Method and system for detecting deformation quantity and curvature of tower main material based on three-dimensional laser point cloud

Abstract

The invention provides a tower main material deformation quantity and curvature detection method and system based on a three-dimensional laser point cloud, and the method comprises the steps: firstly carrying out the multi-angle scanning of a power transmission tower through a three-dimensional laser scanner, extracting a tower point cloud, and then carrying out the noise reduction filtering; performing orientation and rotation on the tower point cloud by adopting a PCA algorithm; performing horizontal slice projection on the tower, and extracting the point cloud of the quadrangular frustum pyramid part of the tower body through the length-width ratio, the area ratio and the point number of point cloud slices; respectively calculating four vertexes of each layer of slice of the quadrangular frustum pyramid, and then calculating the distance from the vertex of each layer of slice to the connecting line of the end points of the main material; whether a slope change point exists or not is judged through the slope change of the vertex of the principal material, and the quadrangular frustum pyramid slices above the slope change point are removed; and finally, the deformation quantity, the bending degree and the position of the main material are obtained through calculation. The method has the advantages of being high in measurement precision, small in labor amount and the like, and effectively solves the technical problem that the deformation quantity, the bending degree and the position of the tower main material are difficult to measure.

Description

Technical Field

[0001] The present invention relates to the field of abnormal detection of transmission line tower structures, and specifically to a method and system for detecting the shape change amount and bending degree of the main members of a tower based on three-dimensional laser point cloud, which is applicable to the detection of the main member parameters of angle steel towers. Background Technique

[0002] Since transmission lines extend for hundreds to thousands of kilometers, are widely distributed geographically, and have a harsh external environment, they are extremely vulnerable to the influence of extremely severe natural disasters. Under the action of harsh working conditions such as ice coating and galloping, extreme strong winds, and geological disasters, transmission line towers are prone to local deformation of the main members due to factors such as unbalanced loads, over-design loads, and foundation displacement and settlement, which may further cause equipment damage accidents such as tower overturning, threatening the safe operation of the line. Timely detection of the deformation and bending degree of the main members of the tower is extremely important for the safe and stable operation of the line.

[0003] The invention patent with publication number CN115810012B discloses a method, device, equipment, and storage medium for detecting the inclination of a transmission tower. It includes: obtaining a plurality of initial point cloud data for the space where the transmission tower to be detected is located; solving the geometric features of each initial point cloud data to obtain the geometric feature information corresponding to each initial point cloud data, and based on the geometric feature information, obtaining the target point cloud data corresponding to each initial point cloud data; from the target point cloud data, obtaining the transmission tower point cloud data corresponding to the transmission tower and the ground point cloud data corresponding to the ground where the transmission tower is located; and obtaining the inclination detection result corresponding to the transmission tower based on the transmission tower point cloud data and the ground point cloud data. This method is applicable to extracting the tower point cloud from the transmission line point cloud and then calculating the inclination of the tower.

[0004] The invention patent with publication number CN115880276A discloses a method for evaluating the operating state of a tower pole based on multi-period point cloud comparison. A three-dimensional cone is established according to the tower pole point cloud to obtain the inclination angle. Based on the inclination angle and the inclination degrees of multiple tower poles, the operating state of the tower pole is obtained. Information is extracted using a two-dimensional convolution kernel from the front and side and using a three-dimensional convolution kernel from the top to respectively judge the inclination degree of the tower pole, so that not only can the shape information of the tower pole be accurately obtained from the front and side, but also the overall inclination degree can be judged from the top to break through the cutting angle problem.

[0005] In summary, the existing methods mainly use 3D laser point clouds to identify the overall inclination of transmission towers, and evaluate the operating status of transmission towers based on this. However, specifications such as the "Code for Operation of Overhead Transmission Lines" (DL / T 741-2019) and the "Code for Construction and Acceptance of 110 kV - 750 kV Overhead Transmission Lines" (GB 50233-2014) all require the detection of the bending degree of the main members of transmission towers, and it is difficult for existing technologies to effectively carry out the detection of the bending degree of the main members of transmission towers. In order to improve the detection means for abnormal tower structures, the present invention uses 3D laser scanning technology to perform multi-angle fine scanning on transmission towers, proposes an automatic extraction algorithm for the deformation amount and bending degree of the main members of transmission towers, and realizes the accurate measurement of the deformation amount, bending degree and their positions of the main members of transmission towers. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the present invention provides a method and system for detecting the deformation amount and bending degree of the main members of transmission towers based on 3D laser point clouds, which can be used to measure the stress yield deformation amount and deformation position of the main members of transmission towers caused by external loads, and then obtain the bending degree of the main members.

