Curve bridge single column pier deviation analysis and bridge floor damage evaluation method and system

Abstract

The invention discloses a curve bridge single-column pier deviation analysis and bridge floor damage evaluation method and system, and the method comprises the steps: selecting a curve bridge section single-column pier, and determining the pier point cloud data of the curve bridge section single-column pier; point cloud slices are determined for the pier point cloud data according to point cloud density, curve bridge single-column pier deviation analysis is carried out based on the point cloud slices, and pier perpendicularity is obtained; establishing a bridge deck point cloud topological relation, performing curved surface fitting of bridge deck local point cloud based on the bridge deck point cloud topological relation, and estimating a Gaussian curvature; and based on the pier perpendicularity and the Gaussian curvature, carrying out damage assessment on the bridge surface of the pier to obtain a damage assessment result. According to the invention, rapid and real-time structural health monitoring can be realized, the detection efficiency is improved, and manual errors are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering, and particularly relates to a method and system for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck. Background Art

[0002] At present, the mainstream method for bridge damage detection is to continuously and regularly observe the bridge through non-contact sensors, such as global positioning system, total station, spaceborne interferometric synthetic aperture radar, ground-based synthetic aperture radar and other technologies, so as to evaluate the construction safety and performance of the bridge. Although these detection methods have high accuracy in the inspection of points and angles, due to the limitations of small measurement range, time-consuming and laborious characteristics, it is difficult to accurately locate the key damage positions of the bridge. And because of the particularity of the bridge structure, the vast majority of damages and potential damages occur on the side or bottom of the bridge deck, and professional inspectors need to rely on certain mechanical equipment to accurately detect these positions. The ground three-dimensional laser scanning technology has the advantages of collecting a large number of data points, large data volume, non-contact, etc. It can calculate the spatial distance between the measured object and the scanner. In bridge damage detection, the measurement results usually include the geometric information and feature information of the collected points. By saving the three-dimensional spatial structure of the point cloud, a comprehensive, visual and accurate measurement result can be achieved. However, the three-dimensional laser scanning measurement has randomness and non-repeatability of multiple scans, and the periodically collected data will directly affect the timeliness of bridge health assessment and reduce the damage assessment efficiency.

[0003] Therefore, the existing technology still needs to be improved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and system for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck in view of the above-mentioned defects of the existing technology. The technical solutions adopted by the present invention are as follows:

[0005] In the first aspect, the present invention provides a method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck, wherein the method includes:

[0006] Select a single-column pier of a curved bridge section and determine the pier point cloud data of the curved bridge section;

[0007] Determine point cloud slices according to the point cloud density of the pier point cloud data, and perform deviation analysis of the single-column pier of the curved bridge based on the point cloud slices to obtain the pier verticality;

[0008] Establish a topological relationship of the bridge deck point cloud, perform surface fitting on the local point cloud of the bridge deck based on the topological relationship of the bridge deck point cloud, and estimate the Gaussian curvature;

[0009] Perform damage assessment on the pier and bridge deck based on the pier verticality and the Gaussian curvature to obtain a damage assessment result.

[0010] In one implementation, selecting the single-column pier of the curved bridge section and determining the pier point cloud data of the single-column pier of the curved bridge section includes:

[0011] Select the single-column pier of the curved bridge section, denoise the model of the single-column pier of the curved bridge section, eliminate the gross measurement errors, and optimize the point cloud data to obtain the pier point cloud data.

[0012] In one implementation, determining the point cloud slices of the pier point cloud data according to the point cloud density and performing the offset analysis of the single-column pier of the curved bridge based on the point cloud slices to obtain the pier verticality includes:

[0013] Based on the plane cutting function in the Officesurvey module of the Realworks software, obtain the point cloud slices of the pier, and use the Modeling module of the Realworks software to build a cylinder model for each point cloud slice to obtain the coordinates of several slice centers;

[0014] Based on the coordinates of the section center, eliminate the outliers and fit the circular curve parameters, and calculate the pier offset and the pier verticality.

[0015] In one implementation, based on the coordinates of the section center, eliminating the outliers and fitting the circular curve parameters includes:

[0016] Randomly select 3 points and determine whether the 3 selected points are on the same straight line;

[0017] Based on the 3 selected points, construct a circular curve, determine the distance from each point in the point cloud slice to the circular curve, and obtain the number of all points less than a preset threshold;

[0018] Traverse all the measurement points, find the group with the largest number of points, and perform least squares fitting based on all the points in the group with the largest number of points.

