Transport aircraft waypoint extraction and ordering method and multi-target air drop trajectory planning method

Abstract

The application discloses a transport aircraft waypoint extraction and sequencing method and a multi-target air drop trajectory planning method. The transport aircraft waypoint extraction and sequencing method comprises the following steps: acquiring all ground target points and feasible air drop circular domains of the ground target points; extracting air drop waypoints on the basis of the feasible air drop circular domains of the ground target points based on a greedy strategy; and performing optimal sequencing and trajectory planning on the air drop waypoints. The application relates to the technical field of trajectory planning, and can realize integrated planning from terrain-driven landing area selection to transport aircraft path planning to multi-wing parachute coordinated trajectory optimization for large-scale air drop tasks, thereby providing a general solution for air drop and homing of a wing parachute system in a complex environment, avoiding the uncoordinated problems caused by independent planning of each part in a traditional method, and enhancing the systematicness and planning efficiency of a task.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of trajectory planning, in particular to a transport aircraft waypoint extraction and sorting method and a multi-target air-drop trajectory planning method. BACKGROUND

[0002] Wing-sail systems are widely used in disaster relief and civilian air-drop missions. However, when performing tasks in non-cooperative areas, the uncertainty of the terrain and communication restrictions often lead to loss of supplies and task failure, which makes the selection of safe landing sites crucial. In recent years, advances in navigation, guidance and control (GNC) technology have enabled wing-sail systems to achieve precise homing, especially in areas where ground transportation is limited, making the application of this technology particularly valuable.

[0003] The complexity of large-scale air-drop missions lies in the strong coupling relationship between landing area terrain perception, transport aircraft flight path planning and multi-target wing-sail deployment. After determining the landing site, the problem can be decoupled into a two-level optimization framework: the upper level is a combination optimization problem of transport aircraft path, and the lower level is a continuous control problem of wing-sail system. The upper-level problem is essentially a constrained traveling salesman problem (TSP) that requires solving the optimal flight path of the transport aircraft covering all drop zones under the premise of safety; the lower-level problem constructs a multi-objective optimal control problem for wing-sail trajectory for each pre-set drop point to solve the coordinates of the optimal air-drop drop point and the homing control law of each system.

[0004] Existing research methods mostly solve each sub-problem independently, i.e., aircraft flight path planning based on simplified dynamic models (ignoring wing-sail system characteristics) or homing trajectory optimization for pre-set drop points. These methods, while solving air-drop problems in specific scenarios, are difficult to achieve multi-target collaborative optimization in complex task environments, thus limiting the robustness and adaptability of the overall scheme. SUMMARY

[0005] To overcome the deficiencies in the prior art, the present application provides a transport aircraft waypoint extraction and sorting method and a multi-target air-drop trajectory planning method for large-scale air-drop missions, which realizes integrated planning from terrain-driven landing area selection, transport aircraft path planning to multi-wing-sail collaborative trajectory optimization, and provides a general solution for wing-sail system air-drop and homing in complex environments.

[0006] To achieve the above purpose, the present application provides a transport aircraft waypoint extraction and sorting method, comprising the following steps:

[0007] Step 101, obtaining all ground target points and the feasible air-drop circular domains of each ground target point;

[0008] Step 102, based on the feasible air-drop circular domains of each ground target point, extracting air-drop waypoints based on a greedy strategy;

[0009] Step 103, optimal sorting and trajectory planning are performed on each of the airdrop waypoints.

[0010] To achieve the above object, the application further provides a multi-target airdrop trajectory planning method, comprising the following steps:

[0011] Step 201, terrain analysis is performed on the pre-landing area, a safe landing target point is selected, and a plurality of ground target points to be detected are obtained;

[0012] Step 202, the above method is used to extract and sort the transport aircraft waypoints, to obtain a plurality of non-intersecting airdrop areas and path points;

[0013] Step 203, based on the airdrop areas and path points obtained in step 202, single-drop-point multi-target-point airdrop task planning or single-drop-point single-target-point airdrop task planning is performed.