[0007] A method for detecting the deformation of the main members of a transmission tower based on 3D laser point clouds includes the following steps:

[0008] Step 1: Perform multi-angle scanning on the transmission tower through a ground 3D laser scanner to obtain the tower point cloud, and perform noise reduction processing on the tower point cloud;

[0009] Step 2: Use the PCA algorithm to orient and rotate the noise-reduced tower point cloud;

[0010] Step 3: Perform horizontal slice projection on the oriented and rotated tower point cloud along the height direction of the tower, and extract the point cloud data of the quadrangular frustum of the tower body according to the aspect ratio, area ratio and number of slice points of each layer of slices;

[0011] Step 4: Based on the point cloud data of the quadrangular frustum, calculate the coordinates of the four vertices of each layer of horizontal slices respectively;

[0012] Step 5: According to the coordinates of the four vertices, calculate the vertical distance from the vertex of each layer of slice to the line connecting the endpoints of the main member;

[0013] Step 6: Determine whether there is a slope change point by analyzing the slope change of the vertex distances of each layer of slices, and remove the quadrangular frustum slices corresponding to the upper part of the slope change point;

[0014] Step 7: Based on the remaining vertex coordinates of the quadrangular frustum slices, calculate the deformation amount, bending degree and their position information of the main member.

[0015] Further, the step 3 includes:

[0016] Step 3.1, Calculation of tower point cloud slice parameters: Use a set of planes with a thickness of δ to intersect the point cloud, slice the point cloud from bottom to top to obtain the point cloud slice S i , and then project each layer of point cloud slices onto a horizontal plane to obtain the projection slice S i '. Calculate the side lengths l ix , l iy , area s i , and number of points n i of each layer of point cloud slices respectively, and then calculate the area of the circumscribed rectangle and the aspect ratio

[0017] Step 3.2, Extraction of the four-sided frustum structure of the tower body: According to the tower structure determination criterion, extract the four-sided frustum structure of the tower body, denoted as S i , i = 1, 2, … m, and the determination criterion is: ① The area of the circumscribed rectangle of the slice is continuous and there is no mutation layer, and the slice area ratio satisfies: where s i is the area of the circumscribed rectangle of the projection S i ' of the i-th layer slice; ② The aspect ratio of the circumscribed rectangle of the section plane satisfies: where l ix , l iy are the length and width of the circumscribed rectangle of the projection S i ' of the i-th layer slice; ③ The number of points n i of the slice should be greater than 1000.

[0018] Furthermore, the said step 4 includes:

[0019] Step 4.1, Extract the vertices A and C of the four-sided frustum slice: Perform the following operations on the points in each layer of the four-sided frustum slice point cloud S i , i = 1, 2, … m. Taking S i as an example, the point cloud coordinates in S i are (x i , y i , z i ), i = 1, 2, … n. Calculate x i + y i , i = 1, 2, … n respectively, extract min(x i + y i ) and max(x i + y i ), extract k minimum values and maximum values in sequence, take the average of the coordinates of the k points, the minimum value is denoted as point A, and its coordinates are the maximum value is denoted as point C, and its coordinates are

[0020] Step 4.2, extract the vertices B and D of the frustum slice: For the point cloud S of each frustum slice i , i = 1, 2, … m, perform the following operations on the midpoints, taking S i as an example. Rotate S i counterclockwise by 90°. Repeat the above steps to obtain points B and D respectively, and their coordinates are

[0021] Step 4.3, obtain the vertex coordinates of the frustum: Merge the vertices of the m-layer point cloud slices to obtain the vertex coordinates of the frustum slice, denoted as A i , B i , C i , D i , i = 1, 2, … m.

