Unmanned aerial vehicle continuous tower foundation three-dimensional inspection path planning method based on laser point cloud

Abstract

The application relates to a kind of unmanned plane continuous tower base three-dimensional inspection path planning methods based on laser point cloud, which includes the following steps: step 1: obtaining the laser point cloud data of power transmission line and extracting the plane position information and elevation information of measured points as to-be-processed information;Step 2: the to-be-processed information is down-sampled to obtain to-be-filtered information;Step 3: the elevation threshold is used to filter the to-be-filtered information, and the plane position information and elevation information of the measured points with the elevation information higher than the elevation threshold are retained as to-be-fitted information;Step 4: segmented fitting is carried out using to-be-fitted information, and the multi-segment linear equation of power transmission line based on geodetic coordinates is obtained;Step 5: the lightning conductor coordinates are extracted using the multi-segment linear equation, and the continuous track point coordinates are obtained;Step 6: obtaining the unmanned plane inspection track point position information;Step 7: obtaining the three-dimensional inspection path of the unmanned plane.The application can quickly plan the unmanned plane inspection path, and the effect is ideal.

Description

Technical Field

[0001] This invention relates to the field of power line inspection technology, specifically to a method for planning a continuous three-dimensional inspection path for tower bases using unmanned aerial vehicles (UAVs) based on laser point clouds. Background Technology

[0002] Drones are a core component of intelligent alternatives for power line inspection. Currently, the autonomous drone inspection mode involves manual operation to scan the entire power line corridor and towers, collect laser point cloud data, and create 3D models to plan the drone's flight path, thus achieving autonomous inspection. Flight path planning relies on extracting the coordinates of conductors and towers from the laser point cloud data of the transmission lines. Lightning conductors and transmission lines are located in the same position in the two-dimensional plane, differing only in elevation. Conductors of different voltage levels have specific vertical distance requirements. Extracting the coordinates of the lightning conductors facilitates drone inspection of defects and allows for adjusting the drone's flight path elevation to inspect the transmission lines beneath them. Existing technologies employ various clustering, search, and fitting algorithms to extract and reconstruct transmission lines from point cloud data. However, these studies typically involve only a few million point cloud data points. When faced with much larger datasets, such as over 300 million, existing algorithms require significant time to execute and cannot quickly obtain conductor coordinates, thus impacting the efficiency of drone inspection path planning. Summary of the Invention

[0003] The purpose of this invention is to provide a method for quickly extracting the coordinates of lightning protection wires in power transmission lines from a large amount of point cloud data, thereby efficiently planning the inspection path of unmanned aerial vehicles (UAVs).

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for planning a three-dimensional inspection path for a continuous power transmission line tower base using a UAV based on laser point cloud data is provided. This method extracts the coordinates of lightning protection wires from laser point cloud data of the transmission line and plans the three-dimensional inspection path for the UAV. The method includes the following steps:

[0006] Step 1: Obtain the laser point cloud data of the transmission line and extract the planar position information and elevation information of each measured point as the information to be processed. Divide the information to be processed into multiple groups according to the multiple conductor segments obtained by dividing the transmission conductor in the transmission line.

[0007] Step 2: Perform downsampling processing on each group of information to be processed to obtain multiple groups of information to be filtered.

[0008] Step 3: Perform elevation filtering on each group of information to be filtered using a preset elevation threshold, and retain the planar position information and elevation information of the measured point whose elevation information is higher than the elevation threshold as the information to be fitted;

[0009] Step 4: Use the information to be fitted to perform piecewise fitting to obtain the piecewise linear equation of the transmission line in the xoy plane based on geodetic coordinates;

[0010] Step 5: Perform the following steps for each line segment of the piecewise linear equation:

[0011] Step 5-1: Obtain the coordinates of each measured point on the transmission line corresponding to the straight line segment in the xoy plane as the geodetic coordinates in the original coordinate system;

[0012] Step 5-2: Rotate the straight line segment in the xoy plane so that it is parallel to the x-axis in the xoy plane. At this time, the coordinates of each measured point on the transmission line corresponding to the straight line segment in the xoy plane are converted as the coordinates in the new coordinate system.

[0013] Step 5-3: Set the unit length by dividing the transmission line into equal segments along the x-axis, with each segment of the transmission line having a length equal to the unit length;

[0014] Step 5-4: Set matrices XB, YB, and ZB. The lengths of matrices XB, YB, and ZB are all the number of segments into which the transmission line is divided equally along the x-axis. The elements in matrix XB correspond to the x-coordinates of the measured points on each segment of the transmission line, the elements in matrix YB correspond to the y-coordinates of the measured points on each segment of the transmission line, and the elements in matrix ZB correspond to the z-coordinates of the measured points on each segment of the transmission line. The initial values ​​of matrices XB, YB, and ZB are all 0.

