-dimensional amplitude distribution image and a vibration frequency distribution image in the target scanning range according to the sum. In combination with the actual structure of the object, the images are compared and abnormal vibrations of the surface can be found. For the monitoring of the same target quality change condition, the second detection can be carried out under the same parameter setting condition, a new data matrix sum is generated, and the target change condition in the detection period can be obtained by subtracting twice.
The specific implementation mode is as follows:
1. setting full-optical-fiber coherent laser scanning detection system, laser wavelength 1.55 μm, sampling rate 5 × 104Hz；
2. The method is applied to building curtain wall micro-motion measurement, is carried out in a relatively constant breeze environment, the illumination condition is not limited, and the influence of the peripheral vehicle passing condition on the building micro-motion needs to search for a rule in advance;
3. setting a scanning detection range in the scanning system according to the building to be detected, wherein the scanning range of the direction angle is as follows: alpha is alpha1→α2Pitch angle scan range beta1→β2The dwell time of each point of scanning is 2/150s of two vibration periods, and the transverse and longitudinal scanning steps are respectively as follows: (alpha2-α1) Image lateral resolution (beta)2-β1) Image lateral resolution;
4. scanning and detecting a target, receiving echo signals and analyzing, wherein the azimuth angle alpha is taken as an example of the ith row and the jth line scanning position echo signalsiAngle of pitch betajThe echo signals are shown in FIG. 2; extracting a signal IF curve by using a TVAR model, as shown in fig. 3; estimating the amplitude of an IF curve using a least squares method
Figure BDA0002728224300000071
Sum frequency
Figure BDA0002728224300000072
The actual vibration frequency of the point is calculated according to a formula
Figure BDA0002728224300000073
Amplitude of
Figure BDA0002728224300000074
And resolving the vibration parameters of each scanning point according to the steps.
5. Arranging the data matrix f according to the calculated vibration parameters of each scanning point and the scanning pathvAnd DvAccording to fvAnd DvTwo-dimensional or three-dimensional amplitude distribution images and vibration frequency distribution images within the target scanning range can be generated.

Claims (4)

1. The building structure and surface abnormal change detection method based on micromotion attribute laser detection is characterized by comprising the following steps of:
(1) deploying an all-fiber coherent laser scanning detection system at a proper position of a measured object;
(2) selecting working parameters of a detection system according to actual task requirements and surrounding environment characteristics;
(3) setting parameters such as a detection range, a scanning path, scanning stepping, each point scanning residence time and the like in a scanning system according to a building to be detected;
(4) scanning and detecting a target, receiving an echo signal, analyzing and processing the echo signal, and calculating the vibration amplitude and the vibration frequency of each scanning point;
(5) and generating an amplitude and vibration frequency image corresponding to the target according to the calculated vibration parameters of each scanning point, and judging whether the surface of the structure is abnormal or not.
2. The method for detecting abnormal changes in a building structure and surface based on micro-motion attribute laser detection as claimed in claim 1, wherein: the all-fiber coherent laser scanning detection system in the step (1) is an all-fiber coherent laser heterodyne detection structure, the laser wavelength is 1550nm, and the laser is injected into the scanning system to irradiate a target after passing through a collimator.
3. The method for detecting abnormal changes in a building structure and surface based on micro-motion attribute laser detection as claimed in claim 1, wherein: the scanning system in the step (3) is a two-dimensional scanning system, and parameters of scanning range, route, stepping and interval can be controlled and recorded by software.
4. The method for detecting abnormal changes in a building structure and surface based on micro-motion attribute laser detection as claimed in claim 1, wherein: the signal analysis processing, vibration amplitude and vibration frequency calculation method in the step (4) is mainly realized by adopting a parameterized micro Doppler signal parameter estimation method.
CN202011109785.8A 2020-10-16 2020-10-16 Building structure and surface abnormal change detection method based on micro-motion attribute laser detection Pending CN112147627A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113654647A (en) * 2021-06-29 2021-11-16 国网江苏省电力有限公司电力科学研究院 Non-contact GIL vibration detection method and device
CN114719754A (en) * 2022-03-07 2022-07-08 大连理工大学 High-speed rail simply supported beam expansion joint micron displacement low coherence optical monitoring system and method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113654647A (en) * 2021-06-29 2021-11-16 国网江苏省电力有限公司电力科学研究院 Non-contact GIL vibration detection method and device
CN114719754A (en) * 2022-03-07 2022-07-08 大连理工大学 High-speed rail simply supported beam expansion joint micron displacement low coherence optical monitoring system and method

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