[0022] Furthermore, the said Step 5 includes:

[0023] Step 5.1, calculate the distance from the vertex of the main material in Group A to the end point of the main material: The vertices of the main material in Group A are A i , i = 1, 2, … m, and their coordinates are (x A.i , y A. , z A.i ), i = 1, 2, … m, where the end point coordinates are A1(x A.1 , y A.1 , z A.1 ) and A m (x A.m , y A.m , z A.m ). Taking the triangle formed by A i (x A.i , y A.i , z A.i ) and the end points as an example, calculate the distance from A i to the line connecting A1 and A m . The steps are as follows:

[0024] Calculate the lengths of each side A1A m , A1A i , A i A m . The semi-perimeter is:

[0025]

[0026] The area s of the triangle is:

[0027]

[0028] The distance from A i to the line connecting A1 and A m is:

[0029]

[0030] Step 5.2, calculate the distances from the vertices of the main materials in groups B, C, and D to the endpoints of the main materials in sequence according to the above steps, and denote them as d A.i , d B.i , d C.i , d D.i , i = 1, 2, … m.

[0031] 10. Further, the said step 6 includes:

[0032] Step 6.1, perform differencing on the distances d A.i , d B.i , d C.i , d D.i , i = 1, 2, … m of the four main materials A, B, C, and D:

[0033]

[0034] Step 6.2, set the points where the difference of the distances of the four main materials is less than 0 to 1, and the points greater than 0 to 0:

[0035]

[0036] Step 6.3, sum up the above four groups of values:

[0037]

[0038] Step 6.4, when the offsets of three groups of main materials continuously decrease, that is , determine that the k-th layer is the slope-changing point, denote it as m' = k, and remove the point cloud slice above the slope-changing point.

[0039] Further, the said step 7 includes:

[0040] According to step 5, calculate the distances d' from the vertices A i , B i , C i , D i , i = 1, 2, … m' of the main materials in groups A, B, C, and D to the endpoints A i , B i , C i , D i , i = 1, m' of the connecting lines in sequence, where the height (z A.i , d' B.i , d' C.i , d' D.i , i = 1, 2, … m', among which, the height of the slice where the deformation of the main material is located (z A.i , z B.i , z C.i , zD.i ) is the deformation position;

[0041] Calculate the bending degree of the main material according to the following formula:

[0042]

[0043] In the formula, the slice layer where the maximum value of the main material deformation amount is located is (A.max.i, B.max.i, C.max.i, D.max.i), and the height (z A.max.i , z B.max.i , z C.max.i , z D.max.i ) is the position of the maximum deformation rate.

[0044] A detection system for the deformation amount and bending degree of the main material of a transmission tower based on three-dimensional laser point cloud, comprising: a computer-readable storage medium and a processor;

[0045] The computer-readable storage medium is used to store executable instructions;

[0046] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the method for detecting the deformation amount and bending degree of the main material of the transmission tower based on three-dimensional laser point cloud.

[0047] A non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method for detecting the deformation amount and bending degree of the main material of the transmission tower based on three-dimensional laser point cloud is implemented.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] (1) Compared with the prior art, the present invention solves the technical problem of difficult measurement of the bending degree of the main material of the transmission tower, and has the advantages of high measurement accuracy and small workload. The present invention uses three-dimensional laser scanning technology to scan the transmission tower of the transmission tower from multiple angles, automatically extracts the deformation amount of the main material and the position of the maximum deformation through an algorithm, and then obtains the bending degree of the main material, which can solve the problems of low measurement efficiency and large workload of existing measurement technologies such as total station.

[0050] (2) Compared with the prior art, the present invention helps to solve the risk determination of the deformation of the transmission tower structure caused by harsh working conditions such as geological disasters, ice-covered galloping, and extreme strong winds. Existing technologies such as manual visual inspection and visible light inspection by unmanned aerial vehicles are difficult to detect structural anomalies such as bending of the main material of the transmission tower in time. The present invention scans and detects the transmission tower after being subjected to extremely harsh working conditions through three-dimensional laser scanning technology, accurately extracts structural anomalies such as bending of the main material of the transmission tower, and helps technicians to timely discover the structural damage of the transmission tower. Description of the Drawings

[0051] Figure 1It is the flow chart of the method for detecting the deformation amount and bending degree of the main tower materials based on 3D laser point cloud in the present invention;

[0052] Figure 2 It is the tower pole point cloud after filtering in the embodiment of the present invention;