[0014] Compared with the prior art, the application has the following beneficial technical effects:

[0015] The application significantly improves the reliability, adaptability and robustness of the wing parachute system in large-scale airdrop tasks by realizing integrated planning of landing area selection, transport aircraft route planning and multi-target airdrop task optimization. At the task planning level, the application combines landing area selection and transport aircraft route planning, dynamically adjusts the flight path and drop point of the transport aircraft according to real-time terrain information, thereby ensuring that the wing parachute can land safely in a complex environment. This integrated method effectively avoids the coordination problems caused by independent planning of each part in the traditional method, and enhances the systematicness and planning efficiency of the task.

[0016] In addition, when facing sudden uncertainties, the framework proposed by the application can still quickly adjust and optimize the strategy, re-plan the transport aircraft route and the wing parachute homing trajectory, thereby ensuring the smooth progress of the task. Through this integrated planning method, the application provides an efficient and reliable solution for large-scale wing parachute airdrop tasks, and has important practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from the structures shown in these drawings without creative labor.

[0018] Figure 1 Flow chart of the transport aircraft waypoint extraction and sorting method in the embodiments of the application;

[0019] Figure 2 Flow chart of the multi-target air drop trajectory planning method in the embodiment of the present application;

[0020] Figure 3 Schematic diagram of the terrain analysis simulation result in the embodiment of the present application;

[0021] Figure 4 Schematic diagram of the feature point distribution in the embodiment of the present application;

[0022] Figure 5 Schematic diagram of the intersection of feasible regions in the embodiment of the present application;

[0023] Figure 6 Schematic diagram of the air drop feasible region set in the embodiment of the present application;

[0024] Figure 7 Two-dimensional schematic diagram of the optimal air drop release point (CARP) in the embodiment of the present application;

[0025] Figure 8 Control curve diagram of the three homing tracks in the embodiment of the present application.

[0026] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0029] In addition, the description such as “first”, “second” and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first”, “second” can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of “multiple” is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0030] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixing", and the like should be understood broadly, for example, "fixing" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection, or physical connection, or wireless communication connection; can be directly connected, or indirectly connected through intermediate medium, can be internal communication of two elements or interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] In addition, the technical solutions among various embodiments of the present application can be combined with each other, but it must be based on that the combination of technical solutions can be realized by those skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.

[0032] The embodiment discloses a transport aircraft waypoint extraction and sorting method for large-scale air drop task and a multi-target air drop trajectory planning method, which can realize integrated planning from terrain-driven landing area selection, transport aircraft path planning to multi-wing parachute coordinated trajectory optimization, and provides a general solution for air drop and homing of wing parachute system in complex environment.

[0033] Reference Figure 1 The transport aircraft waypoint extraction and sorting method in the embodiment mainly includes the following steps:

[0034] Step 101, obtaining all ground target points and feasible air drop circular domains of each ground target point, the feasible air drop circular domain is calculated according to the coordinates of the ground target point and the air drop domain radius parameter;

[0035] Step 102, based on the feasible air drop circular domain of each ground target point, extracting air drop waypoints based on the greedy strategy;

[0036] Step 103, optimal sorting and trajectory planning of each air drop waypoint.

[0037] After acquiring multiple ground target points to be detected, these ground target points represent ground landing positions, not transport aircraft waypoints. When performing a multi-target airdrop mission, the transport aircraft must fly over the airspace area above the target points in order to successfully carry out the airdrop mission. The feasible airdrop circular area corresponding to each point is calculated from the set of ground target points. When the feasible airdrop areas of adjacent targets overlap, a single-flight multi-target airdrop scheme can be adopted, namely the technical solution disclosed in the prior art CN115079724B. For cases where the feasible areas of targets partially overlap and some spatial distributions are discrete, it is necessary to sort the waypoints and plan the trajectory of the transport aircraft in the airdrop mission, which includes two steps: (1) airdrop waypoint extraction based on a greedy algorithm, i.e., step 102 above; (2) optimal sorting of waypoints and trajectory planning based on the traveling salesman problem, i.e., step 103 above.

