A building digital image deformation monitoring system based on radar correction

Abstract

The application discloses a kind of digital image deformation monitoring systems of building based on radar correction.The system includes visual measurement equipment, radar measurement equipment, column, data acquisition and algorithm equipment.New project often leads to deformation of adjacent existing building, and even destruction.Automatic monitoring is an effective way to ensure the safety of existing buildings.The measurement accuracy of traditional automatic total station and present digital image deformation monitoring is greatly affected by weather and other environmental factors, and even cannot be measured in rain and fog.Microwave radar ranging has the important advantages of high monitoring accuracy and small environmental factors.But radar ranging can only test the linear distance between the test point and the target point, and cannot obtain the two-dimensional or three-dimensional deformation of the target point.The application utilizes the advantages of high environmental resistance of microwave radar, calibrates the errors caused by digital image deformation monitoring technology in complex environmental conditions, and realizes the automatic monitoring of object displacement in multiple points, real-time, long distance, low cost and breaking the environmental condition restrictions.

Description

Technical Field

[0001] This invention relates to the field of deformation monitoring in civil engineering, and more particularly to the field of digital image deformation monitoring. Background Technology

[0002] With urbanization and increasingly dense urban construction, it is inevitable that new projects will impact nearby existing buildings and structures, such as the impact of foundation pit excavation on adjacent buildings. Current technical specifications require deformation monitoring of nearby existing buildings and structures to ensure safety. Traditional monitoring methods use total stations or levels to monitor the horizontal and vertical displacements of nearby existing buildings and structures. However, traditional monitoring methods are manual, infrequent, and cannot provide real-time monitoring or early warning. Automated monitoring methods are crucial for achieving real-time monitoring and early warning.

[0003] Currently, automated deformation monitoring of buildings mainly utilizes methods such as static levels and automatic total stations. Static levels can only measure settlement, not three-dimensional deformation. Furthermore, because static levels use hydraulic differential pressure for settlement measurement, they are unsuitable for monitoring projects with large elevation differences. Automatic total stations are costly, have limited measurement distances, and their accuracy is greatly affected by weather conditions, even failing in rainy or foggy weather. Digital image deformation monitoring technology is also being used for automated monitoring. This technology uses single, dual, or multiple cameras to acquire images of the target object, which are then processed by a computer using algorithms to obtain relevant data, thus achieving the monitoring purpose. Compared to traditional methods using instruments and sensors, digital image deformation monitoring offers advantages such as low cost and ease of automation. However, this technology is susceptible to environmental factors, leading to significant errors, and may even be unable to measure in rainy or foggy weather.

[0004] Radar is a technology that uses radio waves for detection and ranging. Microwave radar used for ranging has important advantages such as high monitoring accuracy and low susceptibility to environmental factors. However, radar ranging can only measure the linear distance between the test point and the target point, and cannot obtain the two-dimensional or three-dimensional deformation of the target point, which greatly limits the application of radar in engineering measurement of target deformation.

[0005] Patent CN112711033A discloses a slope safety monitoring and early warning device and method, while patent CN113762623A discloses a method, device, and electronic equipment for identifying and predicting landslide direction and trend. However, neither of these discloses a method for calibrating the error of digital image deformation detection technology under complex environmental conditions, thus failing to achieve high-precision multi-point real-time displacement measurement under complex environmental conditions. Patent CN109856633A discloses a modular foundation slope radar monitoring system; however, it uses radar as the calibrated object and does not disclose a method for jointly calibrating the measured object using radar and digital image correlation algorithms as a test system, thus failing to achieve high-precision automated monitoring of object displacement. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention utilizes the advantages of microwave radar's high resistance to environmental influences to calibrate the errors caused by digital image deformation monitoring technology under complex environmental conditions, thereby achieving automated monitoring of object displacement at multiple points, in real time, over long distances, at low cost, and breaking through environmental limitations.

[0007] To achieve the above objectives, the present invention provides a method for monitoring deformation of buildings based on radar-corrected digital images, comprising the following steps:

[0008] Step 1: At times T0 and T1, the binocular camera and microwave radar test the same target point and transmit the data to the data acquisition terminal via wireless communication equipment.

[0009] Step 2: The binocular camera data is processed and analyzed using a Digital Image Correlation (DIC) algorithm to establish a three-dimensional coordinate system (XYZ). The line connecting the target point to the radar and the binocular camera is perpendicular to the XZ coordinates at time T0. The DIC algorithm is then used to obtain digital images and the target point deformation (Δx) at times T0 and T1 calculated from these images. p Δy p Δz p );

[0010] Step 3: Calculate the target point movement distance ΔL p The calculation formula is:

[0011] Step 4: The algorithm program processes and analyzes the microwave radar data to obtain the distances between the microwave radar and the target point at times T0 and T1, which are L0 and L1, respectively.