[0053] Figure 3 In (a), it is the side view schematic diagram after PCA orientation and coordinate transformation of the tower pole point cloud in the embodiment of the present invention; (b) is the top view schematic diagram after PCA orientation and coordinate transformation of the tower pole point cloud in the embodiment of the present invention;

[0054] Figure 4 It is the schematic diagram of the tower pole point cloud slice projection in the embodiment of the present invention;

[0055] Figure 5 It is the schematic diagram of the extraction of the four-sided prism of the tower body in the embodiment of the present invention;

[0056] Figure 6 In (a), it is the schematic diagram of the extraction of the slice vertices of the four-sided prism of the tower body; (b) is the schematic diagram of the extraction of the slice vertices of the four-sided prism of the main material;

[0057] Figure 7 It is the extraction result of the bending degree of the main material in the embodiment of the present invention;

[0058] Figure 8 It is the schematic diagram of the measuring points of the total station instrument in the embodiment of the present invention. Detailed implementation manners

[0059] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the accompanying drawings in the present invention.

[0060] The present invention first uses a ground 3D laser scanner to scan a certain hidden danger tower pole from multiple angles, extracts the tower pole point cloud and then performs noise reduction filtering; uses the PCA algorithm to orient and rotate the tower pole point cloud; according to the tower pole structure determination criterion, extracts the four-sided prism structure of the tower body, calculates the four vertices of each layer slice of the four-sided prism, and respectively calculates the distances from the vertices of each layer slice to the end points of the main material; identifies whether there are slope change points through the slope change, and eliminates the four-sided prism slices above the slope change points; finally, calculates the deformation amount, bending degree and their positions of the main material, as shown in Figure 1 . The specific implementation steps are as follows:

[0061] Step 1: Use a ground 3D laser scanner to scan a transmission tower pole from multiple angles to obtain the tower pole point cloud, and perform noise reduction processing on the tower pole point cloud; specifically, use a ground 3D laser scanner to perform a scanning detection on a certain hidden danger tower pole, set up 3 stations around the transmission tower pole at equal angles, and control the angle between the station and the tower pole to be about 120°. Extract the tower pole point cloud from the measured point cloud, and then perform noise reduction filtering on the point cloud tower pole to obtain the tower pole point cloud S, as shown in Figure 2 shown.

[0062] Step 2: Orient and rotate the noise-reduced tower point cloud using the PCA algorithm. Specifically, perform PCA orientation on the tower head part of the tower point cloud to obtain the main direction vector and its direction angle of the tower point cloud; then rotate the tower point cloud around the z-axis. The tower point cloud is denoted as S', as Figure 3 shown.

[0063] Step 3: Perform horizontal slice projection on the oriented and rotated tower point cloud along the tower height direction, and extract the point cloud data of the four-sided frustum of the tower body according to the length-width ratio, area ratio, and number of slice points of each layer of slices;

[0064] The specific implementation process of Step 3 is as follows:

[0065] Step 3.1: Calculate the slice parameters of the tower point cloud. Use a set of planes with a thickness of δ to intersect with the point cloud, slice the point cloud from bottom to top to obtain the point cloud slice S i , and then project each layer of point cloud slices onto a horizontal plane to obtain the projection slice S i '. Calculate the side lengths l ix , l iy , area s i , and number of points n i of each layer of point cloud slices respectively, and then calculate the area of the circumscribed rectangle and the length-width ratio

[0066] Step 3.2: Extract the four-sided frustum structure of the tower body. According to the tower structure determination criterion, extract the four-sided frustum structure of the tower body, denoted as S i , i = 1, 2, … m. The determination criterion is as follows: ① The area of the circumscribed rectangle of the slice is continuous and there is no sudden change layer, and the slice area ratio satisfies: where s i is the area of the circumscribed rectangle of the projection S i ' of the i-th layer slice; ② The length-width ratio of the circumscribed rectangle of the section plane satisfies: where l ix , l iy are the length and width of the circumscribed rectangle of the projection S i ' of the i-th layer slice; ③ The number of slice points n i should be greater than 1000.

[0067] In this embodiment, the tower point cloud S' is horizontally sliced according to the slice thickness δ = 80 cm and then projected onto a horizontal plane. The number of slice layers is 71 layers, as Figure 4 ; the four-sided frustum structure of the tower body is extracted according to the "tower four-sided frustum structure determination criterion", and the number of four-sided frustum slices is m = 50 layers, as Figure 5 .