[0038] In the specific implementation of step 102, the intersection relationship of feasible airdrop circles corresponding to all ground target points is first obtained. It is important to note that for any target point, its airdrop point can be planned within the intersection of feasible regions or at any location within its own independent circle. Therefore, the number of airdrop point clusters corresponding to the target point set and their coordinates are unknown, leading to the scheduling decision problem: how to plan airdrop points for each target point. Based on this, this embodiment proposes a clustering method based on a greedy strategy. By grouping airdrop regions, it maximizes the coverage of multiple target areas in a single airdrop while ensuring the feasibility of subsequent return path planning.

[0039] The specific implementation process of the greedy strategy for extracting airdrop waypoints in this embodiment includes the following steps:

[0040] Step 102.1, Create A uniform grid cover can encompass the rectangular boundary region of all feasible drop circles, and the union of all feasible drop circles is denoted as the set of remaining circles. Initialize the feasible airdrop zone result set Empty;

[0041] Step 102.2: Create a binary mask matrix for each feasible airdrop circle, assigning a value of 1 to the grid inside the circle and 0 to the grid outside the circle; superimpose the binary mask matrices of all feasible airdrop circles to record the number of times each grid in the uniform grid is covered by a feasible airdrop circle, and then... OK The number of overlaps of the grid of a column covered by a feasible drop circle is denoted as . ;

[0042] Step 102.3: Identify the current maximum overlap. ,Right now :

[0043] like The current set of remaining circles All isolated feasible airdrop circles are stored in the feasible airdrop area result set. Then, repeat step 102.3 to continue the loop;

[0044] like Output the set of currently feasible airdrop zones. The loop terminates.

[0045] like Extract the intersection region of the feasible airdrop circles corresponding to the current highest-order overlap number, and store the intersection region into the feasible airdrop area result set. Then, the feasible airdrop circle corresponding to the intersection region is removed from the remaining circle set. After removing it from the middle, repeat step 102.3 to continue the loop;

[0046] Step 102.4: Extract the feasible airdrop zone result set. All disconnected regions' endpoints , Obtain the point set of waypoints , ,in, Results set for feasible airdrop zones The number of disconnected regions in the middle. , These are the results sets for feasible airdrop zones. The Middle The earliest and latest feasible deployment points for each region.

[0047] Assuming feasible airdrop zone result set There is There are three disconnected regions, and the endpoints of each region are denoted as . and , The subscript "e" indicates the earliest feasible drop point, and "l" indicates the latest feasible drop point. Endpoint selection satisfies the criterion of maximizing the length of the intercepted line segment within the domain, ensuring the delivery aircraft has sufficient time margin to execute the airdrop mission. The following section uses the [missing information - likely a specific example or term] as an example. Taking a disconnected region as an example, the point set Constraints to be satisfied:

[0048] ;

[0049] in, For the region endpoint , distance, For the region endpoint coordinates For the region endpoint coordinates Here is the envelope of the feasible airdrop region at altitude H. , for The determined flight path equation parameters, Indicates the flight path and intersection , coordinate.

[0050] During the implementation of step 103, the set of points connecting waypoints In This generates a set of discrete path segments, forming the planned path for the transport aircraft. This embodiment transforms the transport aircraft's flight path planning problem into an open-loop Traveling Salesman Problem (TSP), that is, designing the shortest path to sequentially connect these path segments, ultimately determining the transport aircraft's flight trajectory. To balance algorithm accuracy and efficiency, this embodiment designs a dynamic programming method that switches the optimization solver based on parameter size, specifically:

[0051] Calculate the values ​​of each disconnected subregion by Determined line segment length ;

[0052] Calculate the distances between the endpoints of different line segments;

[0053] Adaptive path selection optimization methods include:

[0054] like It employs exact tree search, i.e., exhaustive permutation. The path planning method is used to select the shortest total path as the planned path for the transport aircraft.