[0012] Step 5: θ is the angle between the connecting line of the microwave radar and point A0 and the connecting line of the microwave radar and point A1; β is the angle between the connecting line of the microwave radar and point A1 and the connecting line of point A0 and point A1; ΔL is the moving distance of the target point after coupling; the coordinates of point A0 (x0, y0, z0) are the coordinates of the target point at time T0, and the coordinates of point A1 (x1, y1, z1) are the coordinates of the same target point at time T1; the parameters θ, β, and ΔL are solved respectively using the following formulas:

[0013]

[0014]

[0015]

[0016] Step 6: Calculate the error coefficient K, and the calculation formula is K=ΔL / ΔL p ; Solve the coordinate correction coefficient f according to the error coefficient K x , f y , f z ;

[0017] Step 7: According to the coordinate correction coefficient f x , f y , f z Solve the deformation of the target point obtained by correcting the digital image, that is, (f x Δx p , f y Δy p , f z Δz p );

[0018] Step 8: Repeat Step 3 to Step 7 until the error coefficient K is less than the error standard K p , and the finally obtained deformation of the target point is the corrected displacement of the target point.

[0019] Preferably, in Step 6, the calculation formula of the coordinate correction coefficient f i (i=x, y, z) is f i =F i (K); f i =F i (K)=aK+b, the values of a and b shall satisfy: 1<aK+b<K, 0.9<a<1, -0.03<b<0.03 or K<aK+b<1, 1.0<a<1.1, -0.03<b<0.03.

[0020] Preferably, the value range of Kp is 0.9 to 1.

[0021] Preferably, the binocular camera and the microwave radar can perform multi-target monitoring at the same time.

[0022] On the other hand, the present invention provides a digital image deformation monitoring system for buildings based on radar correction, including: visual measurement equipment, radar measurement equipment, columns, and data acquisition and algorithm equipment;

[0023] The visual measurement device includes a binocular camera and a camera connector; the binocular camera is used to capture images of the target point; different pixel binocular cameras are selected according to the range of the measurement distance to realize the deformation monitoring of the target point at different distances; the camera connector connects the camera to the column by bolts, which serves to install and fix the camera.

[0024] The radar measurement equipment includes a microwave radar and a radar connector; the microwave radar is used to measure the distance between the radar and the target point; different power microwave radars are selected according to the range of the measurement distance to realize the deformation monitoring of the target point at different distances; the radar connector connects the microwave radar to the column by bolts, which serves to install and fix the microwave radar.

[0025] The data acquisition and algorithm device includes a wireless communication device, a data acquisition terminal, and an algorithm program; the wireless communication device provides communication for the data from the binocular camera and microwave radar, and transmits it to the data acquisition terminal; the data acquisition terminal is used to store the data; the algorithm program analyzes the data from the binocular camera and microwave radar, and executes the monitoring methods described in steps 1-8 above to obtain the corrected target point displacement.

[0026] Preferably, the support column is made of steel pipe, which serves to support the microwave radar and the binocular camera. The support column is installed in a non-affected area of ​​the project to avoid deformation of the column caused by construction work, which would affect the measurement accuracy.

[0027] Preferably, the height of the steel pipe is adjusted according to the height of the monitored target to avoid obstruction between the microwave radar, the binocular camera and the target point.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) The present invention integrates microwave radar ranging technology and digital image deformation monitoring technology. Based on digital image correlation algorithms, it adds control over environmental variables to improve adaptability to various environments.

[0030] 2) The algorithm program of this invention has built-in error discrimination. Different error standards can be set according to different target deformation monitoring requirements to achieve measurement with different precision. The minimum precision reaches 0.1 mm level, realizing long-distance high-precision measurement.

[0031] 3) The lightweight displacement testing system based on vision sensing of this invention is simple to operate, has low equipment cost, high accuracy, obvious effect, and is easy to disseminate, promote and improve. Attached Figure Description

[0032] Figure 1 A schematic diagram for measuring building deformation.

[0033] Figure 2 This is a schematic diagram illustrating the measurement principle.

[0034] Figure 3 This is a schematic diagram of the algorithm calculation. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments.

