Center point positioning and adaptive imaging course angle determining method for transmission conductor scattering spots

Abstract

The invention relates to the technical field of remote sensing monitoring of overhead transmission lines, in particular to a central point positioning and adaptive imaging course angle determining method for scattering spots of a transmission conductor. The central point positioning method of the transmission conductor scattering spots comprises the following steps: acquiring a positioning deviation of a synthetic aperture radar image for correcting a geometric positioning error of transmission conductor imaging; calculating a transmission conductor radar imaging simulation result according to the three-dimensional geographic coordinates of the transmission conductor and a distance Doppler positioning model; and solving a central point positioning result of the transmission conductor scattering spots according to a transmission conductor radar imaging simulation result. Therefore, the problem of accurate simulation positioning of the center point of the transmission conductor scattering spot in the radar remote sensing image is solved. Besides, the method can be used for simulating and calculating the accurate imaging position of the scattering spots of the transmission conductor under the condition of different SAR sensor course angles, the optimal course angle and the limit course angle are solved, and the method is used for unmanned aerial vehicle SAR cruise route planning and SAR satellite orbit design.

Description

Technical Field

[0001] The present application relates to the technical field of remote sensing monitoring of overhead power transmission lines, and in particular to a method for locating the center point of a scattering spot of a power transmission line and determining a heading angle of an adaptive imaging. Background Art

[0002] SAR (Synthetic Aperture Radar) is an active microwave remote sensing technology that can work even in bad weather conditions (such as rainy days, foggy days) or at night, so it has all-weather and all-day monitoring capabilities. Given that satellite-borne and UAV SAR have all-day and all-weather monitoring capabilities, wide-area real-time monitoring capabilities for transmission lines can be achieved. However, in SAR images with meter-level resolution, transmission lines sometimes present spot-like scattering features rather than linear texture features. Therefore, how to determine the relationship between the scattering spots of transmission lines and the three-dimensional geographical location of transmission lines is a current problem. At present, there is no relevant calculation method that can use the real geographical coordinates of transmission lines to simulate and calculate the imaging position of the scattering spots of transmission lines. When disasters such as ice cover, dancing, and floods occur, causing the transmission lines to break and change, it is impossible to use the three-dimensional coordinates of the transmission lines and the radar remote sensing image data of real-time monitoring to determine whether the transmission lines / ground lines are in normal condition.

[0003] Some literature points out that when the angle between the transmission line and the flight direction of the radar sensor exceeds 10 to 20 degrees, the texture characteristics of the transmission line scattering spots disappear (or become invisible). The main physical mechanism is that the angle between the radar incident direction and the cross section of the transmission line is too large, resulting in a sharp attenuation of the scattering signal. Microwave darkroom and simulation experiments have shown that when the radar wave incident direction is perpendicular to the extension direction of the transmission line, the radar wave signal scattered by the line reaches the strongest. However, there is a lack of relevant theories and methods for how to use this theory to determine the imaging position of the transmission line scattering spots. At present, it is impossible to determine the specific location of the transmission line scattering spot imaging through the geographical coordinates of the transmission line, radar image parameters and other information, making it difficult to guide radar remote sensing technology to monitor and evaluate the status of the transmission line. In particular, it is impossible to determine how the radar flight direction adapts to the extension direction of the transmission line, and under what radar sensor flight heading angle conditions, it can adapt to the imaging of the transmission line scattering spots. Summary of the invention

[0004] The present application provides a method for determining the center point of the transmission line scattering spot and the imaging adaptation heading angle, which solves the problem of how to accurately simulate and calculate the center point of the transmission line scattering spot. The center point positioning method can determine the orientation of the radar sensor heading angle, which can realize the radar imaging of the transmission line scattering spot, and estimate the radar sensor heading angle under the conditions of positive and negative limit angles, as well as the center point positioning of the transmission line scattering spot under the conditions of the optimal heading angle. This method solves the problem of how to determine the appropriate route for monitoring the transmission line, and is suitable for both the simulation calculation of the UAV SAR platform and the simulation calculation of the satellite-borne SAR.

[0005] The first aspect of the present application provides a method for locating the center point of a scattering spot of a power transmission line, including the following steps: obtaining the positioning deviation of a synthetic aperture radar image; correcting the geometric positioning error of the transmission line imaging according to the positioning deviation, calculating the radar imaging simulation formula of the transmission line according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line and the range Doppler positioning model; locating the center point of the scattering spot of the transmission line according to the radar imaging simulation formula. Locating the center point of the scattering spot of the transmission line according to the radar imaging simulation formula

[0006] Optionally, obtaining the positioning deviation of the synthetic aperture radar image includes: obtaining imaging parameters of the synthetic aperture radar image and the geographic coordinates of the ground control point in the synthetic aperture radar image; calculating the geometric positioning coordinates of the center point of the scattering spot of the power transmission line located according to the radar imaging simulation method of the ground control point in the radar coordinate system using the imaging parameters of the synthetic aperture radar image and the range Doppler positioning model; determining the positioning deviation of the synthetic aperture radar image based on the radar scattering imaging center point coordinates and the geometric positioning coordinates of the ground control point, wherein the radar scattering imaging center point coordinates of the ground control point are the coordinates of the extreme point of the scattering intensity within a preset range of the ground control point target, and the positioning deviation of the radar image is used to correct the geometric positioning of the synthetic aperture radar image.

[0007] Optionally, the radar imaging simulation result of the transmission line is calculated according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line and the range Doppler positioning model, including: obtaining the radar imaging coordinate point set of the transmission line in the radar coordinate system according to the three-dimensional geographic coordinate point set of the transmission line, the corrected geometric positioning error and the range Doppler model; obtaining the transmission line radar imaging simulation formula by a fitting method according to the radar imaging coordinate point set of the transmission line, the transmission line radar imaging simulation formula being a parabolic function or a hyperbolic function.