[0019] In one implementation, performing surface fitting on the local point cloud of the bridge deck based on the topological relationship of the bridge deck point cloud and estimating the Gaussian curvature includes:

[0020] Obtain the point cloud set of the lower surface of the bridge, perform plane fitting on the point cloud data of the lower surface of the bridge, and perform normal estimation of the point cloud to obtain the normal vector, and the normal vector is used to describe the direction of the local surface of the bridge deck;

[0021] Take the normal vector obtained by performing plane fitting on the point cloud data of the lower surface of the bridge as the vertical axis of the coordinate, and perform rotation and translation respectively based on this as the benchmark to establish a temporary coordinate system;

[0022] Taking the temporary coordinate system as the reference coordinate system, perform Gaussian curvature estimation on the reference coordinate system.

[0023] In one implementation, the method further includes:

[0024] Fitting the verticality of the pier and the offset of the pier to the height respectively to determine the relationship between the verticality of the single-column pier of the curved bridge and the height, and the relationship between the inclination of the single-column pier of the curved bridge and the height.

[0025] In one implementation, the damage assessment of the pier deck based on the verticality of the pier and the Gaussian curvature to obtain a damage assessment result includes:

[0026] If a sudden change occurs in the Gaussian curvature, it is determined that the degree of curvature change is large, and the potential damage area is determined.

[0027] In a second aspect, an embodiment of the present invention further provides a system for analyzing the deviation of a single-column pier of a curved bridge and assessing the damage of the bridge deck. Wherein, the system includes:

[0028] A point cloud data determination module, configured to select a single-column pier of a curved bridge section and determine the pier point cloud data of the single-column pier of the curved bridge section;

[0029] A pier inclination analysis module, configured to determine a point cloud slice according to the point cloud density for the pier point cloud data, and perform deviation analysis of the single-column pier of the curved bridge based on the point cloud slice to obtain the verticality of the pier;

[0030] A bridge deck curvature detection module, configured to establish a topological relationship of the bridge deck point cloud, perform surface fitting of the local point cloud of the bridge deck based on the topological relationship of the bridge deck point cloud, and estimate the Gaussian curvature;

[0031] A bridge deck damage assessment module, configured to perform damage assessment on the pier bridge deck based on the verticality of the pier and the Gaussian curvature to obtain a damage assessment result.

[0032] In a third aspect, an embodiment of the present invention further provides a terminal. Wherein, the terminal includes a memory, a processor, and a program for analyzing the deviation of a single-column pier of a curved bridge and assessing the damage of the bridge deck stored in the memory and executable on the processor. When the processor executes the program for analyzing the deviation of a single-column pier of a curved bridge and assessing the damage of the bridge deck, the steps of the method for analyzing the deviation of a single-column pier of a curved bridge and assessing the damage of the bridge deck in any one of the above solutions are implemented.

[0033] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium. Wherein, a program for analyzing the deviation of a single-column pier of a curved bridge and assessing the damage of the bridge deck is stored on the computer-readable storage medium. When the program for analyzing the deviation of a single-column pier of a curved bridge and assessing the damage of the bridge deck is executed by a processor, the steps of the method for analyzing the deviation of a single-column pier of a curved bridge and assessing the damage of the bridge deck in any one of the above solutions are implemented.

[0034] Beneficial effects: Compared with the prior art, the present invention provides a method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck. First, the single-column piers of the curved bridge section are selected, and the point cloud data of the piers of the curved bridge section are determined. Then, according to the point cloud density, point cloud slices are determined for the pier point cloud data, and based on the point cloud slices, the deviation of the single-column pier of the curved bridge is analyzed to obtain the pier verticality. Next, the topological relationship of the bridge deck point cloud is established, the surface fitting of the local point cloud of the bridge deck is carried out based on the topological relationship of the bridge deck point cloud, and the Gaussian curvature is estimated. Finally, based on the pier verticality and the Gaussian curvature, the damage of the pier and the bridge deck is evaluated to obtain the damage evaluation result. Through multiple iterations and threshold limitations, the present invention successfully removes the outliers in the data, improving the accuracy and reliability of circular fitting. In addition, the calculation of Gaussian curvature is based on point cloud data, enabling high-precision three-dimensional surface reconstruction and improving the accuracy and reliability of flaw detection. This method has a high degree of automation. Combining advanced algorithms and machine learning technologies, it can achieve fast and real-time structural health monitoring, improve the detection efficiency, and reduce human errors. With the continuous expansion of the application of point cloud data, the method of this embodiment is expected to play an important role in more fields, such as industrial inspection, robot navigation, three-dimensional modeling, etc., providing strong support for the development of related technologies. Description of the Drawings

[0035] Figure 1 It is a flowchart of a preferred embodiment of the method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by an embodiment of the present invention.

[0036] Figure 2 It is a schematic diagram of the technical route of the method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by an embodiment of the present invention.