[0015] Step 5-5: Traverse each segment of the transmission line. For any segment of the transmission line, if the measured point on the transmission line satisfies the condition that the x-coordinate is within the corresponding segment interval and the z-coordinate is greater than the value of the corresponding element in the matrix ZB, then update the corresponding elements in the matrix XB, the matrix YB, and the matrix ZB using the coordinates of the current measured point in the new coordinate system.

[0016] Steps 5-6: Remove zero values ​​from matrices XB, YB, and ZB;

[0017] Steps 5-7: Extract the point cloud data of the lightning protection line in the new coordinate system based on the matrix XB, the matrix YB, and the matrix ZB;

[0018] Steps 5-8: Based on the point cloud data of the lightning protection line in the new coordinate system, offset each point cloud data point by a meters along the positive y-axis and d meters along the negative z-axis to obtain the coordinates of the UAV's tracking guide track point in the new coordinate system;

[0019] Steps 5-9: Based on the point cloud data of the lightning protection line in the new coordinate system, find the point cloud data that is b meters away from the center of each tower along the transmission line and offset it c meters in the positive z-axis direction to obtain the coordinates of the UAV's connection point between the tower and the transmission line in the new coordinate system.

[0020] Steps 5-10: Based on the coordinates of the UAV's tracking traverse track points in the new coordinate system and the coordinates of the UAV's connection track points between the tower and the traverse in the new coordinate system, interpolation is performed at the discontinuities in the track points to obtain the coordinates of the continuous track points in the new coordinate system.

[0021] Step 5-11: Convert the coordinates of the continuous track points in the new coordinate system to the geodetic coordinates of the continuous track points in the original coordinate system;

[0022] Step 6: Convert the x and y coordinates of the continuous track points in the original coordinate system to the latitude and longitude coordinates of the continuous track points in the original coordinate system, thereby obtaining the location information of the UAV inspection track points;

[0023] Step 7: Obtain the three-dimensional inspection path of the UAV based on the location information of the UAV inspection flight track points.

[0024] In step 1, the planar position information and elevation information of the measured point are extracted using the laspy library of the Python language.

[0025] In step 1, the power transmission line is divided into multiple conductor segments according to the tower location and the number of laser point cloud data, such that the number of laser point cloud data corresponding to each conductor segment is between 40 million and 80 million.

[0026] In step 2, functions from the Open3D library are used to downsample the data to be processed after format conversion.

[0027] In step 2, the information to be processed is downsampled using uniform downsampling, voxel downsampling, or curvature downsampling.

[0028] In step 3, the elevation threshold corresponding to each of the conductor segments is the sum of the average elevation of the conductor segment and a preset value.

[0029] For the transmission line located in mountainous or rugged areas, in step 3, the information to be filtered is sorted based on the x-axis coordinate or y-axis coordinate and divided into several small areas, and the elevation filtering process is performed in each of the small areas.

[0030] In step 4, when performing piecewise fitting, if a segment of the transmission line cannot form a function about the y-axis in the x-axis direction, then the x-axis and y-axis directions are transformed for fitting, and the obtained function is transformed by inverse function to obtain the corresponding linear equation; if a segment of the transmission line cannot form a function in either the x-axis or y-axis direction, then it is re-segmented and piecewise fitting is performed again.

[0031] In step 5, the segmentation points of the piecewise linear equation are the tower locations.

[0032] In step 5-1, the density of the measured point on the transmission line is obtained using the density function in the seaborn library, and then the position of the tower is determined using the density of the measured point on the transmission line.

[0033] In steps 5-8, the value of a is 2, and the value of d is determined by the voltage level of the transmission line, which can be 2, 3.5, 6, or 10.

[0034] In steps 5-9, the value of b is 10, and the value of c is 2.

[0035] In steps 5-10, linear interpolation is performed at points where the track points are discontinuous.

[0036] In step 6, the x and y coordinates of the continuous track points in the original coordinate system are converted into latitude and longitude coordinates of the continuous track points in the original coordinate system using a four-parameter planar model.

[0037] In step 7, the location information of the drone's inspection flight path is input into the drone terminal for autonomous flight.