[0008] Optionally, locating the center point of the scattering spot of the transmission line according to the radar imaging simulation formula includes: solving the position of the center point of the scattering spot according to the transmission line radar imaging simulation formula and the condition that the center point of the scattering spot satisfies the parallel tangent equation in azimuth or has an extreme point in distance; when the transmission line radar imaging simulation formula is a parabolic equation, the coordinate point that satisfies the parallel tangent equation in azimuth is used as the center point of the scattering spot of the transmission line; when the transmission line radar imaging simulation formula is a hyperbolic equation, the coordinate point that satisfies the condition that an extreme point in distance exists is used as the center point of the scattering spot of the transmission line.

[0009] The second aspect of the present application provides a method for determining a heading angle of adaptive imaging of a scattering spot of a transmission line, comprising the following steps: horizontally rotating the extension direction of the conductor clockwise, simulating to obtain the geographical coordinates of the rotated transmission line, locating the center point of the scattering spot of the transmission line based on the center point positioning method of the scattering spot of the transmission line of the above embodiment, and taking the heading angle when the center point of the scattering spot of the transmission line is located at the mounting point of the transmission line as the negative direction limit heading angle of the adaptive imaging of the scattering spot of the transmission line; horizontally rotating the extension direction of the conductor counterclockwise, simulating to obtain the geographical coordinates of the rotated transmission line, and locating the center point of the scattering spot of the transmission line based on the center point positioning method of the scattering spot of the transmission line of the above embodiment. The center point positioning method of the scattering spot locates the center point of the scattering spot of the transmission line, and the heading angle when the center point of the transmission line spot is located at the transmission line mounting point is used as the positive direction limit heading angle of the transmission line scattering spot adaptive imaging; when the extension direction of the horizontal rotating wire is consistent with the flight direction of the radar sensor, the geographical coordinates of the rotated transmission line are obtained by simulation, and the center point of the scattering spot of the transmission line based on the center point positioning method of the scattering spot of the transmission line of the above embodiment is located, and the angle when the center point of the scattering spot of the transmission line is located at the middle position of the mounting points at both ends of the transmission line is used as the optimal heading angle of the transmission line scattering spot adaptive imaging.

[0010] Optionally, the method for calculating the negative direction limit heading angle is: calculate the distance from the center point of the transmission line scattering spot to the mounting points at both ends of the transmission line; the heading angle when the distance between the center point of the transmission line spot and the mounting point at the end of the clockwise rotating line extension direction is zero is used as the negative direction limit heading angle of the transmission line scattering spot adaptive imaging.

[0011] Optionally, a method for calculating the positive direction limit heading angle includes: the method for calculating the positive direction limit heading angle includes the following steps: calculating the distance from the center point of the scattering spot of the transmission line to the mounting points at both ends of the transmission line; the heading angle when the distance between the center point of the transmission line spot and the mounting point at the end of the counterclockwise rotating line extension direction is zero is used as the positive direction limit heading angle for the adaptive imaging of the scattering spot of the transmission line.

[0012] Optionally, the method for calculating the optimal heading angle of the transmission line scattering spot adaptive imaging is: determining the angle offset of the transmission line scattering spot adaptive imaging according to the center point of the transmission line scattering spot; and calculating the optimal heading angle according to the angle offset and the current angle of the transmission line scattering spot adaptive imaging.

[0013] The third aspect of the present application provides a device for locating the center point of a scattering spot of a transmission line. The device is applied to a sensor platform and includes: an acquisition module for acquiring the positioning deviation of a synthetic aperture radar image; a calculation module for correcting the geometric positioning error of the transmission line imaging according to the positioning deviation, and calculating the radar imaging simulation formula of the transmission line according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line and the range Doppler positioning model; a positioning module for locating the center point of the scattering spot of the transmission line according to the radar imaging simulation formula.

[0014] In a fourth aspect, an embodiment of the present application provides a device for determining a heading angle of adaptive imaging of a scattering spot of a transmission line, and the device is applied to a data center or a sensor scheduling platform, comprising: a first determining module, for horizontally rotating the extension direction of the conductor clockwise, simulating and obtaining the geographical coordinates of the rotated transmission line, locating the center point of the scattering spot of the transmission line based on the center point positioning device of the scattering spot of the transmission line, and taking the heading angle when the center point of the scattering spot of the transmission line is located at the mounting point of the transmission line as the negative direction limit heading angle of the adaptive imaging of the scattering spot of the transmission line; a second determining module, for horizontally rotating the extension direction of the conductor counterclockwise, simulating and obtaining the geographical coordinates of the rotated transmission line; The third determining module is used for simulating and obtaining the geographical coordinates of the rotated transmission line when the extension direction of the horizontal rotating wire is consistent with the flight direction of the radar sensor, locating the center point of the transmission line scattering spot based on the center point positioning device of the transmission line scattering spot, and taking the angle when the center point of the transmission line scattering spot is located at the middle position of the mounting points at both ends of the transmission line as the optimal heading angle for the adaptive imaging of the transmission line scattering spot.