[0037] Figure 3 It is a schematic diagram of the slice of the single-column pier in the method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by an embodiment of the present invention.

[0038] Figure 4 It is a display diagram of the sliced point cloud in the overall point cloud in the method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by an embodiment of the present invention.

[0039] Figure 5 It is a TXT file of the 200 point cloud coordinates of a single slice in the method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by an embodiment of the present invention.

[0040] Figure 6 It is a schematic flowchart of the removal of outliers and the fitting of circular curve parameters in the method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by an embodiment of the present invention.

[0041] Figure 7It is a visualization schematic diagram of the algorithms for each section of the single-column pier in the method for analyzing the deviation of the single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by the embodiments of the present invention.

[0042] Figure 8 It is the relationship between the inclination amount and the height of the single-column pier in the method for analyzing the deviation of the single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by the embodiments of the present invention.

[0043] Figure 9 It is the relationship between the verticality and the height of the single-column pier in the method for analyzing the deviation of the single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by the embodiments of the present invention.

[0044] Figure 10 It is the point cloud map of the middle bridge deck of the curved bridge section in the method for analyzing the deviation of the single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by the embodiments of the present invention.

[0045] Figure 11 It is a schematic diagram of obtaining the normal vector by performing normal estimation on the point cloud in the method for analyzing the deviation of the single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by the embodiments of the present invention.

[0046] Figure 12 It is a schematic diagram of the architecture of the system for analyzing the deviation of the single-column pier of a curved bridge and evaluating the damage of the bridge deck provided by the embodiments of the present invention.

[0047] Figure 13 It is a principle block diagram of the terminal provided by the embodiments of the present invention. Detailed implementation manners

[0048] To make the objectives, technical solutions and effects of the present invention clearer and more definite, the following further describes the present invention in detail with reference to the accompanying drawings and by way of examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] The flowcharts shown in the accompanying drawings are only illustrative examples, and do not necessarily include all the contents and operations or steps, nor do they necessarily need to be executed in the described order. For example, some operations or steps can also be decomposed, combined or partially merged, so the actual execution order may be changed according to the actual situation.

[0050] It should be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0051] It should be understood that, for the convenience of clearly describing the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, terms such as "first" and "second" are used to distinguish the same items or similar items with basically the same functions and roles. For example, the first control information and the second control information are only used to distinguish different control information, and do not limit their sequence.

[0052] Those skilled in the art can understand that terms such as "first" and "second" do not limit the quantity and execution order, and the terms "first" and "second" do not necessarily limit being different.

[0053] It should also be understood that the term "and / or" used in the specification and appended claims of the present invention refers to any combination and all possible combinations of one or more of the related listed items, and includes these combinations.

[0054] In current point cloud processing technologies, using the least squares method for circular fitting has become a common approach. However, with the widespread use of point cloud data in various application fields, the traditional least squares method has revealed many deficiencies when dealing with actual data, especially in the face of the inevitable uncertainties and high interference during the data collection process. These uncertainties and interferences are mainly reflected in the presence of a large number of noise points and outliers in the point cloud data, and these abnormal points often seriously affect the accuracy and reliability of the fitting results. The basic idea of the least squares method is to determine the optimal fitting parameters by minimizing the squared error between the fitting curve and all data points. However, during the actual collection of point cloud data, due to factors such as sensor accuracy, environmental interference, and object surface characteristics, it often contains a large amount of noise and outliers. These abnormal points not only can raise or lower the parameter estimation values of the fitting curve, but may also cause the overall fitting curve to deviate from the true shape, thereby affecting subsequent analysis and applications. For example, in industrial inspection, accurate circular fitting is crucial for detecting the geometric accuracy of workpieces, and the presence of noise points and outliers may lead to misjudgments and affect product quality control. There are several drawbacks in bridge flaw detection technology: (1) Traditional bridge detection methods mainly rely on manual inspections, which are inefficient and easily affected by human factors, making it difficult to ensure the accuracy and consistency of detection results. In addition, manual detection takes a long time and is difficult to cover a large range of bridge structures, especially in high-risk or complex areas, where the detection work is even more difficult. (2) Existing detection technologies have limitations in identifying micro-cracks or hidden damages. Many subtle structural defects are difficult to detect in a timely manner through conventional detection means, resulting in potential safety hazards not being effectively warned. At the same time, some advanced non-destructive testing technologies such as ultrasonic and infrared thermography are costly and complex to operate, limiting their widespread application. (3) The real-time monitoring ability of bridges is insufficient, and traditional detection methods are difficult to achieve continuous and dynamic structural health monitoring. This makes it impossible to respond and handle emergencies in a timely manner when sudden damages occur. In terms of data processing and analysis, existing technologies mostly rely on manual analysis, lacking intelligent and automated support, and it is difficult to quickly and accurately evaluate the overall state of the bridge. (4) Environmental factors such as weather conditions and traffic interference also affect the implementation of detection work and the reliability of results. These deficiencies limit the effectiveness of current bridge flaw detection technologies in ensuring bridge safety and extending service life.