[0038] In step 5-2, based on the slope tanα of the line segment, the rotation angle of the line segment is made equal to α. Then, using... Calculate the coordinates of each measured point on the transmission line corresponding to the straight line segment in the new coordinate system, where, The value of is -α, and X1 and Y1 are the x and y coordinates of each measured point on the transmission line corresponding to the straight line segment in the original coordinate system. These are the x and y coordinates of each measured point on the transmission line corresponding to the straight line segment in the new coordinate system.

[0039] In steps 5-11, using Calculate the geodetic coordinates of the continuous flight path points in the original coordinate system, where, The value of α is given by X2, Y2, and Z2, which are the x, y, and z coordinates of the continuous track points in the original coordinate system. These are the x, y, and z coordinates of the continuous track points in the new coordinate system.

[0040] In step 6, using Calculate the latitude and longitude coordinates of the continuous track points in the original coordinate system, where X2 and Y2 are the x and y coordinates of the continuous track points in the original coordinate system, X3 and Y3 are the latitude and longitude coordinates of the continuous track points in the original coordinate system, ΔX0 and ΔY0 are translation parameters, ε is the rotation parameter, and m is the scale parameter.

[0041] The translation parameters, rotation parameters, and scale parameters are calculated using two pairs of control points, and the coordinates of each pair of control points in the geodetic coordinate system and the coordinates in the latitude and longitude coordinate system are known.

[0042] Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art: the present invention can quickly locate the position of the lightning protection wire in the power transmission line, thereby quickly realizing the planning of the inspection path of the UAV, with ideal results. Attached Figure Description

[0043] Appendix Figure 1 This is a flowchart of the UAV continuous tower base three-dimensional inspection path planning method based on laser point cloud according to the present invention.

[0044] Appendix Figure 2 This is a schematic diagram of uniform downsampling.

[0045] Appendix Figure 3 This is a schematic diagram of voxel downsampling.

[0046] Appendix Figure 4 This is a schematic diagram of curvature downsampling.

[0047] Appendix Figure 5 This is a schematic diagram of elevation filtering.

[0048] Appendix Figure 6 This is a 3D diagram of a poleless power transmission line.

[0049] Appendix Figure 7 This is a two-dimensional projection of a poleless transmission line in the xoy plane.

[0050] Appendix Figure 8 This is a two-dimensional projection of a poleless transmission line in the xoy plane after rotation.

[0051] Appendix Figure 9 This is a two-dimensional projection of a poleless transmission line in the xoz plane after rotation.

[0052] Appendix Figure 10 This is a schematic diagram of a power transmission line containing towers.

[0053] Appendix Figure 11 This is a schematic diagram illustrating the use of the density function to locate tower positions. Detailed Implementation

[0054] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings.

[0055] Example 1: A power transmission line consists of several towers and transmission lines erected on the towers. Typically, two sets of transmission lines are erected on either side of each tower, and each set of transmission lines includes a lightning protection wire at the top and several transmission conductors below the lightning protection wire. The vertical spacing of the transmission conductors varies depending on the voltage level of the transmission line. Generally, the top transmission conductor is located approximately 2.5 meters below the lightning protection wire. The vertical spacing of 35kV transmission conductors is approximately 2 meters, 110kV transmission conductors are approximately 3.5 meters, 220kV transmission conductors are approximately 6 meters, and 500kV transmission conductors are approximately 10 meters.

[0056] As attached Figure 1 As shown, a method for planning a three-dimensional inspection path for a UAV on a continuous tower base based on laser point cloud data, used to extract the coordinates of lightning protection wires from laser point cloud data of power transmission lines and plan the three-dimensional inspection path of a UAV, includes the following steps:

[0057] Step 1: Obtain laser point cloud data of the transmission line and extract the planar position information and elevation information of each measured point as the information to be processed. Divide the information to be processed into multiple groups based on the multiple conductor segments obtained by dividing the transmission conductor in the transmission line.

[0058] The laser point cloud data is acquired by radar. When acquiring laser point cloud data for power transmission lines, a drone equipped with radar flies directly above the transmission lines and towers, employing Time-of-Flight (TOF) technology to ensure that the radar measurement accuracy remains consistent with distance, maintaining precise and stable accuracy even for distant objects. Since the drone's flight altitude is known, the elevation of the measured point can be calculated, and subsequent algorithms can then determine the position of the power transmission line.

[0059] The laser point cloud data is in LASIK format. Point cloud information includes: the planar position and elevation of the measured point, RGB (red, green, blue) color information, and reflection intensity. The planar position and elevation information of the measured point are extracted using the laspy library in Python for further study. Elevation refers to altitude, measured in meters.