[0015] Therefore, this application has at least the following beneficial effects:

[0016] The embodiment of the present application can accurately simulate and locate the center point position of the overhead transmission conductor / ground line radar imaging scattering spot, and correct the positioning deviation of the synthetic aperture radar image based on the ground image control point, so that the geographical coordinates of the transmission line can be accurately simulated to the radar imaging coordinate system, and the center point positioning of the transmission line scattering spot in the SAR image is realized with high precision. The center point position of the transmission line scattering spot is obtained by using the function extreme value characteristics of the transmission line simulation formula, and the transmission line geographical coordinates obtained by rotating the extension direction of the simulated transmission line clockwise and counterclockwise, and the center point positioning method of the transmission line scattering spot of the present application can determine the positive and negative limit values ​​of the heading angle of the radar sensor, that is, the heading azimuth angle outside the limit value condition will not form the transmission line scattering spot. At the same time, the center point position of the transmission line scattering spot under the optimal heading angle condition can be simulated and calculated. It can be used for the application scenario of SAR satellite remote sensing monitoring of transmission lines, especially for planning the flight routes of drones and space-borne SAR, and for adaptive imaging of transmission line scattering spots. On the other hand, when the route planning software and satellite orbit analysis software plan the flight route of the SAR sensor, the present application can realize the accurate simulation positioning of the center position of the transmission line scattering spot, thereby providing a theoretical basis for the actual measurement of the transmission line scattering spot, and providing a reference for early warning when the transmission line scattering spot has a large position deviation under disaster conditions such as transmission line breakage and wind deviation.

[0017] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0019] Figure 1 A flow chart of a method for locating the center point of a scattering spot of a power transmission line provided according to an embodiment of the present application;

[0020] Figure 2 An example diagram of a three-dimensional point cloud of power transmission lines in a certain area provided according to an embodiment of the present application;

[0021] Figure 3 A schematic diagram of a transmission line simulation function provided according to an embodiment of the present application;

[0022] Figure 4 A diagram for solving the center point of transmission line bunching imaging based on an additional constraint condition of an azimuth tangent provided according to an embodiment of the present application;

[0023] Figure 5 A diagram showing simulation results of all power transmission lines in a certain area under TSX and CSK images according to an embodiment of the present application;

[0024] Figure 6 A flow chart of a method for determining a heading angle of adaptive imaging of scattered spots of a transmission line provided in accordance with an embodiment of the present application;

[0025] Figure 7 A schematic diagram of the angle between the satellite heading and the direction of the transmission line provided according to an embodiment of the present application;

[0026] Figure 8 This is a simulation function of a power transmission line at different heading angles in a certain area and an example diagram of the imaging center point under additional azimuth constraints provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0028] The following describes the center point positioning method and simulation application method of the transmission line scattering spot of the embodiment of the present application with reference to the accompanying drawings. In view of the problems mentioned in the above background technology, the present application provides a method for positioning the center point of the transmission line scattering spot, in which the center point position of the overhead transmission conductor / ground line radar imaging scattering spot can be accurately simulated and positioned, and the positioning deviation of the synthetic aperture radar image can be corrected based on the ground image control point, so that the geographical coordinates of the transmission line can be accurately simulated into the radar imaging coordinate system, and the center point positioning of the transmission line scattering spot in the SAR image with high precision is realized.

[0029] Specifically, Figure 1 A schematic flow chart of a method for locating the center point of a scattering spot of a power transmission line provided in an embodiment of the present application.

[0030] like Figure 1 As shown, the method for locating the center point of the transmission line scattering spot includes the following steps:

[0031] In step S101, the positioning deviation of the synthetic aperture radar image is obtained.

[0032] In the embodiment of the present application, the transmission conductor is responsible for transmitting electrical energy, while the transmission ground wire mainly plays a protective role against lightning strikes and some of the internally wrapped optical cables have communication capabilities to ensure the safe operation of the transmission line.

[0033] In one embodiment of the present application, obtaining the positioning deviation of a synthetic aperture radar image includes: obtaining imaging parameters of the synthetic aperture radar image and the geographic coordinates of a ground control point in the synthetic aperture radar image; calculating the geometric positioning coordinates of the geographic coordinates of the ground control point in the radar coordinate system using the imaging parameters of the synthetic aperture radar image and the range Doppler positioning model; determining the positioning deviation of the synthetic aperture radar image based on the radar scattering imaging center point coordinates and the geometric positioning coordinates of the ground control point, wherein the radar scattering imaging center point coordinates of the ground control point are the coordinates of the scattering intensity extreme point within a preset range of the ground control point target, and the positioning deviation of the radar image is used to correct the geometric positioning of the synthetic aperture radar image.

[0034] It can be understood that the embodiment of the present application can obtain the coordinates of the ground control point actually measured by the transmission line; determine the geometric positioning coordinates of the transmission line in the radar coordinate system using the imaging parameters of the synthetic aperture radar image and the range Doppler model; based on the high-precision geographic coordinates of the ground image control point C actually measured, mark the ellipsoid coordinates of the point as C (B,L,H) ;

[0035] Using SAR image imaging parameters and range Doppler model, we can obtain the sub-pixel pixel coordinates C of point C in the SAR coordinate system. g(a,r) ; Through more than 10 times oversampling, the maximum value search method is used to obtain the sub-pixel level precision coordinates C of the extreme point of scattering intensity within the preset range of the control point C target s(a,r) ; Compare the sub-pixel center coordinates C calculated using the Doppler model and the measured geographic coordinates of the control point C g(a,r) , and the sub-pixel center coordinate C obtained from the extreme point of scattering intensity s(a,r) , obtain the deviation of the sub-pixel accuracy of the SAR image in azimuth and range directions ε (a,r) :ε (a,r) =C s(a,r) -C g(a,r) ;

[0036] In step S102, the geometric positioning error of the transmission line imaging is corrected according to the positioning deviation, and the radar imaging simulation formula of the transmission line is calculated according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line and the range Doppler positioning model.

[0037] In the embodiment of the present application, the ellipsoid coordinate expression of the geographical coordinate point set of the transmission line i can be recorded as i [BLH] , the geocentric coordinate system expression of the point set is recorded as i [XYZ] ; Using SAR image parameters and range Doppler model, taking into account the azimuth and range offset ε (a,r) , we get the imaging point set of the transmission line in the radar coordinate system: i [ar] .