[0055] Based on this, this embodiment provides a method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck, as Figure 1 shown in, the method includes:

[0056] Step S100: Select a single-column pier of a curved bridge section and determine the pier point cloud data of the single-column pier of the curved bridge section;

[0057] Step S200: Determine point cloud slices based on the point cloud density of the pier, and perform deviation analysis of the single-column pier of the curved bridge based on the point cloud slices to obtain the verticality of the pier.

[0058] Step S300: Establish the topological relationship of the bridge deck point cloud, perform surface fitting of the local point cloud of the bridge deck based on the topological relationship of the bridge deck point cloud, and estimate the Gaussian curvature.

[0059] Step S400: Perform damage assessment on the pier and bridge deck based on the pier verticality and the Gaussian curvature to obtain the damage assessment result.

[0060] In this embodiment, through multiple iterations and threshold limitations, outliers in the data are successfully removed, improving the accuracy and reliability of circular fitting. In addition, the Gaussian curvature calculation is based on point cloud data, enabling high-precision three-dimensional surface reconstruction and improving the accuracy and reliability of flaw detection. This method has a high degree of automation. Combining advanced algorithms and machine learning technologies, it can achieve fast and real-time structural health monitoring, improve detection efficiency, and reduce human errors.

[0061] The method for deviation analysis of the single-column pier of the curved bridge and bridge deck damage assessment in this embodiment can be applied to terminals, and the terminals can be intelligent terminal products such as computers, smart TVs, and mobile phones. Specifically in application, the method of this embodiment mainly includes two parts, and its technical route is as Figure 2 shown. The circle fitting algorithm based on the three-point iteration limit threshold for single-phase point cloud is used to realize the analysis of the inclination verticality of the single-column pier of the curved bridge and the damage detection of the bridge deck based on the Gaussian curvature.

[0062] Specifically, in this embodiment, the single-column pier of the curved bridge section is first selected, and the model of the single-column pier of the curved bridge section is denoised to eliminate gross measurement errors and optimize the point cloud data to obtain the pier point cloud data. For the obtained pier point cloud data, the circle fitting method is used to extract the key points of the pier point cloud and the connected feature lines, fit the numerical values into a smooth curve function, and calculate the inclination angle and slope of the pier column through function analysis to judge its inclination trend, specifically as follows:

[0063] 1) Determine the slices according to the density of the single-column pier point cloud

[0064] This embodiment uses hierarchical slice fitting to obtain the central coordinates of each slice, and then fits the center line of the pier to calculate the verticality of the pier. Specifically, data processing can be carried out using Realworks software. Trimble Realworks software has three major functional modules: the Registration module, the Officesurvey module, and the Modeling module. First, use the plane cutting function in the Officesurvey module to obtain the point cloud slices of the pier. Figure 3Schematic diagram of a slice of pier 1 as shown. If the height of pier 1 is 6.5 m, it is stratified at intervals of 0.5 m from the bottom of the pier with a slice thickness of 1 cm to obtain 13 point cloud slices of pier 1. As Figure 4 Display diagram of the point cloud of the slice shown in the overall point cloud. Then, use the Modeling module to model each point cloud slice with a cylinder model to obtain the center coordinates of several slices.

[0065] 2) Export the point cloud coordinates and perform algorithm calculations

[0066] Generally, the number of point clouds completed for a 0.01 m slice is about 800. After thinning in Cloudcompare, generally about 200 point clouds remain. At this time, the coordinates of each point can be exported from the software to obtain a TXT file format, which includes the coordinates, color, and intensity information of each point, as Figure 5 shown in.

[0067] Under the action of the external environment, the surface protective layer of the bridge pier column may fall off, and outliers may occur during the measurement process. In the traditional least squares method, these outliers are not removed, but are counted as sample data for unified fitting. In this way, there are certain errors in the fitted center coordinates. To reduce this error, the following algorithm is designed to remove outliers and fit the parameters of the circular curve, combined with Figure 6 shown in, including the following steps:

[0068] (1) Randomly select 3 points from the collected points to calculate the center parameters. Before calculation, it should be judged whether the 3 selected points are on the same straight line.

[0069] (2) Use the parameters calculated in step (1) to construct a circular curve, judge the distance l from each point in the point cloud slice to the circular curve, set a threshold m, and record the number of points n of all points less than this threshold.