[0068] Step 4: Calculate the coordinates of the four vertices of each horizontal slice based on the point cloud data of the frustum of a pyramid. The specific implementation process of Step 4 is as follows:

[0069] Step 4.1, Extract the vertices A and C of the frustum of a pyramid slice. Perform the following operations on the midpoints of the point cloud S i , i = 1, 2, … m of each layer of the frustum of a pyramid slice. Taking S i as an example, the midpoint cloud coordinates of S i are (x i , y i , z i ), i = 1, 2, … n. Calculate x i +y i , i = 1, 2, … n respectively, extract min(x i +y i ) and max(x i +y i ). Extract k minimum values and maximum values in sequence. Take the average of the coordinates of the k points. Denote the minimum value as point A, and its coordinates are Denote the maximum value as point C, and its coordinates are

[0070] Step 4.2, Extract the vertices B and D of the frustum of a pyramid slice. Perform the following operations on the midpoints of the point cloud S i , i = 1, 2, … m of each layer of the frustum of a pyramid slice. Taking S i as an example, rotate S i counterclockwise by 90°. Repeat the above steps to obtain points B and D respectively, and their coordinates are

[0071] Step 4.3, Obtain the vertex coordinates of the frustum of a pyramid. Merge the vertices of the m-layer point cloud slices to obtain the vertex coordinates of the frustum of a pyramid slice, denoted as A i , B i , C i , D i , i = 1, 2, … m.

[0072] In this embodiment, calculate the maximum / minimum values of the slice point cloud coordinates (x + y), extract the 4 vertices A i , B i , C i , D i coordinates of each layer of the frustum of a pyramid slice, take the average of the coordinates of k extreme points as the vertices of each layer of the slice (k = 5), and divide the slice vertices into four groups A i , B i , C i , D i , i = 1, 2, … 50, as shown in Figure 6 (a) below.

[0073] Step 5. Calculate the vertical distance from the vertices of each layer slice to the connecting line of the main material endpoints. The specific implementation process of Step 5 is as follows:

[0074] Step 5.1. Calculate the distance from the vertices of the main material in Group A to the endpoints of the main material. The vertices of the main material in Group A are A i , i = 1, 2, … m, and their coordinates are (x A.i , y A. , z A.i ), i = 1, 2, … m. Among them, the endpoint coordinates are A1(x A.1 , y A.1 , z A.1 ) and A m (x A.m , y A.m , z A.m ). Taking the triangle formed by A i (x A.i , y A.i , z A.i ) and the endpoints as an example, calculate the distance from A i to the connecting line of A1 and A m . The steps are as follows:

[0075] Calculate the lengths of each side A1A m , A1A i , A i A m . The semi-perimeter is:

[0076]

[0077] The area s of the triangle is:

[0078]

[0079] The distance from A i to the connecting line of A1 and A m is:

[0080]

[0081] Step 5.2. According to the above steps, calculate the distances from the vertices of the main materials in Groups B, C, and D to the endpoints of the main materials in turn, denoted as d A.i , d B.i , d C.i , d D.i , i = 1, 2, … m.

[0082] In this embodiment, calculate the vertices A i , B i , C i , D of the main materials in Groups A, B, C, and D in turn.i , for \(i = 1, 2, \cdots, 50\), the distance from the main material end point A i , B i , C i , D i , for \(i = 1, 50\), the distance \(d\) A.i , \(d\) B.i , \(d\) C.i , \(d\) D.i , for \(i = 1, 2, \cdots, 50\), as Figure 6 shown in (a).

[0083] Step 6: Determine whether there is a slope change point by analyzing the slope change of the vertex distances of each layer of slices, and eliminate the frustum slices corresponding to the upper part of the slope change point; the specific implementation process of Step 6 is as follows:

[0084] Step 6.1, perform differencing on the distances \(d\) of the four main materials A, B, C, and D A.i , \(d\) B.i , \(d\) C.i , \(d\) D.i , for \(i = 1, 2, \cdots, m\):

[0085] \(\Delta d\) A.i = \(d\) A.i - \(d\) A.(i-1) , for \(i = 1, 2, \cdots, m\) (4)

