Method for generating dynamic return flight route of unmanned aerial vehicle of transformer substation

Abstract

The invention discloses a method for generating a dynamic return flight route of a transformer substation unmanned aerial vehicle, and the method comprises the steps: S1, constructing a double-layer safety region based on a voltage level: constructing a safety cuboid region with Pn as a center, the bottom surface of the safety cuboid region being a square with the length of 2r, and the height of the safety cuboid region being hsafety; an inscribed safety cylinder is constructed in the safety cuboid, the radius of the cylinder is r, and the height of the cylinder is hsafety; s2, point cloud double dynamic filtering: selecting a safe return point S; and S3, generating an obstacle avoidance path driven by road inflection points: calculating a shortest path sequence Path = [S, p, p,..., T] from S to a nest T by adopting an A * algorithm, and taking the shortest path sequence as a return waypoint sequence. According to the method, in the process that the unmanned aerial vehicle executes inspection operation, when it is detected that the unmanned aerial vehicle cannot completely execute the route, the waypoint meeting the requirement for rising to the safe return flight height is rapidly determined, so that the safety of the subsequent return flight process is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of UAV power inspection, and specifically to a method for generating a dynamic return flight path of a substation UAV. Background Art

[0002] With the rapid development of UAV technology, its application in the power system is becoming increasingly widespread. Especially in the inspection of substation equipment, UAVs have gradually become important auxiliary tools due to their high efficiency and flexibility. Currently, the inspection of UAVs in substations generally relies on UAVs with RTK high-precision positioning to execute preset flight paths for the inspection of medium and high-level equipment in the station. And the flight path generally sets a safe flight path from the UAV airport to the equipment inspection point to ensure that the UAV can fly at a safe height above the inspection road, thus avoiding the risk of collision with equipment.

[0003] However, in the actual operation process, due to the limited battery life, the problem of the UAV returning with low battery is particularly critical. The traditional UAV return methods mainly rely on simple straight-line return or return along the preset flight path. Although this method is simple to implement, there are significant safety hazards in complex environments such as substations. There are usually a large number of high-precision electrical equipment distributed in substations, and these equipment areas often have strict no-fly requirements. The traditional return methods do not fully consider the terrain and obstacle distribution, and it is easy to cause the return path to cross the equipment area, thus triggering potential collision risks.

[0004] Therefore, how to generate a safe and efficient return flight path in the UAV power inspection operation has become an urgent technical problem in the current substation UAV inspection technology. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, an object of the present invention is to propose a method for generating a dynamic return flight path of a substation UAV. This method can quickly determine a flight point that meets the requirement of rising to a safe return height during the UAV inspection operation when it is detected that the UAV battery power is insufficient to complete the entire flight path, so as to ensure the safety of the subsequent return process.

[0006] To solve the above problems, the present invention provides a method for generating a dynamic return flight path of a substation UAV, including the following steps:

[0007] S1. Construct a double-layer safety area based on voltage levels: In response to the UAV low-battery signal, obtain the current flight point P n with longitude, latitude and altitude coordinates of the substation voltage level, and dynamically determine the safety distance r according to the voltage level; then with P nConstruct a safe cuboid area centered on it. The bottom surface of the safe cuboid area is a square with a length of 2r, and the height of the safe cuboid area is h safe ; Then construct an inscribed safe cylinder within the safe cuboid. The radius of the cylinder is r and the height is h safe ;

[0008] S2. Point cloud double dynamic filtering:

[0009] Extract the point cloud data set G within the safe cuboid pc , when G pc The number of points < 1000, then select P n As the safe return point S;

[0010] When G pc The number of points ≥ 1000, filter the point cloud data set G within the cylinder pc '; When G pc ' The number of points < 1000, then select P n As the safe return point S; Otherwise, iteratively execute steps S1 - S2 bidirectionally along the inspection route;

[0011] S3. Generation of obstacle avoidance path driven by road inflection points:

[0012] Based on the pre - marked set of device no - fly polygons and the set of inspection road inflection points , perform ray - method intersection detection on the connections from the safe return point S obtained in S2 to each , and only retain the line segments that do not intersect any device polygons; Then construct an unweighted graph G' from the retained line segments, and use the algorithm to calculate the shortest path sequence from S to the nest T , as the return flight point sequence.

[0013] Preferably, in S1, when constructing the safe cylinder, the axis of the cylinder coincides with the central axis of the cuboid, and the bottom circle of the cylinder is inscribed in the bottom square of the cuboid.