[0070] (3) Repeat steps (1) and (2) to traverse all measurement points, find the group with the largest number of points n, record all the point numbers in this group, and then perform least squares fitting based on all the points in the group with the largest number of points.

[0071] In this embodiment, each cross-section of a single-column pier is calculated, retaining the original number of points. The algorithm is used to leave the number of points within the set threshold. The threshold is set to the 0.02 m data used for thinning in riscan pro in the early stage, ensuring that the threshold is not too large to cause inaccurate calculations and not too small to cause a futile increase in calculation time and calculation amount. Just setting it at the size of the average distance between each point can solve the accurate center coordinates with the highest efficiency. Table 1 below will show the number of points used for calculation, the proportion of effective point clouds, and the center coordinates after the threshold.

[0072] Calculation Results of Each Cross-Section Algorithm for Single-Pier

[0073]

[0074] As can be seen from Table 1 above, the proportion of the finite point cloud is basically above 50%, ensuring the calculation accuracy while maximizing the calculation efficiency. The visualization of the specific algorithm part of the sliced diagram is as shown in Figure 7 shown Figure 7 The left figure in Figure 7 is the circular coordinate of section number 5 of Pier No. 9,

[0075] 3) Verification of Calculation Result Accuracy

[0076] By comparing the offsets in the x and y directions and the overall offset and perpendicularity obtained by using the software slicing method to model and directly calculating the circular curve parameters by the least squares method. The definition of perpendicularity is: when the height of the pier increases by 1 m, the deviation of the pier center in the horizontal direction is the perpendicularity of the pier. At this time, ΔX represents the offset in the x direction, ΔY represents the offset in the y direction, ΔXY is the total inclination, and the perpendicularity of the pier is:

[0077] Δ x = |x2 - x1| (1.1)

[0078] Δ y = |y2 - y1| (1.2)

[0079]

[0080] Based on the above calculation formulas, the offset and perpendicularity of the pier can be calculated. In this embodiment, fitting the values of the pier offset and perpendicularity with the height can obtain the relationship between the inclination of the single-pier and the height as shown in Figure 8 and the relationship between the perpendicularity of the single-pier and the height as shown in Figure 9 shown

[0081] The Mean Squared Error (MSE) is a commonly used indicator to evaluate the performance of a prediction model and is used to measure the difference between the predicted value and the actual observed value. The specific definition is as follows:

[0082]

[0083] where: n represents the number of samples; y i is the value of the i-th sample; is the predicted value of the i-th sample

[0084] Based on the fact that the order of magnitude of the mean square error calculated above is much smaller than that of the ordinary slicing method and the method without removing discrete points and noise, and the distribution of the fitted straight line is also more uniform. Therefore, the circle fitting algorithm based on the three-point iterative limit threshold proposed in this embodiment is a more innovative and accurate method. The circle fitting algorithm based on the three-point iterative limit threshold for single-period point cloud proposed in this embodiment provides an effective solution to the deficiencies of the traditional least squares method in dealing with noise and outliers. Through multiple iterations and threshold limitations, this algorithm successfully removes the outliers in the data, improving the accuracy and reliability of circular fitting.

[0085] The above is the deviation analysis of the pier. For the bridge deck, this patent proposes a method for detecting bridge deck damage based on Gaussian curvature. A curved surface is a moving line, which is the representation of the trajectory of continuous movement in space, and curvature is the description of the degree of bending of the curved surface. Gaussian curvature is defined as the significant differential component of a twice-differentiable surface and is an inherent quantity of the surface. If the curved surface is affected by regular bending or other isometric transformations (i.e., continuous invertible transformations and their inverse transformations are differentiable together), the Gaussian curvature remains unchanged. However, when the bridge is damaged, the internal Gaussian curvature will change abnormally. Utilizing the above characteristics, in the detection of the deformation of the bridge curved surface in this paper, based on the mutation of the Gaussian curvature value, the damage location and degree of the bridge curved surface are presented in a visual way. However, in the actually collected point cloud data, there are often more noise interferences, affecting the accuracy of the data. Therefore, a suitable Gaussian curvature estimation method is selected to suppress the noise to the greatest extent.

[0086] (1) Method for establishing point cloud topological relationship

[0087] Point cloud topological relationship refers to the adjacent, tangent, separated, and inclusion relationships between geometric elements such as points, lines, and surfaces to describe objects. The advantages of generating topology are: (1) Using the topological relationship, without calculating coordinates and distances, the positional relationship between two three-dimensional objects in the same space can be determined. (2) Through the topological relationship, elements in the same data set can be found; (3) Geometric bodies are generated according to the topological relationship, such as generating circles according to curvature, generating geometric bodies by connecting points with points, etc.