[0086] \(\Delta d\) B.i = \(d\) B.i - \(d\) B.(i-1) , for \(i = 1, 2, \cdots, m\)

[0087] \(\Delta d\) C.i = \(d\) C.i - \(d\) C.(i-1) , for \(i = 1, 2, \cdots, m\)

[0088] \(\Delta d\) D.i = \(d\) D.i - \(d\) D.(i-1) , for \(i = 1, 2, \cdots, m\)

[0089] Step 6.2, set the points where the difference of the four main material distances is less than 0 to 1, and the points greater than 0 to 0:

[0090]

[0091] Step 6.3, sum the above four groups of values:

[0092]

[0093] Step 6.4, when the offsets of three of the main materials continuously decrease, that is , determine that the \(k\)th layer is a slope change point, denoted as \(m' = k\).

[0094] In this embodiment, the slope change point of the main material is determined according to the continuous change trend of the distance, and the slice layer number m' where the slope change point is located is identified as 30. The point cloud slices above the slope change point are removed, as shown in Figure 6 (b) in

[0095] Step 7: Calculate the deformation amount, bending degree and position information of the main material based on the vertex coordinates of the remaining frustum slices.

[0096] Specifically, according to Step 5, calculate the distances d' from the vertices of the main materials in groups A, B, C, and D to the connection lines of the main material endpoints A i , B i , C i , D i , i = 1, 2, … m' to the connection lines of the main material endpoints A i , B i , C i , D i , i = 1, m', where the height (z A.i , d' B.i , d' C.i , d' D.i , i = 1, 2, … m', and among them, the height (z A.i , z B.i , z C.i , z D.i ) of the slice where the deformation amount of the main material is located is the deformation position, as shown in Figure 7 . Calculate the bending degree of the main material according to the following formula:

[0097]

[0098] In the formula, the slice layer where the maximum value of the deformation amount of the main material is located is (A.max.i, B.max.i, C.max.i, D.max.i), and the height (z A.max.i , z B.max.i , z C.max.i , z D.max.i ) of the slice layer is the position of the maximum deformation rate.

[0099] In this embodiment, according to Step 5, calculate the distances d' from the vertices of the main materials in groups A, B, C, and D to the connection lines of the main material endpoints A.i , d' B.i , d' C.i , d' D.i , i = 1, 2, … 30, as shown in Figure 6As shown in Figure (b). Fit the above distance with a sixth-degree polynomial, and extract the maximum value of the fitted curve and its position. Calculate the main material camber according to formula (7). The main material camber of leg A is 4.55‰ and the height is 10.4 m; the main material camber of leg B is 6.62‰ and the height is 9.6 m; the main material camber of leg C is 4.94‰ and the height is 9.8 m; the main material camber of leg D is 3.57‰ and the height is 10.9 m. For details, see Figure 7 .

[0100] In the traditional method, a total station is generally used to detect the main material camber. Taking the main material of leg A as an example for the measurement method and results, the two endpoints of the main material of leg A are A1 and A2 respectively. The position with the largest deformation of the main material is located at the connection point of the large diagonal member and the main material above the first transverse diaphragm, denoted as A m , and the schematic diagrams of each point are shown in Figure 8 . Since it is difficult for a total station to take points on the main material ridge line, in actual operation, points are taken on the bolts adjacent to the main material ridge line to improve the point-taking accuracy of the total station. Measure the three measuring points according to the above method, and obtain the coordinates of the three measuring points A1, A2, and A m , as shown in Table 1. Calculate the distance between point A m and the connecting line A1A2 of the main material endpoints according to formulas (1)-(3), and obtain the deformation of the main material of leg A as 0.1015 m; calculate the main material camber as 4.16‰ according to formula (7).

[0101] Table 1 Coordinates and camber of the measuring points of the main material of leg A

[0102]

[0103] Using the method proposed in the present invention, the measured main material camber of leg A is 4.55‰, with a difference of 0.39‰ from the measurement result of the total station; compare the main material cambers of other main materials in the same way, and the measurement errors are all less than 0.5‰, and the measurement accuracy meets the application requirements of actual projects. This error is, on the one hand, the measurement error of the total station and the 3D laser scanner, and on the other hand, the total station can only measure the bolts adjacent to the main material ridge line and cannot directly take points on the main material ridge line, resulting in coordinate errors of the measuring points. The method proposed in the present invention can effectively solve the problem that it is difficult for the total station to directly measure the main material ridge line and improve the measurement accuracy.