[0014] Preferably, in S2, when extracting points within the safe cuboid area from the point cloud, it is necessary to calculate the longitude span δlon of r in the east - west direction and the longitude span δlat of r in the north - south direction centered on Pn through the distance conversion coordinate formula;

[0015] ;

[0016] ;

[0017] Where R is the radius of the earth, and filter the points that meet all the following conditions in the point cloud data to form a point set G Pc :

[0018] 。

[0019] Preferably, in S2, when double dynamic filtering of the point cloud is performed, the spherical distance formula needs to be used to calculate the horizontal distance between P n and the point cloud:

[0020] ;

[0021] In the formula: R is the radius of the earth, and the earth is regarded as a standard sphere;

[0022] If L ≤ r, it is considered that the point is located within the safety cylinder;

[0023] Traverse all points in G Pc Put all the points within the safety cylinder into a new point set G Pc ’, if the number of points in G Pc ’ is less than 1000, it is considered that there are no obstacles in this area, meeting the condition for the drone to directly ascend, and use the current waypoint as the safe return point S.

[0024] Preferably, S3 includes the following sub-steps:

[0025] S3.1. Construct a two-dimensional map device area model:

[0026] On the two-dimensional electronic map of the substation, use polygons to mark all key device areas, such as transformers, lightning arresters, circuit breakers, etc.; each polygon is represented by a set of ordered coordinate points, which are used to define the boundary of the safe no-fly zone of the device;

[0027] S3.2. Mark the information of road inflection points:

[0028] Mark all road inflection points in the inspection path within the substation, that is, the key points where the path turns or branches; store them as a point set where ;

[0029] S3.3. Initial path generation:

[0030] Based on the safe return point S of the drone breakpoint selected in Invention Point 1, connect lines from the starting point S to each inflection point in turn to form candidate path segments; for each line segment , judge whether it intersects with any device area polygon; use the ray method or intersection detection algorithm for geometric judgment; if the line segment intersects with any device area, discard the line segment;

[0031] S3.4. Construct a feasible path network and find the shortest path:

[0032] Form a graph G' with all the uneliminated path segments, where the nodes are S and each inflection point, and the edges are the safe path segments; use the Dijkstra algorithm or algorithm to find the shortest path from the starting point S to the drone nest position T in the graph G'; output the sequence of path points as the sequence of return flight waypoints.

[0033] The advantages of the present invention compared with the prior art are as follows:

[0034] (1) By combining the three-dimensional point cloud data in real time during the flight, the present invention constructs a safe ascending cylinder model to accurately identify whether there are obstacles blocking the path, ensuring that the safe return flight waypoints selected by the drone when the battery is low have sufficient vertical safety space. This method not only improves the ability of the drone to cope with emergencies in a complex substation environment but also ensures that the drone can safely return to the drone nest, significantly reducing the risk of equipment damage caused by collisions.

[0035] (2) By marking the equipment area and the inflection points of the inspection road on the two-dimensional map and combining the path intersection detection algorithm, the present invention can dynamically generate the shortest return flight path avoiding high-voltage equipment. This method can not only effectively avoid no-fly zones such as high-voltage equipment but also dynamically adjust the return flight path according to the actual terrain, thus improving the flexibility and adaptability of path planning. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0037] Figure 1 It is a schematic diagram of the ascending safety cuboid and the safety cylinder in the present invention.

[0038] Figure 2 It is a flowchart of the method for selecting safe return flight waypoints for substation drone inspection breakpoints based on point cloud data in the present invention.

[0039] Figure 3 It is a flowchart of the method for dynamically programming a safe return flight route in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The following details the embodiments of the present application. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application.

[0041] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0042] The present invention will be further described in detail below with reference to the accompanying drawings.

[0043] Combined with Figures 1 to 3 , a method for generating a dynamic return flight path of an unmanned aerial vehicle in a substation according to the present invention

[0044] The technical solution for achieving the first object of the present invention is:

[0045] (1) Determine the safety verification range of the return flight path

[0046] When using an unmanned aerial vehicle for inspection in a substation, the safety distance r for substation inspection needs to be followed, and the requirements are as follows:

[0047]

[0048] (2) Establish the safe cuboid area for ascent

[0049] Obtain the coordinates of the current execution waypoint , where h n is used as the bottom height of the safe cuboid, and obtain the safe height h safe for return as the top height of the safe cuboid. The bottom of the cuboid is a square, and it extends a distance r in the four directions of east, west, south, and north with P n as the center to form a square area.

[0050] (3) Extract the points within the safe cuboid area from the point cloud

[0051] Calculate the longitude span δlon when extending a distance r in the east-west direction and the latitude span δlat when extending a distance r in the north-south direction with Pn as the center through the distance conversion coordinate formula.

[0052] ;

[0053] where R is the radius of the earth. Since the calculation range is small, the earth can be approximately regarded as a standard sphere here.