[0088] Topological relations can reflect the positional and structural relationships between objects and do not change due to different observation dimensions. A topological relation stores three parameters: rules, levels, and topological tolerance. Rules define the spatial form of the topology and determine the mutual relationships of various elements. Topology can only be generated under more than one topological rule. Levels specify the movement from lower-level elements to higher-level elements. When generating topological relations, it is necessary to classify the elements. Topological tolerance reflects the minimum amount of nodes and geometric edges that can be searched within a certain spatial size. The size of the topological tolerance depends on the data, and the initial topological tolerance value is calculated by the system based on the relationships between the data. The point cloud data information obtained by three-dimensional detection devices such as radar, laser scanners, and stereo cameras often has characteristics such as large amounts of information and uneven distribution. The lack of topological association between points is irregular point cloud. In point cloud data processing, such as filtering, segmentation, and curvature calculation, etc., generally, a neighborhood is established to classify and summarize the surrounding point cloud to achieve the effect of quickly finding adjacent points, which is also an important value for establishing the topological relationship of point cloud.

[0089] Generally, there are two methods to construct a neighborhood: ① KD-Tree algorithm, ② three-dimensional grid method. Although the working principle of the three-dimensional grid technology is relatively simple and easy to understand, it is not very convenient to use in practice, especially when dealing with large amounts of data and uneven density distribution, the processing effect is not good. Defining the length of the boundary in a small grid is a major problem. Because if the boundary is large, it will accommodate a larger amount of point cloud data, which is very likely to cause data redundancy and increase the computational workload. While choosing a too-small boundary will generate a larger number of grids, which will have a certain impact on the final stitching. Due to the characteristics of the bridge point cloud itself, the collected point cloud is disordered, and the density of the point cloud does not change evenly, as Figure 10 shown in the figure, so in this embodiment, the KD-Tree is preferentially selected to establish the topological relationship of the point cloud.

[0090] (2) Surface fitting of local point cloud on the bridge deck

[0091] The normal vector is an attribute of the surface of a geometric body. In point cloud reconstruction algorithms, point cloud segmentation algorithms, point cloud denoising algorithms, and feature description algorithms, better results can be achieved only through accurate normal vectors. For the surfaces of specific objects, it is relatively simple to directly infer the direction of the normal vector at a certain point on the surface, and only the surface where the point is located needs to be found. When studying the local points of a certain surface in this embodiment, its range is larger than that of a single point, thus forming two different solutions: ① Start from the local features of the point cloud set and determine the normal vector of the point according to the searched neighboring points. ② Generate a three-dimensional model of the surface, extract the surfaces in various directions from the three-dimensional model, and then calculate the surface normal from the surface model. Based on the comparison of the topological relationship methods in the previous section, following the first idea, directly perform surface fitting from the scattered point cloud set, analyze according to this situation, obtain a collected point cloud data set, directly estimate the normal vector for each point in this point set, and infer the surface normal. Let be the sampled point cloud set of the lower surface of the bridge. Fit the point cloud data of the lower surface of the bridge to a plane, perform normal estimation of the point cloud. The normal vector can describe the direction of the local surface. The normal vector is one of the important characteristics of the geometric structure of the surface. The schematic diagram of the normal vector Figure 11 is shown as follows.

[0092] Construct candidate point p n For the local coordinate system with as the origin, it is to fit the surface using local point cloud data, which is the prerequisite for calculating the Gaussian curvature. The XYZ axes of the local coordinate system are the main coordinate axes, and the solution of this coordinate axis is the solution of the coordinate system direction of the candidate point. In the K-neighborhood, use the moving least squares method to fit the plane. The core idea of the moving least squares method is to generate a plane from the obtained point cloud set, and use the mathematical formula of the distance from the point to the plane to obtain the normal line perpendicular to the plane for each point, so that the sum of the squares of the distances from all points in the point set to the plane is the smallest. Use the normal vector of the fitted plane as the normal vector of candidate point p n .

[0093] (3) Estimation of Gaussian curvature based on normal vector constraint

[0094] Use the normal vector obtained by fitting the point cloud data of the lower surface of the bridge to a plane as the vertical axis of the coordinate, and perform rotation and translation respectively based on this as the benchmark to obtain the plane where it is located. At this time, the establishment of the temporary coordinate system where the candidate point is located is completed. Using the temporary coordinate system as the reference coordinate system, estimate the Gaussian curvature on the reference coordinate system. The Gaussian curvature is one of the main bases for reflecting the state of the point cloud on the lower surface of the bridge. According to the definition of differential geometry: where the conversion relationships between the first fundamental quantity and the second fundamental quantity are respectively:

[0095]

[0096] Among them:

[0097] r uu, r uv , r vv are the second-order derivatives of the parametric surface respectively;

[0098] r v , r w are the first-order derivatives of the parametric surface;

[0099] EG - F 2 is the discriminant of the first fundamental form.