[0104] The method proposed by the present invention does not require leveling of the support. The setup time is less than 10 minutes, the single-station measurement time is 2 minutes, and the measurement time for three stations (including setup time) is only 36 minutes. When using a total station for measurement, it is necessary to level the support, which generally takes 30 minutes. Each main material needs to be measured point by point, taking 60 minutes, and four groups of main materials require 360 minutes. The measurement method proposed by the present invention can reduce the number of setup times, the leveling of the support, and the time for point-by-point measurement, reducing the outdoor operation time to 10%, and greatly improving the measurement efficiency.

[0105] In summary, compared with the prior art, the measurement method proposed by the present invention can effectively solve the technical problem of difficult measurement of the bending degree of the main materials of the pole tower. It has the advantages of high measurement accuracy and small workload, and helps to solve the detection of the structural deformation of the pole tower caused by harsh working conditions such as geological disasters, ice galloping, and extreme strong winds, and supports the maintenance personnel to timely discover the structural damage of the pole tower.

[0106] Another embodiment of the present invention provides a system for detecting the deformation amount and bending degree of the main materials of a pole tower based on three-dimensional laser point cloud, including: a computer-readable storage medium and a processor;

[0107] The computer-readable storage medium is used to store executable instructions;

[0108] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the method for detecting the deformation amount and bending degree of the main materials of the pole tower based on three-dimensional laser point cloud.

[0109] Another embodiment of the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the method for detecting the deformation amount and bending degree of the main materials of the pole tower based on three-dimensional laser point cloud described in the first aspect.

[0110] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, such that the instructions executed by the processors of the computer or other programmable data processing devices produce means for implementing the functions specified in one or more flows and / or one or more blocks in the flow Figure 1 one or more flows and / or one or more blocks Figure 1 of the functions specified in the block.

[0112] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one or more flows and / or one or more blocks in the flow Figure 1 one or more flows and / or one or more blocks Figure 1 of the functions specified in the block.

[0113] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows and / or one or more blocks in the flow Figure 1 one or more flows and / or one or more blocks Figure 1 of the functions specified in the block.

[0114] 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 above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A method for detecting deformation of main material of transmission tower based on three-dimensional laser point cloud, characterized in that: The following steps are involved: Step 1: Scan the transmission tower at multiple angles using a ground-based three-dimensional laser scanner to obtain a tower point cloud, and perform noise reduction processing on the tower point cloud; Step 2: Use the PCA algorithm to orient and rotate the tower point cloud after noise reduction; Step 3: horizontally slice and project the oriented and rotated tower point cloud along the tower height direction, and extract the point cloud data of the tower body quadrangular platform according to the aspect ratio, area ratio and number of slice points of each layer of slices; Step 4: Based on the point cloud data of the tetrahedron, the coordinates of the four vertices of each horizontal slice are calculated respectively; Step 5: Calculate the vertical distance between the vertices of each slice and the line connecting the endpoints of the main material according to the coordinates of the four vertices; Step 6: By analyzing the slope change of the distance between the vertices of each layer of slices, determine whether there is a slope change point, and remove the corresponding tetrahedral slice above the slope change point; Step 7: Based on the vertex coordinates of the remaining tetrahedral slices, calculate the deformation, curvature and position information of the main material.

2. The method according to claim 1, characterized in that The step 3 comprises: Step 3.1, calculation of tower point cloud slice parameters: use a set of planes with a thickness of δ to intersect the point cloud, slice the point cloud from bottom to top, and obtain the point cloud slice S i , and then project each layer of point cloud slices onto the horizontal plane to obtain the projection slice S i ', calculate the side length l of each layer of point cloud slices respectively ix ,l iy , area i 、Number of points n i , and then calculate the area of ​​the circumscribed rectangle and aspect ratio Step 3.2, extraction of the tower body tetrahedral structure: According to the tower structure judgment criteria, extract the tower body tetrahedral structure, denoted as S i , i = 1, 2, ... m, the judgment criteria are: ① The area of ​​the circumscribed rectangle of the slice is continuous, there is no mutation layer, and the slice area ratio satisfies: Where s i Project S for the i-th slice i 'The area of ​​the circumscribed rectangle; ②The aspect ratio of the circumscribed rectangle of the section satisfies: Where l ix ,l iy Project S for the i-th slice i 'The length and width of the circumscribed rectangle; ③The number of slice points n i Should be greater than 1000.