[0060] The geodetic coordinate system is a right-handed 3D coordinate system centered on the Earth, fixed on the planet. It consists of three orthogonal axes: the x-axis and y-axis lie in the equatorial plane, and the z-axis is parallel to the mean Earth's rotation axis and points towards the North Pole. Using Python programming, all three-dimensional points in the laser point cloud data are projected onto a two-dimensional plane, resulting in a strip-shaped route map that aligns with the route distribution obtained through the latitude and longitude coordinates of the towers.

[0061] Because laser point cloud data is massive—for example, the data size of a single power transmission line is approximately 10GB, with over 300 million measured points—a typical computer with 8GB of memory cannot process over 300 million data points at once. Therefore, based on the tower locations and the amount of laser point cloud data, the power transmission line is divided into multiple conductor segments, resulting in each segment containing 40 to 80 million laser point cloud data points. For example, the aforementioned power transmission line could be divided into 5 conductor segments, each with 40 to 80 million points, before subsequent downsampling processing.

[0062] Step 2: Downsample each group of information to be processed to obtain multiple groups of information to be filtered.

[0063] First, the LAS format data needs to be converted to PCD format. Then, functions from the Open3D library are used to downsample the converted data. Since the transmission line is divided into multiple segments, downsampling is performed on the information corresponding to each segment separately.

[0064] Downsampling methods generally include uniform downsampling, voxel downsampling, and curvature downsampling. Therefore, uniform downsampling, voxel downsampling, or curvature downsampling is used to downsampling the information to be processed. The differences between the three are as follows:

[0065] (1) As attached Figure 2 As shown, there are several methods for uniform downsampling. Among them, sampling at the farthest point is relatively simple. First, a seed point needs to be selected, and an inner point set needs to be set. Each time, the point farthest from the inner point is found from the set of non-inner points in the point cloud. This method results in a uniform distribution of the sampled point cloud, but the algorithm has high complexity and low efficiency.

[0066] (2) As attached Figure 3As shown, voxel downsampling involves voxelizing the 3D space and then sampling a point within each voxel. Typically, the center point or the point closest to the center can be used as the sampling point. This method has very high sampling efficiency, and the sampling points are relatively evenly distributed. The spacing between points can be controlled by the voxel size, but the number of sampling points cannot be precisely controlled.

[0067] (3) As attached Figure 4 As shown, curvature downsampling involves sampling more points where the curvature of the point cloud is greater. First, the neighborhood of each point is calculated. Then, the angle between the point and the normal to its neighbors is calculated; the greater the curvature, the larger this angle value. Next, an angle threshold is set (30° in this paper). Points with neighborhood angle values ​​greater than this threshold are considered to have obvious features, while the rest are considered indistinct regions. Finally, the obvious and indistinct regions are sampled uniformly, with sample numbers of S*(1-U) and S*U, respectively, where S is the target sample number and U represents the sampling uniformity. This method results in a locally uniform distribution of sampled points, and the division of geometric feature regions makes the sampling results more robust to noise.

[0068] The advantages and disadvantages of the three are as follows:

[0069] (1) In terms of time, uniform downsampling and voxel downsampling take the shortest time, while curvature downsampling takes much longer. Taking a line containing about 87 million point clouds as an example, voxel downsampling takes about 8 seconds, uniform downsampling takes about 5 seconds, and curvature downsampling takes about 2.2 hours. This is because curvature downsampling requires first extracting points, calculating the angle between their normal vectors and the neighborhood fitting plane, then classifying the angle values, and finally sampling according to the classification results based on weights.

[0070] (2) In terms of results, voxel downsampling yields the fewest points, while the other two depend on the parameters. Taking a line containing approximately 87 million point clouds as an example, voxel downsampling with a voxel size of 5 yields about 50,000 points; uniform downsampling with one point sampled every 100 points yields about 870,000 points; curvature downsampling with a neighborhood of 50 points and an angle threshold of 30°, sampling one point every 100 points in areas with obvious features and one point every 200 points in areas with indistinct features, finally yields about 600,000 points.

[0071] It is evident that uniform downsampling and curvature downsampling yield a larger number of points, preserving tower, conductor, and ground features more completely. Curvature downsampling, however, is more advantageous in reflecting local features. Voxel downsampling yields sparser points, almost failing to preserve tower point clouds and significantly reducing ground point clouds. However, the sparse conductor point cloud still effectively reflects the planar distribution characteristics of the conductor. Considering both time cost and sampling effect, voxel downsampling is the optimal choice.

[0072] Step 3: Perform elevation filtering on each group of information to be filtered using a preset elevation threshold, and retain the planar position information and elevation information of the measured points whose elevation information is higher than the elevation threshold as the information to be fitted.