[0100] According to Rodrigues' theorem, it can be calculated that

[0101]

[0102] The eigenvalues λ of this matrix correspond to the principal curvatures.

[0103] By calculating this second-order determinant, it can be obtained that:

[0104] (EG - F 2 )λ 2 -(LG - 2MF + NE)λ+(LN - M 2 ) = 0 (1.10)

[0105] Since the coefficient of the quadratic term is always greater than zero, this equation can be simplified to a quadratic equation in one variable. Using Vieta's theorem to solve it, the two roots are the two principal curvatures of the surface. The principal curvature is the maximum and minimum values of the curvature of the surface at this point, which are respectively:

[0106]

[0107] The product of the principal curvatures is the Gaussian curvature of the surface at this point, that is:

[0108]

[0109] It can be seen that the Gaussian curvature actually reflects the degree of curvature change of the lower surface of the bridge. If there is no potential damage area on the bridge, the Gaussian curvature is invariant. Therefore, when evaluating the damage of the pier and bridge deck, if the Gaussian curvature shows a sudden change, it means that there has been a great change in the lower surface of the bridge, and at the same time, it indicates the existence of a potential damage area. At this time, the potential damage area can be determined. If there is an overall curvature change in a certain area, it indicates obvious deformation or deflection at that place. The Gaussian curvature calculation is based on the point cloud data of the pier, which can achieve high-precision three-dimensional surface reconstruction, improve the accuracy and reliability of flaw detection. In this embodiment, the verticality of the pier and the Gaussian curvature of the pier and bridge deck are evaluated. The damage identification and evaluation of the pier and bridge deck can be carried out by combining the verticality of the pier and the Gaussian curvature, which can realize fast and real-time structural health monitoring, improve the detection efficiency, and reduce manual errors.

[0110] Based on the above embodiments, the present invention further provides a system for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck, as follows Figure 12 As shown in Figure 12 , the system includes: a point cloud data determination module 10, a pier inclination analysis module 20, a bridge deck curvature detection module 30, and a bridge deck damage evaluation module 40. Specifically, the point cloud data determination module 10 is configured to select a single-column pier of a curved bridge section and determine the pier point cloud data of the single-column pier of the curved bridge section. The pier inclination analysis module 20 is configured to determine point cloud slices according to the point cloud density for the pier point cloud data, and perform deviation analysis of the single-column pier of the curved bridge based on the point cloud slices to obtain the pier verticality. The bridge deck curvature detection module 30 is configured to establish a topological relationship of the bridge deck point cloud, perform surface fitting of the local point cloud of the bridge deck based on the topological relationship of the bridge deck point cloud, and estimate the Gaussian curvature. The bridge deck damage evaluation module 40 is configured to perform damage evaluation on the pier and the bridge deck based on the pier verticality and the Gaussian curvature to obtain a damage evaluation result.

[0111] In the system for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck in this embodiment, the working principles of each module are the same as those of each step in the above method embodiment, and will not be elaborated here.

[0112] Each module in the above system for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck can be implemented in whole or in part by software, hardware, and their combination. Each of the above modules can be embedded in or independent of a processor in the terminal in the form of hardware, or stored in a memory in the terminal in the form of software, so as to facilitate the processor to call and execute the operations corresponding to each of the above modules.

[0113] Based on the above embodiments, the present invention further provides a terminal, and the principle block diagram of the terminal can be as follows Figure 13 As shown in Figure 13 . The terminal may include one or more processors 100 ( Figure 13 only one is shown in Figure 13 ), a memory 101, and a computer program 102 stored in the memory 101 and executable on one or more processors 100.

[0114] In one embodiment, the so-called processor 100 may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0115] In one embodiment, the memory 101 may be an internal storage unit of the electronic device, such as the hard disk or memory of the electronic device. The memory 101 may also be an external storage device of the electronic device, such as a plug-in hard disk equipped on the electronic device, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. Further, the memory 101 may also include both an internal storage unit and an external storage device of the electronic device. The memory 101 is used to store computer programs and other programs and data required by the terminal. The memory 101 may also be used to temporarily store data that has been output or is to be output.

[0116] Those skilled in the art can understand that Figure 13 the principle block diagram shown in

[0117] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, operational database, or other medium used in the embodiments provided by the present invention can include non-volatile and / or volatile memories. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck, characterized in that The method includes: Selecting a single-column pier of a curved bridge section and determining the pier point cloud data of the single-column pier of the curved bridge section; Determining point cloud slices based on the point cloud density of the pier point cloud data, and performing offset analysis of the single-column pier of the curved bridge based on the point cloud slices to obtain the pier verticality; Establishing a topological relationship of the bridge deck point cloud, performing surface fitting of the local point cloud of the bridge deck based on the topological relationship of the bridge deck point cloud, and estimating the Gaussian curvature; Performing damage assessment on the pier and bridge deck based on the pier verticality and the Gaussian curvature to obtain a damage assessment result.