[0038] Specifically, the embodiment of the present application can be combined with a specific embodiment of the transmission line area implementation process to describe step S101 of the embodiment of the present application in detail, including the following steps:

[0039] According to the three-dimensional point cloud of a certain transmission line area, Figure 2 As shown, there are 8 transmission lines in the area, so i = A, B, C, D, E, F, M, N. Take the high-precision geographic coordinates C of a typical ground image control point street lamp C. (X,Y,z) , the right angle position vector in the geocentric space is denoted by R C (C X ,C Y ,C Z ) T ; Corresponding to the imaging time t of point C i The instantaneous position vector of the SAR satellite at time is in the geocentric rectangular coordinate system, and the position vector R S Denoted as (S X ,S Y ,S Z ) T ;

[0040] R C With R S Satisfies the range Doppler equation:

[0041]

[0042] Among them, V S is the velocity vector of the SAR sensor S, which contains components in three directions: and λ is the radar wavelength, f d t i The frequency offset of the radar echo signal at time t, R i Then it is point Ct i Slant range to the satellite at any moment;

[0043] Using the cm-level precision orbit data of SAR satellites, R in Eq. i It can be accurately located to the cm level through iterative solution, and the corresponding imaging time t i The accuracy can be better than 0.1 nanosecond; C (X,Y,Z) According to the range Doppler equation, find the R and t corresponding to the point i , and calculate the reference coordinate value C in the radar coordinate system (a,r) , accurate to the sub-pixel level, as shown below:

[0044]

[0045] Among them, R 0is the slant distance of the close-range point corresponding to the first column of pixels in the SAR image, ρ r is the radar azimuth spatial resolution. 0 is the starting sampling time of the first row of pixels of the SAR image in azimuth, Az is the number of views in azimuth, and PRF is the radar pulse repetition frequency;

[0046] Furthermore, the embodiment of the present application uses local oversampling, such as using the coordinate value of the reference point C (C a ,C r ) as the center, such as selecting a 20*20 window, oversampling 10 times, and using the maximum search method under the oversampled window to traverse and find the maximum point of the scattering intensity, the radar scattering imaging center point C of the reference point C is obtained. g Pixel coordinates Compare the sub-pixel center coordinates (C) calculated by using the Doppler model and the measured geographic coordinates of the image control point C a ,C r ), and the sub-pixel center coordinates obtained by the maximum value search method Obtaining the positioning deviation of SAR image sub-pixel accuracy: ε (a,r) =C s(a,r) -C g(a,r)

[0047] Further, the positioning deviation can be obtained under the TSX image of a certain area

[0048] The positioning deviation can be obtained under the CSK image of a certain area.

[0049] The embodiment of the present application can utilize SAR image imaging parameters and range Doppler model, and take into account the deviation ε in azimuth and range (a,r) , find the imaging point set of each transmission line three-dimensional point set in the SAR coordinate system: i [ar] .

[0050] In one embodiment of the present application, a radar imaging simulation result of a transmission line is calculated based on a corrected geometric positioning error, a three-dimensional geographic coordinate point set of the transmission line, and a range Doppler positioning model, including: obtaining a radar imaging coordinate point set of the transmission line in a radar coordinate system based on the three-dimensional geographic coordinate point set of the transmission line, the corrected geometric positioning error, and the range Doppler model; obtaining a radar imaging simulation formula of the transmission line by a fitting method based on the radar imaging coordinate point set of the transmission line, wherein the radar imaging simulation formula of the transmission line is a parabolic function or a hyperbolic function.

[0051] In the embodiment of the present application, the transmission line radar imaging simulation formula can be a quadratic polynomial function or a hyperbolic function. The embodiment of the present application can calculate the azimuth coordinates and range coordinates of any point on the transmission line in the radar coordinate system according to the imaging parameters of the synthetic aperture radar image and the range Doppler model; and determine the equation coefficients of the target simulation formula according to the azimuth coordinates and the range coordinates.

[0052] Specifically, for any transmission line i, the simulation formula f of the imaging point set in the radar coordinate system is obtained: i (j a ), Figure 3 Simulate the function f for the transmission line i i (j a ) schematic diagram. If the simulation type f i (j a ) is a quadratic polynomial function, where j a is the azimuth coordinate of any point j on the wire in the radar coordinate system, f i (j a ) is the distance coordinate of any point j on the wire i in the radar coordinate system, and the polynomial coefficient β is obtained. 1 ,β 2 ,β 3 ;

[0053] In the TSX image of a certain area, take transmission line A as an example.

[0054] In the CSK image of a certain area, take the transmission line A as an example.

[0055] In step S103, the center point of the scattering spot of the transmission line is located according to the radar imaging simulation.

[0056] In the embodiment of the present application, the position of the center point of the scattering spot can be solved according to the transmission line radar imaging simulation formula and the condition that the center point of the scattering spot satisfies the parallel tangent equation in the azimuth direction or the condition that the extreme point exists in the distance direction; when the transmission line radar imaging simulation formula is a parabolic equation, the coordinate point that satisfies the parallel tangent equation in the azimuth direction is used as the center point of the transmission line scattering spot; when the transmission line radar imaging simulation formula is a hyperbolic equation, the coordinate point that satisfies the condition that the extreme point exists in the distance direction is used as the center point of the transmission line scattering spot.