[0073] The elevation threshold for each conductor segment is the sum of the average elevation of the segment and a preset value. For example, according to the overhead transmission line operation regulations, the shortest distance between a 220kV transmission conductor and the ground is 7.5m, and the top of the tower is generally 30m above the ground. Considering that there are few buildings with similar elevations near a certain section of the transmission line and that the transmission line is located in a plain area, the elevation threshold is set to the average elevation of a conductor segment plus 20m. (See attached image) Figure 5 As shown, elevation filtering can filter out all ground points, retaining only the lightning protection wire and two or three conductors, without affecting the construction of the plane equation. A very few discrete points may be flying objects, such as birds.

[0074] The above elevation filtering scheme is applicable to plains. For transmission lines located in mountainous or rugged areas, in step 3, the information to be filtered is sorted based on the x-axis coordinate or y-axis coordinate, divided into several small areas, and elevation filtering is performed in each small area.

[0075] Step 4: Use the information to be fitted to perform piecewise fitting to obtain a multi-piece linear equation of the transmission line based on geodetic coordinates. This multi-piece linear equation is the linear equation of the transmission line on the xoy plane.

[0076] After elevation filtering, only the point cloud of the transmission line and some towers remain. Projected onto a two-dimensional plane, these are segmented straight lines. Further piecewise linear fitting yields the linear equation of the transmission line in the geodetic coordinate system. The piecewise linear equation is as follows:

[0077]

[0078] The premise of multi-segment fitting is that y is a function of x. If a segment of the transmission line cannot form a function of x in the y-axis direction, then the x-axis and y-axis directions are transformed for fitting, and the resulting function is transformed by inverse function to obtain the corresponding linear equation of uniform variables; if a segment of the transmission line cannot form a function in either the x-axis or y-axis direction, then it is re-segmented and then piecewise fitting is performed.

[0079] Step 5: The segmentation points of the piecewise linear equation are the tower locations. Perform the following steps for each line segment of the piecewise linear equation to extract the coordinates of the lightning protection wire:

[0080] Step 5-1: Obtain the coordinates of each measured point on the transmission line corresponding to the straight line segment in the xoy plane as the geodetic coordinates in the original coordinate system. The coordinates of the measured points in the xoy plane are obtained from the planar position information of the measured points.

[0081] Step 5-2: Rotate the straight line segment in the xoy plane until it is parallel to the x-axis in the xoy plane. Then, transform the coordinates of each measured point on the transmission line corresponding to the straight line segment in the xoy plane as the coordinates in the new coordinate system.

[0082] Specifically, for each line segment, its slope tanα can be calculated. The following functions can be used to obtain the coordinates of the segmentation points and the slope of each line segment in a piecewise linear equation:

[0083] breaks = myPWLF.fit(value), where value represents the number of segments.

[0084] slopes = myPWLF.calc_slopes()

[0085] If there are no towers in the straight section, the three-dimensional diagram of the transmission line and its two-dimensional projection in the xoy plane are shown in the attached figures. Figure 6 , 7 As shown. Based on the slope tanα of the line segment, rotating the line segment by an angle equal to α can make the conductor parallel to the x-axis, as shown in the attached figure. Figure 8 As shown, then using Calculate the coordinates of each measured point on the transmission line corresponding to the straight line segment in the new coordinate system. The value of is -α, because the rotation matrix takes counterclockwise as the positive direction. α, mentioned above, is the angle between the conductor and the x-axis. X1 and Y1 are the x and y coordinates of the measured points on the transmission line corresponding to the straight line segment in the original coordinate system. These are the x and y coordinates of each measured point on the transmission line corresponding to the straight segment in the new coordinate system. After planar rotation, the elevation (z coordinate) of each point cloud remains unchanged. The projection of the transmission line onto the xoz plane after planar rotation is shown in the attached figure. Figure 9 As shown, the distance between the lightning protection wire and the conductors below it is obvious, while the corresponding conductors of the left and right circuits almost overlap. Since the lightning protection wire is located at the top, its coordinates can be extracted.

[0086] Step 5-3: Set the unit length by dividing the transmission line into equal segments along the x-axis, with each segment equal to the unit length. Too small a unit length will result in more discrete point clouds of the lower conductors, while too large a unit length will waste a significant amount of lightning protection corona discharge; therefore, a reasonable selection is necessary.

[0087] Step 5-4: Set matrices XB, YB, and ZB. The lengths of matrices XB, YB, and ZB are the number of segments into which the transmission line is divided equally along the x-axis. The elements in matrix XB correspond to the x-coordinates of the measured points on each transmission line segment, the elements in matrix YB correspond to the y-coordinates of the measured points on each transmission line segment, and the elements in matrix ZB correspond to the z-coordinates of the measured points on each transmission line segment. The initial values ​​of matrices XB, YB, and ZB are all 0.