[0055] like The algorithm employs a nearest neighbor heuristic and a greedy strategy, selecting the minimum increment at each step to obtain the planned route for the transport aircraft, thus reducing the computational complexity to [value missing]. The scale, and its specific implementation process are as follows:

[0056] Step 103.1: Randomly select a line segment as the initial path and determine the initial direction of the connecting points, i.e., from... arrive Or from arrive One of the two directional options is randomly selected;

[0057] Step 103.2, determine if there are any unvisited line segments:

[0058] If yes, the nearest end point of the current path end point is selected from all end points in all unvisited line segments, and the end point direction that minimizes the connection distance is selected, the selected segment corresponding to the nearest end point is added to the current path, and then the line segment of the current added path is marked as visited, and step 103.2 is performed again.

[0059] Otherwise, the current path is taken as the transport machine planning path, and output.

[0060] Reference Figure 2 The multi-target air drop trajectory planning method in the embodiment mainly includes the following steps:

[0061] Step 201, terrain analysis is performed on the pre-landing area, a safe landing target point is selected, and a plurality of ground target points to be detected are obtained;

[0062] Step 202, the transport aircraft waypoint extraction and sorting method described above is used to extract and sort the transport aircraft waypoints, to obtain a plurality of non-intersecting air drop regions and path points;

[0063] Step 203, based on the air drop regions and path points obtained in step 202, single-drop-point multi-target-point air drop task planning or single-drop-point single-target-point air drop task planning is performed.

[0064] In the specific implementation process of step 201, the terrain of the pre-landing area is analyzed to select a safe landing ground target point. Specifically, the terrain of the pre-defined landing area is analyzed using a digital elevation model (DEM) to determine a nominal landing point that meets the terrain parameters suitable for parachute landing. Secondly, since the number of nominal landing points is large, it is not practical to drop to all landing points, and it is necessary to select a plurality of feature points from the nominal landing points as ground target points for the air drop task. The principle of selecting the feature points is to cover all nominal landing points with a circle centered at the feature point while reducing the number of feature points as much as possible, and the selection of the feature radius is based on the air drop feasible domain radius of the current air drop task. The specific implementation of terrain analysis and feature point selection refers to the prior art CN119225422A, and will not be described here.

[0065] After obtaining a plurality of non-intersecting air drop regions, path points, and corresponding target points, the multi-target air drop trajectory planning problem is converted into a single-drop-point multi-target-point or single-drop-point single-target-point air drop task planning problem. The single-drop-point multi-target-point air drop task planning problem needs to solve two sub-problems: one is to find the CARP coordinates of multiple targets on the path point line segment in a single air drop region , and the other is to design a plurality of homing trajectory control laws corresponding to different target points. The decomposition idea of the single-drop-point single-target-point air drop task planning problem is similar, but only needs to solve the CARP coordinates of a target point on the path point line segment in a single circle domain Redesign a set of homing trajectory control laws corresponding to the target point. Convert the problem into a multi-constraint initial value optimization problem, whose task is to find the optimal air-drop release point CARP that satisfies the constraints given the target point Optimal path planning. The air-drop task planning problem with a single release point and multiple target points uses optimal control theory and computational geometry principles to solve the air-drop feasible region. For details, refer to the prior art CN115079724B. The solution to the air-drop task planning problem with a single release point and a single target point requires solving an optimal control problem with terminal constraints. The problem is described as follows:

[0066] ;

[0067] wherein, is the performance index, is the first performance index component, is the second performance index component, is the trajectory terminal point coordinate, i.e., the CARP ; is the coordinate of the region endpoint , is the control variable, is the weight coefficient, which determines the preference of the performance index; is the set of differential equations satisfied by the wing-sail system, is the approach speed direction of the carrier, a , b is the determined fly-in route equation parameter, θ 1, θ 2 is the range of the angle between the carrier fly-in direction and the positive direction of the OX axis in the plane, is the air-drop feasible region envelope at H height.