3. The method according to claim 2, characterized in that The step 4 comprises: Step 4.1, extract the vertices A and C of the tetrahedral slice: for each layer of the tetrahedral slice point cloud S i , i=1,2,…m, perform the following operation, with S i For example, S i The coordinates of the midpoint cloud are (x i ,y i ,z i ), i=1,2,…n, calculate x respectively i +y i , i = 1, 2, ... n, extract min (x i +y i ) and max(x i +y i ), extract k minimum and maximum values ​​in turn, take the average of the coordinates of the k points, record the minimum value as point A, and its coordinates are The maximum value is recorded as point C, and its coordinates are Step 4.2, extract the vertices B and D of the tetrahedral slice: for each layer of the tetrahedral slice point cloud S i , i=1,2,…m, perform the following operation, with S i For example, S i Rotate 90° counterclockwise and repeat the above steps to get point B and point D, whose coordinates are Step 4.3, get the vertex coordinates of the tetrahedron: merge the vertices of the m layers of point cloud slices to get the vertex coordinates of the tetrahedron slice, denoted as A i ,B i ,C i ,D i ,i=1,2,…m.

4. The method according to claim 3, characterized in that The step 5 comprises: Step 5.1, calculate the distance between the vertex of the main material of group A and the end point of the main material: the vertex of the main material of group A is A i ,i=1,2,…m, its coordinates are (x A.i ,y A. ,z A.i ),i=1,2,…m, where the endpoint coordinates are A1(x A.1 ,y A.1 ,z A.1 ), A m (x A.m ,y A.m ,z A.m ). i (x A.i ,y A.i ,z A.i ) and the endpoints as an example, calculate A i Distance A1, A m The distance of the connection line is as follows: Calculate the length of each side A1A m 、A1A i , A i A m , the half perimeter is: The area of ​​the triangle s is: A i Distance A1, A m The distance between the lines is: Step 5.2: According to the above steps, calculate the distance between the main material vertex of group B, C, and D and the main material endpoint, recorded as d A.i ,d B.i ,d C.i ,d D.i ,i=1,2,…m.

5. The method according to claim 4, characterized in that The step 6 comprises: Step 6.1: The distance d between the four main materials A, B, C, and D A.i ,d B.i ,d C.i ,d D.i , i=1,2,…m for difference: Step 6.2, set the points whose distance difference of the four main materials is less than 0 to 1, and the points whose distance difference is greater than 0 to 0: Step 6.3, sum the above four sets of values: Step 6.4, when the offset of the three main materials decreases continuously, that is When , the kth layer is determined to be a slope change point, recorded as m'=k, and the point cloud slice above the slope change point is removed.

6. The method according to claim 5, characterized in that The step 7 comprises: According to step 5, calculate the main material vertex A of groups A, B, C, and D in turn. i ,B i ,C i ,D i ,i=1,2,…m' from the main material endpoint A i ,B i ,C i ,D i ,i=1,m'The distance between the lines is d' A.i ,d' B.i ,d' C.i ,d' D.i ,i=1,2,…m', where the height of the slice where the main material deformation is located (z A.i ,z B.i ,z C.i ,z D.i ) is the deformation position; The curvature of the main material is calculated according to the following formula: In the formula, the slice layer where the maximum value of the main material deformation is located is (A.max.i, B.max.i, C.max.i, D.max.i), and the height of the slice layer is (z A.max.i ,z B.max.i ,z C.max.i ,z D.max.i ) is the position of maximum deformation rate.

7. A tower main material deformation and curvature detection system based on three-dimensional laser point cloud, comprising: A computer readable storage medium and a processor; The computer-readable storage medium is used to store executable instructions; The processor is used to read the executable instructions stored in the computer-readable storage medium, and execute the method for detecting the deformation and curvature of the main material of the tower based on three-dimensional laser point cloud according to any one of claims 1 to 6.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for detecting deformation and curvature of a tower main material based on three-dimensional laser point cloud as described in any one of claims 1 to 6.

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