[0057] Specifically, the embodiment of the present application can use the simulation type f i (j a ) and the additional constraint condition formula of the tangent line in the azimuth direction, and obtain the coordinates S of the center of the transmission line imaging spot (a,r) , specifically including the following steps:

[0058] If the simulation function is set to simulation formula f i (j a ) is a quadratic polynomial function, the additional constraint f based on the azimuthal tangent equation is i ′(j a )=0;

[0059] like Figure 4 As shown, according to f i ′(j a )=0 to obtain the simulation formula f i (j a ) under this constraint condition is the simulation result S of the center point of the SAR scattering spot of the transmission line. (a,r) :

[0060] Output the maximum value S a and the corresponding S r , that is, the distance to the extreme point S (a,r) , is the simulation calculation result of the center point of the SAR scattering spot of the transmission line;

[0061] In the TSX image of a certain area, take transmission line A as an example.

[0062] In the CSK image of a certain area, take the transmission line A as an example.

[0063] like Figure 5 As shown in the figure, the simulation results of all transmission lines in a certain area under TSX and CSK images are shown. Figure 5 a is the simulation of the transmission line i under the TSX satellite in the SAR image. i (j a ), so i = A, B, C, D, E, F, M, N, Figure 5 b is the simulation diagram of 8 transmission lines under the CSK satellite; Figure 5 The enlarged partial image in the middle is a schematic diagram of solving the center point of the transmission line bunching imaging under the additional azimuth constraint condition. Figure 5 a is the TSX satellite in a certain area f i ′(j a )=0, the imaging center point, Figure 5 b is the CSK satellite f i ′(j a )=0 The circle is the calculated simulation result of the center coordinates of the scattering spot, and the bottom is the scattering spot area corresponding to the transmission line.

[0064] Furthermore, the embodiment of the present application can be based on the transmission line SAR scattering spot center coordinate S in the radar coordinate system (a,r), find its location mapped to the transmission line in geographic coordinates, that is, the three-dimensional coordinates S of the point (B,L,H) .

[0065] In one embodiment of the present application, after locating the center point of the scattering spot of the transmission line according to the radar imaging simulation method, when simulating the change of the SAR heading angle, the embodiment of the present application can project the three-dimensional point cloud coordinates of the transmission line along the vertical line to the horizontal plane XOY plane in the spatial rectangular coordinate system, and obtain the expression y=k of the transmission line in the plane. 1 *x+k 2 , where (x, y) is the vertical and horizontal coordinates of the transmission line in the local rectangular coordinate system, and the angle ξ between the extension direction of the transmission line and the north direction is calculated based on the expression y: ξ = arctan (k 1 ).

[0066] Rotate the conductor extension direction clockwise horizontally by an angle μ so that the angle between the transmission line extension direction and the north direction reaches ξ-μ degrees; rotate the conductor extension direction counterclockwise horizontally by an angle μ so that the angle between the transmission line extension direction and the north direction reaches ξ+μ degrees.

[0067] Simulate and calculate the expression y of the transmission line under the angle ξ±μ. According to the calculation efficiency and calculation requirements, a number of points are selected with a point cloud interval of 0.1 to 5m to form a point set Q. [xy] ; Keep the elevation information of the corresponding number of the conductor point cloud unchanged, and obtain the three-dimensional point cloud data Q of the transmission line at ξ±μ angles [xyz] , the rotated geographical coordinates of the transmission line are obtained by simulation, and Q [xyz] Transform the point set Q into the ellipsoid coordinate system [BLH] .

[0068] Furthermore, the embodiment of the present application can correct the SAR image positioning deviation based on the ground image control points, and then use the range Doppler model to calculate the point set Q [BLH] Imaging point set Q in radar image [ar] Simulation results;

[0069] Based on Q [ar] For the transmission line i, obtain the simulation formula f of the imaging point set in the radar coordinate system i (j a ); using f i (j a ) and the additional constraint condition formula of the azimuth tangent are used to obtain the imaging position of the center point of the SAR scattering spot of the transmission line when the transmission line strike angle is ξ+μ, which is the simulation application of the imaging point position of the center point of the scattering spot.

[0070] According to the method for locating the center point of the scattering spot of a transmission line proposed in an embodiment of the present application, the positioning deviation of the synthetic aperture radar image is corrected based on the ground image control points, and the imaging point set in the synthetic aperture radar image is simulated, so as to realize the simulation of the coordinates of the center points of the SAR scattering spots of different transmission lines, thereby improving the positioning accuracy of the center points of the scattering spots of the transmission lines in the SAR images, and can be used in the application scenario of SAR satellite remote sensing monitoring of transmission lines.

[0071] Secondly, the embodiment of the present application also proposes a method for determining a heading angle of a transmission line scattering spot adaptive imaging, and the method for determining a heading angle of a transmission line scattering spot adaptive imaging comprises the following steps:

[0072] In step S601, the extension direction of the conductor is rotated horizontally clockwise to simulate and obtain the geographical coordinates of the rotated transmission line. The center point of the transmission line scattering spot is located based on the center point positioning method of the transmission line scattering spot of the above embodiment. The heading angle when the center point of the transmission line spot is located at the transmission line mounting point is used as the negative direction limit heading angle of the transmission line scattering spot adaptive imaging.

[0073] In step S602, the extension direction of the conductor is rotated counterclockwise horizontally to simulate and obtain the geographical coordinates of the rotated transmission line. The center point of the transmission line scattering spot is located based on the center point positioning method of the transmission line scattering spot of the above embodiment, and the heading angle when the center point of the transmission line spot is located at the transmission line mounting point is used as the positive direction limit heading angle of the transmission line scattering spot adaptive imaging.

[0074] It is understandable that the embodiment of the present application can generate an imaging point set simulation result of the transmission line in a radar coordinate system by rotating the extension direction of the transmission line clockwise or counterclockwise based on the target direction.

[0075] The target direction may be the north direction.