[0036] This invention provides a radar-corrected digital image deformation monitoring system for buildings, comprising a visual measurement device, a radar measurement device, a column, and a data acquisition and algorithm device. The visual measurement device mainly includes a binocular camera and a camera connector. The radar measurement device mainly includes a microwave radar and a radar connector. The data acquisition and algorithm device includes a wireless communication device, a data acquisition terminal, and an algorithm program.

[0037] like Figure 1 As shown, the camera connector uses bolts to attach the camera to the column, and the radar connector uses bolts to attach the microwave radar to the column. The column, made of steel pipe, supports the microwave radar and the binocular camera. The height of the steel pipe is adjustable according to the height of the monitored target; a reasonable selection of the steel pipe height avoids obstruction between the microwave radar, binocular camera, and the target point. The column is installed in a non-affected area of ​​the project to prevent deformation caused by construction work, which could affect measurement accuracy.

[0038] A binocular camera is used to capture images of the target point. Different pixel binocular cameras are selected based on the measurement distance; in this embodiment, a 6-megapixel binocular camera is selected. A microwave radar is used to measure the distance between the radar and the target point. Different power microwave radars are selected based on the measurement distance; in this embodiment, a 200-meter ranging radar is selected to achieve target point deformation monitoring at this distance. A wireless communication device provides communication between the binocular camera and the microwave radar, transmitting the data to a data acquisition terminal. The data acquisition terminal stores all data, including measurement data and deformation data calculated by the algorithm. The algorithm program analyzes the binocular camera and microwave radar data to calculate and correct the target point displacement. This includes the following steps:

[0039] Step 1: At times T0 and T1, the binocular camera and microwave radar test the same target point and transmit the data to the data acquisition terminal via wireless communication equipment. In this embodiment, T0 is 00:29:41 and T1 is 00:49:41. The binocular camera and microwave radar can acquire data from multiple targets simultaneously.

[0040] Step 2: The DIC (Digital Image Correlation) algorithm process and analyzes the binocular camera data, establishing a three-dimensional coordinate system (XYZ). The line connecting the target point to the radar and the binocular camera is made perpendicular to the XZ coordinates at time T0. Figure 2 As shown, the coordinates of point A0 (x0, y0, z0) are the coordinates of the target point at time T0, and the coordinates of point A1 (x1, y1, z1) are the coordinates of the same target point at time T1. The distances between the microwave radar and the target point at times T0 and T1 are L0 and L1, respectively. A digital image correlation algorithm is used to obtain the digital image and the target point deformation (Δx) at times T0 and T1 calculated from the digital image. p Δy p Δz p In this embodiment, the target point is deformed to (3.300143, 3.410465, 0.104847) mm.

[0041] Step 3: Calculate the target point movement distance ΔL p The calculation formula is: The calculation result is ΔL p = 4.746916 mm.

[0042] Step 4: The algorithm program processes and analyzes the microwave radar data to obtain the distances between the microwave radar and the target point at times T0 and T1, which are L0 and L1, respectively. In this embodiment, L0 is calculated to be 2785.678 mm and L1 is calculated to be 2788.745 mm.

[0043] Step 5: Solve for parameters θ, β, and ΔL using the following formulas, with the relative relationships as follows: Figure 3 As shown, θ is the angle between the lines connecting the microwave radar and point A0, and between the microwave radar and point A1; β is the angle between the lines connecting the microwave radar and point A1, and between points A0 and A1. ΔL is the distance the target point moves after coupling. In this embodiment, the solution is θ = 0.067812°, β = 49.727207°, and ΔL = 4.321585 mm.

[0044]

[0045]

[0046]

[0047] Step 6: Calculate the error coefficient K, where the calculation formula is K=ΔL / ΔL p , and the calculation result in this embodiment is K=0.911743. Solve the coordinate correction coefficients f according to the error coefficient K x , f y , f z . The coordinate correction coefficients f i (i=x, y, z) have the calculation formula f i =F i (K). The function F i (K) is obtained through laboratory calibration. The formula f i =F i (K) adopts a linear correlation form, and this linear correlation formula is applicable to the case where 0.9<K<1.1. Introduce coefficients a and b such that f i =F i (K)=aK+b, and the values of a and b shall satisfy: 1<aK+b<K, 0.9<a<1, -0.03<b<0.03; or K<aK+b<1, 1.0<a<1.1, -0.03<b<0.03. The value ranges of a and b are given based on the K value and the radar test accuracy, which can ensure that the variation range of each coordinate correction is within a reasonable range, and the corrected displacement can gradually approximate the real displacement. In this embodiment, f x =1.04K+0.02, f y =1.05K+0.01, f z =0.90K-0.02.