[0088] Step 5-5: Traverse each segment of the transmission line, that is, traverse each x-interval after the transmission line is segmented. For any segment of the transmission line, if the measured point on the transmission line satisfies the condition that its x-coordinate is within the corresponding segment interval and its z-coordinate is greater than the value of the corresponding element in matrix ZB, then update the corresponding elements in matrices XB, YB, and ZB using the coordinates of the current measured point in the new coordinate system. The z-coordinate of the measured point is obtained from its elevation information. Thus, the final matrices XB, YB, and ZB contain information about the lightning protection wire.

[0089] Steps 5-6: Remove zero values ​​from matrices XB, YB, and ZB, because there may be no point cloud in a very small number of x intervals.

[0090] Steps 5-7: Extract the point cloud data of the lightning protection line in the new coordinate system based on matrices XB, YB, and ZB.

[0091] Steps 5-8: Based on the point cloud data of the lightning protection line in the new coordinate system, offset each point cloud data by a meters along the positive y-axis and d meters along the negative z-axis. This means increasing each element in matrix YB by a, decreasing each element in matrix ZB by d, and keeping each element in matrix XB unchanged, thereby obtaining the coordinates of the UAV's tracking guide track points in the new coordinate system.

[0092] In this step, the value of a is 2, and the value of d is determined by the voltage level of the transmission line. That is, for a 35kV transmission line, the value of d is 2; for a 110kV transmission line, the value of d is 3.5; for a 220kV transmission line, the value of d is 6; and for a 500kV transmission line, the value of d is 10.

[0093] Steps 5-9: Based on the point cloud data of the lightning protection line in the new coordinate system, find the point cloud data b meters away from the center of each tower along the transmission line and offset it c meters in the positive z-axis direction to obtain the coordinates of the UAV's connection point between the tower and the transmission line in the new coordinate system.

[0094] In this step, b is set to 10 and c is set to 2. That is, at a distance of 10 meters from the center of each tower along the direction of the transmission line, each element in matrix ZB is increased by 2, while each element in matrix XB and matrix YB remains unchanged, thus obtaining the tower connection track point where the tower connects to the transmission line.

[0095] The coordinates of the tracking wires and the coordinates of the connection points between the towers and the wires together constitute the track points for UAV inspection.

[0096] Steps 5-10: Based on the coordinates of the UAV's tracking traverse track points in the new coordinate system and the coordinates of the UAV's connection track points between the tower and the traverse in the new coordinate system, linear interpolation is performed at the discontinuities in the track points to obtain the coordinates of the continuous track points in the new coordinate system.

[0097] Step 5-11: Convert the coordinates of the continuous track points in the new coordinate system to the geodetic coordinates of the continuous track points in the original coordinate system;

[0098] In this step, using Calculate the geodetic coordinates of the continuous flight path points in the original coordinate system, where, The value of α is given by X2, Y2, and Z2, which are the x, y, and z coordinates of the continuous track points in the original coordinate system. These are the x, y, and z coordinates of the continuous track points in the new coordinate system.

[0099] Step 6: Using a four-parameter planar model, the x and y coordinates of the continuous track points in the original coordinate system are converted into latitude and longitude coordinates of the continuous track points in the original coordinate system, while the z coordinate in the original coordinate system remains unchanged, thereby obtaining the location information of the UAV inspection track points.

[0100] In this step, using Calculate the latitude and longitude coordinates of the continuous track points in the original coordinate system, where X2 and Y2 are the x and y coordinates of the continuous track points in the original geodetic coordinate system, X3 and Y3 are the latitude and longitude coordinates of the continuous track points in the original coordinate system, ΔX0 and ΔY0 are translation parameters, ε is the rotation parameter, and m is the scale parameter. The translation, rotation, and scale parameters are calculated using two pairs of control points (points whose geodetic coordinates and latitude / longitude coordinates are both known). The coordinates of each pair of control points in the geodetic coordinate system and the latitude / longitude coordinate system are known.

[0101] Step 7: Based on the location information of the UAV inspection track points, the three-dimensional inspection path of the UAV is obtained. Therefore, the location information of the UAV inspection track points (including latitude and longitude coordinates and elevation) can be input into the RTK centimeter-level positioning UAV terminal for autonomous flight to realize the inspection of power transmission lines.