[0076] It can be understood that, in the spatial rectangular coordinate system, the three-dimensional point cloud coordinates of the transmission line are projected to the XOY plane, and the expression y of the transmission line in the plane is fitted, where (x, y) are the vertical and horizontal coordinates of the transmission line in the local rectangular coordinate system, and the angle ξ between the extension direction of the transmission line and the north direction is calculated; the heading angle parameter θ of the SAR image is obtained, and the angle η between the wire direction ξ and the heading angle θ is calculated: η=θ-ξ. Figure 7 a shows the original angle between the wire direction and heading angle in a certain area, η = 4°;

[0077] Set the rotation angle correction value μ in a gradient of 1 to 5°, with clockwise as the negative direction and counterclockwise as the positive direction. i , so that η±μ i In the range of ±20°, a series of different values ​​of μ are obtained. i; Rotate the extension direction of the transmission line clockwise or counterclockwise by an angle μ based on the north direction i , so that the transmission line angle is ξ±μ i degree, simulate the expression y of the transmission line, keep the point cloud elevation value unchanged, and obtain the transmission line at ξ±μ i 3D point cloud dataset under different angles.

[0078] Furthermore, the embodiment of the present application can rotate the extension direction of the transmission line by an angle μ clockwise or counterclockwise based on the north direction. i , so that the transmission line angle is ξ±μ i Degree, calculate the expression y obtained by projecting the transmission line on the horizontal plane, as Figure 7 As shown in b; keep the point cloud elevation value unchanged and obtain the transmission line at ξ±μ i 3D point cloud dataset Q [BLH] ;

[0079] Based on the method for locating the center point of the scattering spot of the transmission line described in the above embodiment, the coordinates of the center point of the scattering spot of the transmission line are located, and the coordinate positions of the mounting points at both ends of the transmission line are obtained.

[0080] The embodiment of the present application can obtain the three-dimensional coordinate point cloud data of the transmission line at the angle ξ±μ obtained by simulation, and obtain the strike angle of a single transmission line as ξ±μ i When the transmission line SAR scattering spot center coordinates are i Corresponding Get ξ±μ i The three-dimensional coordinate values ​​of the mounting points at both ends of the transmission line at the angle

[0081] Furthermore, the embodiment of the present application can obtain the sub-pixel-level geometric positioning coordinates C of the ground image control point C obtained by field measurement using SAR image imaging parameters and the range Doppler model in the radar coordinate system. g(a,r) ; Through local oversampling and maximum value search method, the coordinates C of the imaging center point C in the SAR image with sub-pixel accuracy are obtained s(a,r) ; Compare the geometric positioning coordinates C of the image control point C g(a,r) and the imaging center coordinates C s(a,r) , obtain the geometric positioning deviation ε of the SAR image sub-pixel accuracy (a,r) ; Using SAR image parameters and range Doppler model, and taking into account the image geometric positioning deviation, we can obtain Imaging coordinates of three-dimensional coordinates in radar coordinate system

[0082] In the embodiment of the present application, the positive direction can be counterclockwise to identify the positive limit heading angle when the coordinates of the center point of the scattering spot of the transmission line reach the coordinates of the mounting point; the negative direction can be clockwise to identify the negative limit heading angle when the coordinates of the center point of the scattering spot of the transmission line reach the coordinates of the mounting point; the limit value range of the satellite heading angle is determined according to the positive limit heading angle and the negative limit heading angle, specifically:

[0083] In the embodiment of the present application, the counterclockwise direction is taken as the positive direction, and after the transmission line extension direction rotation angle μ is obtained by simulation, the coordinate point set of the transmission line three-dimensional point cloud data in the radar coordinate system is obtained, and the imaging position of the center point of the SAR scattering spot of the transmission line in the radar coordinate system is obtained. When it reaches the mounting point at one end of the line, it is the SAR satellite limit heading angle θ in the counterclockwise direction. m ; Taking the clockwise direction as the negative direction, the simulation obtains the coordinate point set of the transmission line three-dimensional point cloud data in the radar coordinate system after the extension direction of the transmission line is rotated by an angle μ, and the imaging position of the center point of the SAR scattering spot of the transmission line in the radar coordinate system is obtained. When it reaches the mounting point at one end of the line, it is the SAR satellite limit heading angle θ in the clockwise direction. n ;

[0084] In the actual implementation process, the calculation method of the negative direction limit heading angle is: calculate the distance from the center point of the transmission line scattering spot to the mounting points at both ends of the transmission line; when the distance between the center point of the transmission line spot and the mounting point at the end of the clockwise rotating line extension direction is zero, the heading angle is used as the negative direction limit heading angle of the transmission line scattering spot adaptive imaging. The calculation method of the positive direction limit heading angle includes: the calculation method of the positive direction limit heading angle includes the following steps: calculate the distance from the center point of the transmission line scattering spot to the mounting points at both ends of the transmission line; when the distance between the center point of the transmission line spot and the mounting point at the end of the counterclockwise rotating line extension direction is zero, the heading angle is used as the positive direction limit heading angle of the transmission line scattering spot adaptive imaging.

[0085] Based on the above embodiment, the coordinate positions of the mounting points at both ends of the transmission line are obtained. When the coordinates of the center point of the scattering spot Arrived at the side tower mounting point The SAR satellite limit heading angle θ in the counterclockwise direction is m ; Coordinates of the center of the scattering spot Arrived at the side tower mounting point When , the SAR satellite heading angle limit value θ on the other side can be obtained n .

[0086] In step S103, when the extension direction of the horizontal rotating conductor is consistent with the flight direction of the radar sensor, the geographical coordinates of the rotated transmission line are obtained by simulation, and the center point of the transmission line scattering spot is located based on the center point positioning method of the transmission line scattering spot of the above embodiment, and the angle when the center point of the transmission line scattering spot is located at the middle position of the mounting points at both ends of the transmission line is used as the optimal heading angle for adaptive imaging of the transmission line scattering spot.