[0048] Step 7: According to the coordinate correction coefficients f x , f y , f z solve the deformation of the target point calculated from the corrected digital image, that is, (f x Δx p , f y Δy p , f z Δz p ). In this embodiment, the coordinate correction coefficients f x , f y , f z are 0.968212, 0.967330, and 0.801330 respectively.

[0049] Step 8: Since the calculation formula for the error coefficient uses the coordinates of the initial target point, there is a possibility that a single error assessment may not be sufficient to completely correct the error and obtain the ideal accuracy. Therefore, iterative calculation may be necessary. Repeat steps 3 to 7 until the error coefficient K value is greater than the error standard K. p The ideal value of Kp is 1. However, due to inherent errors in the actual process, Kp can be 0.95 or 0.9. The closer Kp is to 1, the more accurate the deformation result of the target point. In this embodiment, K... p Taking a value of 0.9, the final result is the corrected deformation of the target point, which is (2.99234, 3.086665, 0.067314) mm.

[0050] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A method for monitoring deformation of buildings and structures based on radar correction digital images, characterized in that, Includes the following steps: Step 1: At times T0 and T1, the binocular camera and microwave radar test the same target point and transmit the data to the data acquisition terminal via wireless communication equipment. Step 2: Process and analyze the binocular camera data using the Digital Image Correlation (DIC) algorithm to establish a three-dimensional coordinate system (XYZ), ensuring that the line connecting the target point to the radar and the binocular camera is perpendicular to the XZ coordinates at time T0; use the DIC algorithm to obtain digital images and the target point deformations at times T0 and T1 calculated from the digital images. ; Step 3: Calculate the distance the target point has moved. The calculation formula is: ; Step 4: The algorithm process and analyzes the microwave radar data to obtain the distances between the microwave radar and the target point at times T0 and T1, respectively. , ; Step 5: θ is the angle between the lines connecting the microwave radar and point A0, and between the microwave radar and point A1; β is the angle between the lines connecting the microwave radar and point A1, and between point A0 and point A1; ∆L is the distance the target point moves after coupling; the coordinates of point A0 are... ) represents the coordinates of the target point at time T0, and the coordinates of point A1 are ( Let T1 be the coordinates of the same target point; the parameters are solved using the following formulas. , , : Step 6: Calculate the error coefficient , and the calculation formula is ; according to the error coefficient , solve the coordinate correction coefficient , , ; the calculation formula for the coordinate correction coefficient ( ) in the step 6 is ; =aK+b, the values of a and b shall satisfy: 1<aK+b<K, 0.9<a<1, -0.03<b<0.03 or K<aK+b<1, 1.0<a<1.1, -0.03<b<0.03; Step 7: Based on coordinate correction coefficients , , Solve for the deformation of the target point obtained from the calculation of the corrected digital image, i.e. ; Step 8: Repeat steps 3 to 7 until the error coefficient is reached. Less than the error standard The final target point deformation is the corrected target point displacement.

2. The monitoring method according to claim 1, wherein... The value range is from 0.9 to 1.

3. According to the monitoring method described in claim 1, the binocular camera and microwave radar can simultaneously monitor multiple targets.

4. A digital image deformation monitoring system for buildings based on radar correction, characterized in that, include: Visual measurement equipment, radar measurement equipment, support columns, data acquisition and algorithm equipment; The visual measurement device includes a binocular camera and a camera connector; The binocular camera is used to capture images of the target point; different pixel binocular cameras are selected according to the range of the measurement distance to realize the deformation monitoring of the target point at different distances; The camera connector connects the camera to the column using bolts. The radar measuring equipment includes a microwave radar and a radar connector; the microwave radar is used to measure the distance between the radar and the target point; different power microwave radars are selected according to the range of the measurement distance to realize the deformation monitoring of the target point at different distances; the radar connector connects the microwave radar to the column by bolts; The data acquisition and algorithm device includes a wireless communication device, a data acquisition terminal, and an algorithm program; the wireless communication device provides communication for the data from the binocular camera and microwave radar, and transmits it to the data acquisition terminal; the data acquisition terminal is used to store the data; the algorithm program analyzes the data from the binocular camera and microwave radar, and executes the monitoring method according to any one of claims 1-3 to obtain the corrected target point displacement.

5. In the monitoring system according to claim 4, the column is a steel pipe, which serves to support the microwave radar and the binocular camera. The column is installed in the non-affected area of ​​the project to avoid deformation of the column caused by the construction.

6. The monitoring system according to claim 5, wherein the height of the steel pipe is adjusted according to the height of the monitoring target to avoid obstruction between the microwave radar, the binocular camera and the target point.

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