[0068] The transport aircraft waypoint extraction and sorting method and the multi-target air-drop trajectory planning method in this embodiment will be further described in conjunction with a specific simulation example.

[0069] In response to the demand for large-scale air-drop tasks, a DEM map with a resolution of 25 meters and a size of 22200m x 22200m is selected for simulation, which covers a specific latitude and longitude range from (28.14°N, 113.22°E) to (28.34°N, 113.42°E). According to the terrain analysis, the selected flat points, safe landing points, reliable obstacle avoidance points, and nominal landing points in the specified area are as shown in Figure 3 It can be seen that the range of landing points in the area is gradually reduced, and finally reduced to the point where the black point is located in the figure, which is the working point suitable for wing-sail landing task with terrain undulation, i.e., the nominal landing point.

[0070] After getting the nominal landing point, several feature points are selected as the target points of the airdrop mission according to the pre-set feature point selection principle. The feature points distribution is shown in Figure 4 Figure 4 The feature points are represented by red dots and the feature circle with a radius of 4000m is centered at the feature points. Meanwhile, the specific locations of the feature points are shown in Table 1.

[0071] Table 1 Specific locations of feature points

[0072]

[0073] Using the feature points in Table 1 (the nominal radius is 4668m), the feasible region and its corresponding endpoints are obtained by applying the greedy clustering algorithm, and the results are shown in Figure 5 and Figure 6 By observing the superposition of each circle region in Figure 5 , it can be seen that the feasible airdrop region is composed of 5 unconnected regions. Among them, the maximum overlap degree is 4 (region 3 in Figure 6 ), and a single drop point (CARP) in this region simultaneously drops 4 wing parachutes for homing.

[0074] In Figure 6 , the endpoints of the longest line segment in each unconnected region are marked with orange circles. Then, a tree search algorithm is used to plan a shortest tour path that connects these line segments in sequence. The region sequence obtained is 5-2-1-3-4, and the total path length is 75563.5m, which is the path planning result of the transport aircraft.

[0075] Based on the selected 9 target landing points and the calculated transport aircraft route, the multi-objective optimal control problem on each delivery path is solved using the interior point method. The simulation uses piecewise constant control, and the number of segments for each trajectory is 10. The drop height H is 2000m. The wind speed is 1.414m / s, which is at an angle of 45° with the Ox axis. The simulation parameters of the wing parachute system are shown in Table 2.

[0076] Table 2 Simulation parameters of wing parachute system

[0077]

[0078] The homing trajectories of the wing parachute system to each target point are shown in Figure 7 . It can be seen that as the transport aircraft passes through the feasible region of each target point in sequence along the delivery route, the wing parachutes are dropped at each optimal drop point and controlled to land at the target point respectively against the wind. Figure 8 The control law of the three trajectories released from the airdrop point 3 shown in Figure 7 is shown.

[0079] ​Table 3 shows the optimal release point coordinates and corresponding planning time. It is noted that due to computational difficulty, one target point was re-planned, and the number of wingsuits for region 3 was changed from 4 to 3. The release path for this target point corresponds to line segment 1 listed in Table 3. In terms of computation time, as the number of target points increases, the planning time also increases. This is because the more target points there are, the more constraints the optimal control problem needs to satisfy, and the more difficult the problem is to solve.

[0080] Table 3 CARP optimization results

[0081]

[0082] The above merely describes the preferred embodiments of the present application, and is not intended to limit the protection scope of the present application. Any equivalent structural transformation made according to the present application specification and drawings, or direct / indirect application in other related technical fields, are included in the protection scope of the present application.