[0054] Filter the points in the point cloud data that meet all the following conditions Form a point set G Pc :

[0055] ;

[0056] If the number of points in G Pc is less than 1000, it is considered that there is no device in this area that can directly ascend. Then the current waypoint can be used as the safe return waypoint S.

[0057] (4) Extract the points in the safe cylinder area from the safe cuboid area

[0058] If the number of points in G Pc exceeds 1000, further screening is required in this area. That is, taking the bottom square area as the bottom surface, construct an inscribed safe cylinder. The specific method is to calculate the horizontal distance L between the coordinates of Pc and Pn.

[0059] ;

[0060] where R is the radius of the earth. Since the calculation range is small, the earth can be approximately regarded as a standard sphere here.

[0061] If L is less than or equal to r, it is considered that the point is located inside the safe cylinder.

[0062] Traverse all the points in G Pc and put all the points inside the safe cylinder into a new point set G Pc '. If the number of points in G Pc ' is less than 1000, it is considered that there is no device in this area that can directly ascend. Then the current waypoint can be used as the safe return waypoint S.

[0063] (5) Repeat until a point that can return safely is found

[0064] If the number of points in G Pc ' is still greater than 1000, then starting from the current route as the center, execute steps (1)-(4) for the upstream and downstream waypoints in turn until a waypoint that can ascend safely is found, which is used as the safe return waypoint. During the return process, first follow the route from the current waypoint to the return waypoint along the route and then ascend to the safe altitude for return.

[0065] If no returnable waypoint is found after looping to the start or end of the route, then execute the previous or subsequent route of the route for return.

[0066] The second object of the present invention is to provide a method for dynamic return flight route planning. By marking the equipment area on the two-dimensional map of the substation, the marking frame is a polygon. Then mark all the inflection points of the roads, that is, the points where the inspection road turns or branches. When the UAV returns due to low battery, starting from the current position of the UAV, connect the road inflection points in sequence, remove the connecting lines that intersect with the equipment area, and then find the connecting line with the shortest path among all the remaining connecting lines as the safe return flight route.

[0067] The technical solution for realizing the second object of the present invention is as follows:

[0068] (1) Construct a two-dimensional map equipment area model

[0069] On the two-dimensional electronic map of the substation, use polygons to mark all key equipment areas, such as transformers, lightning arresters, circuit breakers, etc.; each polygon is represented by a set of ordered coordinate points, which are used to define the boundary of the safe no-fly zone of the equipment. Example: The boundary of equipment A is a quadrilateral, and its vertex coordinates are: .

[0070] (2) Mark the road inflection point information

[0071] Mark all the road inflection points in the inspection path in the substation, that is, the key points where the path turns or branches; store them as a point set , where .

[0072] (3) Initial path generation

[0073] Based on the safe return point S of the UAV break point selected in the first invention point, connect from the starting point S to each inflection point in sequence to form candidate path segments; for each line segment , judge whether it intersects with any equipment area polygon. Use the ray method or intersection detection algorithm for geometric judgment; if the line segment intersects with any equipment area, discard the line segment.

[0074] (4) Construct a feasible path network and find the shortest path

[0075] Combine all the path segments that have not been excluded to form a graph G', where the nodes are S and each inflection point, and the edges are safe path segments; use the Dijkstra algorithm or algorithm to find the shortest path from the starting point S to the nest position T in the graph G'; output the path point sequence , as the return flight waypoint sequence.

[0076] It should be noted that:

[0077] I. The method for obtaining point cloud data in the present invention adopts mature means in the prior art, and preferably includes the following two: 1. At present, most substations have completed the construction of point cloud models, and the completed point cloud data of the substations can be directly used; 2. Through the airborne laser scanning device of the DJI L2 drone, a panoramic three-dimensional point cloud model of the substation is constructed.

[0078] II. In the present invention, the acquisition method of the current point P n latitude-longitude-altitude coordinates adopts mature means in the prior art, where P n is a set of waypoints in the preset flight path, and the waypoint information stores information such as coordinates and altitude, and the latitude-longitude-altitude coordinate information of the current point where the drone is located can also be collected by the positioning unit carried in the existing drone; after positioning P n , then the positions and ranges of the safety cuboid and the safety cylinder are positioned based on P n .

[0079] III. In the present invention, 1000 is defined as the judgment threshold for the number of points of G pc and G pc ', and the reasons are as follows:

[0080] First, during the point cloud acquisition process, noise points will be generated due to impurities such as dust in the environment or equipment accuracy. However, the number of noise points is not large. At the same time, in the point clouds collected by conventional point cloud products such as the DJI L2, the minimum number of points of the transmission and distribution line conductors within the set safety cuboid or cylinder is also tens of thousands. Therefore, setting 1000 points is a reasonable setting that fully considers the characteristics of the point cloud and the actual situation while combining experience.