2. The curve bridge single-column pier deviation analysis and bridge deck damage assessment method according to claim 1, characterized in that The selection of the single-column pier of the curved bridge section and the determination of the pier point cloud data of the single-column pier of the curved bridge section include: Selecting a single-column pier of a curved bridge section, denoising the model of the single-column pier of the curved bridge section, removing gross measurement errors, and optimizing the point cloud data to obtain the pier point cloud data.

3. The method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck according to claim 1, wherein The determination of point cloud slices based on the point cloud density of the pier point cloud data and the offset analysis of the single-column pier of the curved bridge based on the point cloud slices to obtain the pier verticality include: Based on the plane cutting function in the Officesurvey module of Realworks software, obtaining the point cloud slices of the pier, and using the Modeling module of Realworks software to model a cylinder model for each point cloud slice to obtain the coordinates of several slice centers; Based on the coordinates of the section centers, removing outliers and fitting the parameters of the circular curve, and calculating the pier offset and the pier verticality.

4. The method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck according to claim 3, characterized in that Based on the coordinates of the section centers, removing outliers and fitting the parameters of the circular curve include: Randomly selecting 3 points and determining whether the 3 selected points are on the same straight line; Constructing a circular curve based on the 3 selected points, determining the distance from each point in the point cloud slice to the circular curve, and obtaining the number of all points less than a preset threshold; Traversing all measurement points, finding the group with the largest number of points, and performing least squares fitting based on all points in the group with the largest number of points.

5. The method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck according to claim 1, wherein, Performing surface fitting of the local point cloud of the bridge deck based on the topological relationship of the bridge deck point cloud and estimating the Gaussian curvature include: Obtaining the point cloud set of the lower surface of the bridge, performing plane fitting on the point cloud data of the lower surface of the bridge, and performing normal estimation of the point cloud to obtain a normal vector, where the normal vector is used to describe the direction of the local surface of the bridge deck; Taking the normal vector obtained by performing plane fitting on the point cloud data of the lower surface of the bridge as the vertical axis of the coordinate, and performing rotation and translation respectively based on this as a reference to establish a temporary coordinate system; Taking the temporary coordinate system as the reference coordinate system, and estimating the Gaussian curvature on the reference coordinate system.

6. The method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck according to claim 3, characterized in that The method further includes: Fitting the pier verticality and the pier offset with the height respectively to determine the relationship between the verticality and the height of the single-column pier of the curved bridge, and the relationship between the inclination of the single-column pier of the curved bridge and the height.

7. The method for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck according to claim 1, wherein The damage assessment of the pier and bridge deck based on the pier verticality and the Gaussian curvature to obtain a damage assessment result includes: If the Gaussian curvature shows a sudden change, determining that the degree of curvature change is large and determining the potential damage area.

8. A system for analyzing the deviation of a single-column pier of a curved bridge and evaluating the damage of the bridge deck, characterized in that, The system includes: A point cloud data determination module for selecting a single-column pier of a curved bridge section and determining the pier point cloud data of the single-column pier of the curved bridge section; The pier inclination analysis module is used to determine point cloud slices for the pier point cloud data according to the point cloud density, and perform offset analysis on the single-column pier of the curved bridge based on the point cloud slices to obtain the pier verticality; The bridge deck curvature detection module is used to establish the topological relationship of the bridge deck point cloud, perform surface fitting on the local point cloud of the bridge deck based on the topological relationship of the bridge deck point cloud, and estimate the Gaussian curvature; The bridge deck damage assessment module is used to perform damage assessment on the pier and bridge deck based on the pier verticality and the Gaussian curvature to obtain a damage assessment result.

9. A terminal, characterized in that, The terminal includes a memory, a processor, and a curved bridge single-column pier offset analysis and bridge deck damage assessment program stored in the memory and executable on the processor. When the processor executes the curved bridge single-column pier offset analysis and bridge deck damage assessment program, the steps of the curved bridge single-column pier offset analysis and bridge deck damage assessment method according to any one of claims 1-7 are implemented.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a curved bridge single-column pier offset analysis and bridge deck damage assessment program. When the curved bridge single-column pier offset analysis and bridge deck damage assessment program is executed by a processor, the steps of the curved bridge single-column pier offset analysis and bridge deck damage assessment method according to any one of claims 1-7 are implemented.

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