[0102] In step 5-1 above, if the transmission line corresponding to the straight segment contains towers, as shown in the attached... Figure 10 As shown, the coordinates of each measured point on the transmission line in the xoy plane are extracted using the tower as the dividing point. The location of the tower can be determined by the density of the measured points on the transmission line. For example, the density function in the seaborn library can be used to obtain the density of the measured points on the transmission line, and the x-positions with significantly higher density can be found through the density function, which are the tower locations (e.g., ...). Figure 11 It is obvious that the locations of 7 towers can be found. Using these as the dividing point, the conductor point cloud between the towers is extracted, and then the coordinates of the lightning protection wire are extracted.

[0103] The above scheme, based on laser point cloud data of transmission lines, utilizes downsampling, elevation filtering, and multi-piece linear fitting to quickly determine conductor positions, thereby extracting the specific locations of lightning protection wires and enabling rapid inspection path planning. Among conductor extraction algorithms, voxel downsampling offers advantages in both time cost and sampling quality compared to uniform downsampling and curvature downsampling. Multi-piece linear fitting performs well, with an average fitting time of 10 seconds per line segment. For line distributions with non-functional properties, x and y coordinates can be converted or piecewise fitting can be performed. This scheme is well-suited for transmission lines in plain areas, and some fitting error may occur if multiple transmission lines are present during laser point cloud data scanning.

[0104] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for planning a three-dimensional inspection path for a UAV continuous tower base based on laser point cloud data, used to extract the coordinates of lightning protection wires from laser point cloud data of power transmission lines and plan the three-dimensional inspection path of the UAV, characterized in that: The method for planning the continuous three-dimensional inspection path of tower bases using UAVs based on laser point clouds includes the following steps: Step 1: Obtain the laser point cloud data of the transmission line and extract the planar position information and elevation information of each measured point as the information to be processed. Divide the information to be processed into multiple groups according to the multiple conductor segments obtained by dividing the transmission conductor in the transmission line. Step 2: Perform downsampling processing on each group of information to be processed to obtain multiple groups of information to be filtered. Step 3: Perform elevation filtering on each group of information to be filtered using a preset elevation threshold, and retain the planar position information and elevation information of the measured point whose elevation information is higher than the elevation threshold as the information to be fitted; Step 4: Use the information to be fitted to perform piecewise fitting to obtain the data based on geodetic coordinates. x -o- y The piecewise linear equations of the transmission lines in the plane; Step 5: Perform the following steps for each line segment of the piecewise linear equation: Step 5-1: Obtain the measured points on the transmission line corresponding to the straight segment at the specified locations. x -o- y The coordinates in the plane are used as geodetic coordinates in the original coordinate system; Step 5-2: In the x -o- y Rotate the line segment in the plane so that it is aligned with the plane. x -o- y in plane x When the axes are parallel, the transformation yields the measured points on the transmission line corresponding to the straight line segment. x -o- y The coordinates in the plane are used as coordinates in the new coordinate system; Step 5-3: Set the unit length and extend the transmission line along... x The conductor is divided into equal segments along the axial direction, and the length of each segment of the conductor is equal to the unit length. Step 5-4: Set matrices XB, YB, and ZB, wherein the lengths of matrices XB, YB, and ZB are all equal to the lengths of the transmission conductor along... x The number of segments in the axial direction, and the elements in the matrix XB correspond to the measured points on each segment of the transmission line. x Coordinates, the elements in the matrix YB correspond to the measured points on each segment of the transmission line. y Coordinates, the elements in the matrix ZB correspond to the measured points on each segment of the transmission line. z The coordinates are such that the initial values ​​of the matrices XB, YB, and ZB are all 0. Step 5-5: Traverse each segment of the transmission line. For any segment of the transmission line, if the measured point on the transmission line satisfies... x The coordinates are within the corresponding segment interval and z If the coordinates are greater than the value of the corresponding element in matrix ZB, then the corresponding elements in matrix XB, matrix YB, and matrix ZB are updated using the coordinates of the current measured point in the new coordinate system. Steps 5-6: Remove zero values ​​from matrices XB, YB, and ZB; Steps 5-7: Extract the point cloud data of the lightning protection line in the new coordinate system based on the matrix XB, the matrix YB, and the matrix ZB; Steps 5-8: Based on the point cloud data of the lightning protection line in the new coordinate system, align each point cloud data point along... y Offset in the positive direction of the axis a Rice, along z Negative axis offset d The coordinates of the UAV's tracking guideway point in the new coordinate system are obtained from the meters. Steps 5-9: Based on the point cloud data of the lightning protection wire in the new coordinate system, find the distance from the center of each tower along the transmission line. b The point cloud data of meters and along z Offset in the positive direction of the axis c The coordinates of the drone's flight path point where the tower and the conductor connect are obtained at the new coordinates. Steps 5-10: Based on the coordinates of the UAV's tracking traverse track points in the new coordinate system and the coordinates of the UAV's connection track points between the tower and the traverse in the new coordinate system, interpolation is performed at the discontinuities in the track points to obtain the coordinates of the continuous track points in the new coordinate system. Step 5-11: Convert the coordinates of the continuous track points in the new coordinate system to the geodetic coordinates of the continuous track points in the original coordinate system; Step 6: Convert the continuous track points to geodetic coordinates in the original coordinate system. x coordinate, y The coordinates are converted into latitude and longitude coordinates of continuous track points in the original coordinate system, thereby obtaining the location information of the UAV inspection track points; Step 7: Obtain the three-dimensional inspection path of the UAV based on the location information of the UAV inspection flight track points.

2. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 1, the planar position information and elevation information of the measured point are extracted using the laspy library of the Python language.

3. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 1, the power transmission line is divided into multiple conductor segments according to the tower location and the number of laser point cloud data, such that the number of laser point cloud data corresponding to each conductor segment is between 40 million and 80 million.

4. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 2, functions from the Open3D library are used to downsample the format-converted information to be processed.

5. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 2, the information to be processed is downsampled using uniform downsampling, voxel downsampling, or curvature downsampling.

6. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 3, the elevation threshold corresponding to each of the conductor segments is the sum of the average elevation of the conductor segment and a preset value.

7. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: For the transmission lines located in mountainous or rugged areas, in step 3, the information to be filtered is based on... x Axial direction coordinates or y After sorting along the axis, the system is divided into several smaller regions, and the elevation filtering process is performed within each of these smaller regions.

8. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 4, when performing segmented fitting, if a segment of the transmission line is in x The axial direction cannot form a relationship with y Functions in the axial direction are then transformed. x Axial direction and y Fitting along the axis direction and performing an inverse function transformation on the obtained function yields the corresponding linear equation; if a segment of the transmission line is in x Axial direction, y If no function can be formed in any of the axial directions, then the data should be re-segmented and then piecewise fitted.

9. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 5, the segmentation points of the piecewise linear equation are the tower locations.

10. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 5-1, the density of the measured point on the transmission line is obtained using the density function in the seaborn library, and then the position of the tower is determined using the density of the measured point on the transmission line.

11. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In steps 5-8, a The value of is 2. d The value of is determined by the voltage level of the transmission line. d The value can be 2, 3.5, 6 or 10.

12. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In steps 5-9, b The value is 10. c The value of is 2.

13. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In steps 5-10, linear interpolation is performed at points where the track points are discontinuous.

14. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 6, the geodetic coordinates of the continuous track points in the original coordinate system are obtained by using a four-parameter planar model. x coordinate, y The coordinates are then converted to the latitude and longitude coordinates of the continuous track points in the original coordinate system.

15. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 7, the location information of the drone's inspection flight path is input into the drone terminal for autonomous flight.

16. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 1, characterized in that: In step 5-2, based on the slope of the straight line segment... The rotation angle of the line segment is equal to Then utilize Calculate the coordinates of each measured point on the transmission line corresponding to the straight line segment in the new coordinate system, where, The value is , , The measured points on the transmission line corresponding to the straight line segment are in the original coordinate system. x coordinate, y coordinate, , The measured points on the transmission line corresponding to the straight line segment are in the new coordinate system. x coordinate, y coordinate.

17. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 16, characterized in that: In steps 5-11, using Calculate the geodetic coordinates of the continuous flight path points in the original coordinate system, where, The value is , , , The continuous waypoints in the original coordinate system x coordinate, y coordinate, z coordinate, , , The continuous waypoints in the new coordinate system x coordinate, y coordinate, z coordinate.

18. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 17, characterized in that: In step 6, using Calculate the latitude and longitude coordinates of the continuous waypoints in the original coordinate system, where, , The continuous track points are in the geodetic coordinates of the original coordinate system. x coordinate, y coordinate, , The latitude and longitude coordinates of continuous waypoints in the original coordinate system. , For translation parameters, For rotation parameters, This is the scale parameter.

19. The method for planning the three-dimensional inspection path of a UAV continuous tower base based on laser point cloud as described in claim 18, characterized in that: The translation parameters, rotation parameters, and scale parameters are calculated using two pairs of control points, and the coordinates of each pair of control points in the geodetic coordinate system and the coordinates in the latitude and longitude coordinate system are known.

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