[0081] Finally, the unmentioned parts of the present invention all adopt mature products and mature technical means in the prior art.

[0082] The above describes the present invention and its implementation manners. This description is not restrictive, and what is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and design similar structural manners and embodiments without creative work without departing from the gist of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A method for generating a dynamic return flight route of an unmanned aerial vehicle in a substation, characterized in that Including the following steps: S1. Construct a two-layer security area based on voltage levels: In response to the low battery signal of the drone, obtain the current waypoint P n Latitude, longitude and altitude coordinates of the substation voltage level, and dynamically determine the safety distance r according to the voltage level; then construct a safety cuboid area with P n as the center. The bottom surface of the safety cuboid area is a square with a length of 2r, and the height of the safety cuboid area is h safe ; then construct an inscribed safety cylinder within the safety cuboid. The radius of the cylinder is r and the height is h safe ; S2. Dual dynamic filtering of point cloud: Extract the point cloud data set G within the safe rectangle pc , when G pc The number of points < 1000, then select P n as the safe return point S; When G pc The number of points ≥ 1000, filter the point cloud data set G within the cylinder pc '; When G pc ' The number of points < 1000, then select P n as the safe return point S; Otherwise, iteratively execute steps S1 - S2 bidirectionally along the inspection route; S3. Generation of obstacle avoidance path driven by road inflection points: Pre - marked set of device no - fly polygons and set of inflection points of patrol roads , perform ray - method intersection detection on the lines connecting the safe return point S obtained in S2 to each , and only retain the line segments that do not intersect any device polygon; Then, construct the reserved line segments into an unweighted graph G', and use the algorithm to calculate the shortest path sequence from S to the nest T , which is used as the return flight waypoint sequence.

2. The method for generating a dynamic return flight route of an unmanned aerial vehicle for a substation according to claim 1, wherein: In the above S1, when constructing the safety cylinder, the axis of the cylinder coincides with the central axis of the cuboid, and the bottom circle of the cylinder is inscribed in the bottom square of the cuboid.

3. A method for generating a dynamic return flight route of an unmanned aerial vehicle in a substation according to claim 1, characterized in that: In S2, when extracting points within the safe cuboid region from the point cloud, the longitude span δlon of r in the east-west direction and the longitude span δlat of r in the north-south direction centered at P need to be calculated through the distance conversion coordinate formula; n ​ ； ； where R is the radius of the earth, and points that meet all of the following conditions are selected from the point cloud data to form a point set G Pc : 。 4. A method for generating a dynamic return flight path of an unmanned aerial vehicle at a substation according to claim 3, characterized in that: In S2, when performing double dynamic filtering on the point cloud, the spherical distance formula needs to be used to calculate the horizontal distance between P n and the point cloud: ； In the formula: R is the radius of the earth, considering the earth as a standard sphere; If L ≤ r, it is considered that the point is located inside the safety cylinder; Traverse all points in G Pc and put all points within the safety cylinder into a new point set G Pc '. If the number of points in G Pc ' is less than 1000, it is considered that there is no obstacle in this area, meeting the condition for the drone to directly ascend, and the current waypoint is used as the safe return point S.

5. A method for generating a dynamic return flight route of an unmanned aerial vehicle in a substation according to claim 3, characterized in that: The above S3 includes the following sub - steps: S3.

1. Construction of a two - dimensional map of the equipment area model: On the two - dimensional electronic map of the substation, use polygons to mark all key equipment areas, such as transformers, lightning arresters, circuit breakers, etc.; each polygon is represented by a set of ordered coordinate points, which are used to define the boundary of the safety no - fly zone of the equipment; S3.

2. Marking of road inflection point information: Mark all the road turning points in the inspection path within the substation, that is, the key points where the path turns or branches; store them as a set of points , where ; S3.

3. Initial path generation: Based on the selected UAV breakpoint safe return point S in Invention Point 1, connect from the starting point S to each inflection point in sequence to form candidate path segments; for each line segment , determine whether it intersects with any device area polygon; Use the ray method or cross - detection algorithm for geometric judgment; if the line segment intersects any equipment area, discard the line segment; S3.

4. Construction of a feasible path network and finding the shortest path: Form a graph G' with all the path segments that have not been eliminated, where the nodes are S and each inflection point, and the edges are the safe path segments; use the Dijkstra algorithm or algorithm to find the shortest path from the starting point S to the drone nest location T in the graph G'; output the sequence of path points , which serves as the sequence of waypoints for the return flight.

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