[0087] Specifically, when the extension direction ξ of the wire is completely consistent with the heading angle θ of the satellite, the center point of the SAR scattering spot of the transmission line is located in the middle of the two mounting points, which is the optimal heading angle; when the extension direction of the transmission line is rotated to a suitable angle μ k , when the imaging position of the center point of the SAR scattering spot of the transmission line in the radar coordinate system is located in the middle of the two wire mounting points, the satellite heading angle under this condition is the optimal heading angle;

[0088] The following embodiments of the present application take the transmission line F as an example. Figure 8 is the simulation function of the transmission line at different heading angles in a certain area F (j a ) and the imaging center under the additional constraints in azimuth. In this area, η = -4°, the gradient is 4°, and μ is obtained. i They are +10, +6, 0, -4, -10, -14 respectively, making θ -14, -10, 4, 0, 6, 10. Figure 8 It can be seen from a that when the angle θ between the conductor and the heading angle is ±10°, the calculated beam spot is not on the three-dimensional point set of the conductor. Therefore, under this angle, SAR cannot obtain an effective imaging center. Correspondingly, under the TSX image of this area, the angle of the conductor scattering spot imaging should be close to η=+6~-12°, and the corresponding θ m =+10,θ n =-8°. Figure 8 b shows that when the angle η between the conductor and the heading angle is ±10°, the beam spots calculated under the CSK image are all on the three-dimensional point set of the conductor, and the SAR can obtain the effective imaging center; therefore, under the CSK image in this area, the angle of the conductor scattering spot imaging should be close to η=+10~-13°, and the corresponding θ m =+14,θ n =-9°.

[0089] According to the heading angle determination method for adaptive imaging of the scattering spot of the transmission line proposed in the embodiment of the present application, by rotating the extension direction of the transmission line relative to the target direction, the imaging point set of the transmission line in the radar coordinate system is simulated, so as to locate the coordinates of the center point of the scattering spot of the transmission line. By calculating the coordinate positions of the mounting points at both ends and the coordinates of the center point of the scattering spot of the transmission line, the optimal value and the limit value range of the satellite heading angle can be determined. While realizing the simulation of the center point position of the scattering spot of the transmission line under different heading angles, the flight route of the SAR sensor can be optimized by determining the optimal observation conditions, including the route of the UAV and the orbital plane design of the satellite.

[0090] In addition, an embodiment of the present application also provides a device for locating the center point of a transmission line scattering spot, which is applied to a sensor platform and includes: an acquisition module, used to acquire the positioning deviation of a synthetic aperture radar image; a calculation module, used to correct the geometric positioning error of the transmission line imaging according to the positioning deviation, and calculate the radar imaging simulation formula of the transmission line according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line and the range Doppler positioning model; a positioning module, used to locate the center point of the transmission line scattering spot according to the radar imaging simulation formula.

[0091] The embodiment of the present application also provides a device for determining the heading angle of adaptive imaging of the scattering spot of a transmission line, which is applied to a data center or a sensor scheduling platform, and includes: a first determination module, which is used to horizontally rotate the extension direction of the conductor clockwise, simulate and obtain the geographical coordinates of the rotated transmission line, locate the center point of the scattering spot of the transmission line based on the center point positioning device of the scattering spot of the transmission line, and use the heading angle when the center point of the scattering spot of the transmission line is located at the mounting point of the transmission line as the negative direction limit heading angle of the adaptive imaging of the scattering spot of the transmission line; a second determination module, which is used to horizontally rotate the extension direction of the conductor counterclockwise, simulate and obtain the geographical coordinates of the rotated transmission line , based on the above-mentioned transmission line scattering spot center point positioning device, the center point of the transmission line scattering spot is positioned, and the heading angle when the center point of the transmission line spot is located at the transmission line mounting point is used as the positive direction limit heading angle of the transmission line scattering spot adaptive imaging; the third determination module is used to simulate and obtain the geographical coordinates of the rotated transmission line when the extension direction of the horizontal rotating wire is consistent with the flight direction of the radar sensor, and based on the above-mentioned transmission line scattering spot center point positioning device, the center point of the transmission line scattering spot is positioned, and the angle when the center point of the transmission line scattering spot is located at the middle position of the mounting points at both ends of the transmission line is used as the optimal heading angle of the transmission line scattering spot adaptive imaging.

[0092] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0093] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0094] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0095] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for locating the center point of a scattering spot of a transmission line, characterized in that: The following steps are involved: Obtaining positioning deviation of synthetic aperture radar images; Correcting the geometric positioning error of the transmission line imaging according to the positioning deviation, and calculating the radar imaging simulation formula of the transmission line according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line and the range Doppler positioning model; The center point of the scattering spot of the transmission line is located according to the radar imaging simulation method.

2. The method for locating the center point of the scattering spot of a power transmission line according to claim 1, characterized in that: Get the positioning deviation of synthetic aperture radar imagery, including: Acquiring imaging parameters of the synthetic aperture radar image and geographic coordinates of ground control points in the synthetic aperture radar image; Calculating the geometric positioning coordinates of the geographic coordinates of the ground control point in the radar coordinate system using the imaging parameters of the synthetic aperture radar image and the range Doppler positioning model; The positioning deviation of the synthetic aperture radar image is determined based on the radar scattering imaging center point coordinates of the ground control point and the geometric positioning coordinates, wherein the radar scattering imaging center point coordinates of the ground control point are the coordinates of the extreme point of scattering intensity within a preset range of the ground control point target, and the positioning deviation of the radar image is used to correct the geometric positioning of the synthetic aperture radar image.