Claims

1. A method for extracting and sorting waypoints for transport aircraft, characterized in that, Includes the following steps: Step 101: Obtain all ground target points and the feasible airdrop area for each ground target point; Step 102: Based on the feasible airdrop circle of each ground target point, extract waypoints using a greedy strategy, specifically including: Step 102.1, Create A uniform grid cover can encompass the rectangular boundary region of all feasible drop circles, and the union of all feasible drop circles is denoted as the set of remaining circles. Initialize the feasible airdrop zone result set Empty; Step 102.2: Record the number of times each grid in the uniform grid is covered by a feasible airdrop circular region, and then... OK The number of overlaps of the grid of a column covered by a feasible drop circle is denoted as . ; Step 102.3: Identify the current maximum overlap. ,Right now : like The current set of remaining circles All isolated feasible airdrop circles are stored in the feasible airdrop area result set. Then, proceed to step 102.3 again; like Output the current set of feasible airdrop zones. ; like Extract the intersection region of the feasible airdrop circles corresponding to the current maximum overlap number, and store the intersection region into the feasible airdrop area result set. Then, the feasible airdrop circle corresponding to the intersection region is removed from the remaining circle set. After removing it from the middle, proceed to step 102.3 again; Step 102.4: Extract the feasible airdrop zone result set. All disconnected regions' endpoints , Obtain the point set of waypoints , ,in, Results set for feasible airdrop zones The number of disconnected regions in the middle. , These are the results sets of the feasible airdrop areas. The Middle The earliest and latest feasible deployment points for each region; Step 103 involves optimally sorting and planning the trajectory for each waypoint, specifically including: like It employs exact tree search, i.e., exhaustive permutation. The path planning method is used to select the shortest total path as the planned path for the transport aircraft. like The nearest neighbor heuristic algorithm, based on a greedy strategy, selects the minimum increment at each step to obtain the planned path for the transport aircraft. The process is as follows: Step 103.1: Randomly select a line segment as the initial path and determine the initial direction of the connecting points, i.e., from... arrive Or from arrive One of the two directional options is randomly selected; Step 103.2, determine if there are any unvisited line segments: If so, select the nearest endpoint of the current path endpoint from all endpoints of all unvisited line segments, and select the endpoint direction that minimizes the connection distance. Add the segment corresponding to the nearest endpoint to the current path, and then mark the line segment currently added to the path as visited before proceeding to step 103.2 again. Otherwise, the current path is used as the planned path for the transport aircraft and output.

2. The method for extracting and sorting waypoints for transport aircraft according to claim 1, characterized in that, In step 102.4, the region endpoint , The following constraints must be met: in, For the region endpoint , distance, For the region endpoint coordinates For the region endpoint coordinates Here is the envelope of the feasible airdrop region at altitude H. , for The determined flight path equation parameters, Indicates the flight path and intersection , coordinate.

3. A multi-target airdrop trajectory planning method, characterized in that, Includes the following steps: Step 201: Perform terrain analysis on the pre-landing area, select a safe landing target point, and acquire multiple ground target points to be detected; Step 202: The transport aircraft waypoint extraction and sorting method described in any one of claims 1 to 2 is used to extract and sort the transport aircraft waypoints to obtain several non-intersecting airdrop areas and path points; Step 203: Based on the airdrop area and path points obtained in step 202, perform single-drop-point multi-target-point airdrop mission planning or single-drop-point single-target-point airdrop mission planning.

4. The multi-target airdrop trajectory planning method according to claim 3, characterized in that, In step 203, the single-drop-point, single-target-point airdrop mission planning is transformed into a terminal-constrained optimal control problem, namely: in, For performance indicators, As the first performance index component, As the second performance index component, The coordinates of the trajectory's endpoint. For the region endpoint coordinates To control the quantity, These are the weighting coefficients. Let be the set of dynamic differential equations satisfied by the parachute system. This refers to the direction of the approach velocity of the carrier aircraft. a , b for The determined flight path equation parameters, θ 1. θ 2 represents the range of angles between the direction of the carrier aircraft's flight and the positive direction of the OX axis in the plane. Let H be the envelope of the feasible airdrop region.

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