3. The method for locating the center point of the scattering spot of a power transmission line according to claim 1, characterized in that: Calculating the radar imaging simulation result of the transmission line according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line and the range Doppler positioning model, including: Obtaining a radar imaging coordinate point set of the transmission line in a radar coordinate system according to the three-dimensional geographic coordinate point set of the transmission line, the corrected geometric positioning error and the range Doppler model; A transmission line radar imaging simulation formula is obtained by fitting the radar imaging coordinate point set of the transmission line, and the transmission line radar imaging simulation formula is a parabolic function or a hyperbolic function.

4. The method for locating the center point of the scattering spot of a power transmission line according to claim 3, characterized in that: Locating the center point of the transmission line scattering spot according to the radar imaging simulation method includes: Solve the position of the center point of the scattering spot according to the transmission line radar imaging simulation formula and the condition that the center point of the scattering spot satisfies the parallel tangent equation in the azimuth direction or has an extreme point in the distance direction; When the transmission line radar imaging simulation equation is a parabolic equation, a coordinate point satisfying the azimuth parallel tangent equation condition is used as the center point of the transmission line scattering spot; When the transmission line radar imaging simulation formula is a hyperbolic equation, a coordinate point satisfying the condition of the existence of a distance extreme point is used as the center point of the transmission line scattering spot.

5. A method for determining the heading angle of transmission line scattering spot adaptive imaging, characterized in that: The following steps are involved: Rotate the extension direction of the conductor clockwise horizontally to simulate and obtain the geographical coordinates of the rotated transmission line. Locate the center point of the transmission line scattering spot based on the center point positioning method of the transmission line scattering spot according to any one of claims 1 to 4. Use the heading angle when the center point of the transmission line spot is located at the transmission line mounting point as the negative direction limit heading angle of the transmission line scattering spot adaptive imaging; Rotate the extension direction of the conductor counterclockwise horizontally, simulate and obtain the geographical coordinates of the rotated transmission line, locate the center point of the transmission line scattering spot based on the center point positioning method of the transmission line scattering spot according to any one of claims 1 to 4, and use the heading angle when the center point of the transmission line spot is located at the transmission line mounting point as the positive direction limit heading angle of the transmission line scattering spot adaptive imaging; When the extension direction of the horizontal rotating conductor is consistent with the flight direction of the radar sensor, the geographical coordinates of the rotated transmission line are obtained by simulation, and the center point of the transmission line scattering spot is located based on the center point positioning method of the transmission line scattering spot described in any one of claims 1 to 4, and the angle when the center point of the transmission line scattering spot is located at the middle position of the mounting points at both ends of the transmission line is used as the optimal heading angle for adaptive imaging of the transmission line scattering spot.

6. The method for determining the heading angle of transmission line scattered spot adaptive imaging according to claim 5, characterized in that: The calculation method of the negative direction limit heading angle is: Calculating the distance from the center point of the scattering spot of the transmission wire to the mounting points at both ends of the transmission wire; The heading angle when the distance between the center point of the transmission line spot and the mounting point at the end of the clockwise rotating wire extension direction is zero is used as the negative direction limit heading angle of the transmission line scattering spot adaptive imaging.

7. The method for determining the heading angle of transmission line scattered spot adaptive imaging according to claim 5, characterized in that: The method for calculating the positive direction limit heading angle comprises the following steps: Calculating the distance from the center point of the scattering spot of the transmission wire to the mounting points at both ends of the transmission wire; The heading angle when the distance between the center point of the transmission line spot and the mounting point at the end of the counterclockwise rotating line extension direction is zero is used as the positive direction limit heading angle of the transmission line scattering spot adaptive imaging.

8. The method for determining the heading angle of transmission line scattered spot adaptive imaging according to claim 5, characterized in that: The calculation method of the optimal heading angle of the transmission line scattering spot adaptive imaging is: Determining the angular offset of the transmission line scattering spot adaptive imaging according to the center point of the transmission line scattering spot; The optimal heading angle is calculated based on the angle offset and the current angle of the adaptive imaging of the transmission line scattering spot.

9. A device for locating the center point of a scattering spot of a power transmission line, characterized in that: The device is applied to a sensor platform, including: An acquisition module, used to obtain the positioning deviation of the synthetic aperture radar image; A calculation module, used for correcting the geometric positioning error of the transmission line imaging according to the positioning deviation, and calculating the radar imaging simulation formula of the transmission line according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line and the range Doppler positioning model; A positioning module is used to locate the center point of the scattering spot of the transmission line according to the radar imaging simulation method.

10. A device for determining heading angle of transmission line scattered spot adaptive imaging, characterized in that: The device is applied to a data center or a sensor scheduling platform, including: The first determination module is used to horizontally rotate the extension direction of the conductor clockwise to simulate and obtain the geographical coordinates of the rotated transmission line, locate the center point of the transmission line scattering spot based on the center point positioning device of the transmission line scattering spot according to claim 9, and use the heading angle when the center point of the transmission line spot is located at the transmission line mounting point as the negative direction limit heading angle of the transmission line scattering spot adaptive imaging; The second determination module is used to rotate the extension direction of the conductor counterclockwise horizontally, simulate and obtain the geographical coordinates of the rotated transmission line, locate the center point of the transmission line scattering spot based on the center point positioning device of the transmission line scattering spot according to any one of claims 9, and use the heading angle when the center point of the transmission line spot is located at the transmission line mounting point as the positive direction limit heading angle of the transmission line scattering spot adaptive imaging; The third determination module is used to simulate and obtain the geographical coordinates of the rotated transmission line when the extension direction of the horizontal rotating conductor is consistent with the flight direction of the radar sensor, locate the center point of the transmission line scattering spot based on the center point positioning device of the transmission line scattering spot according to claim 9, and use the angle when the center point of the transmission line scattering spot is located at the middle position of the mounting points at both ends of the transmission line as the optimal heading angle for the adaptive imaging of the transmission line scattering spot.

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