A route rapid generation method based on vector electronic chart

Abstract

The application designs a route fast generation method based on vector electronic sea chart, comprising the following steps: 1, obtaining task sea area position according to navigation task, and obtaining all electronic sea charts related to the sea area; 2, extracting navigation-obstructing objects contained in each electronic sea chart; 3, performing overlapping extraction, performing intersection operation on the topological intersection of the navigation-obstructing objects, retaining the navigation-obstructing object data of a single sea chart for the non-overlapping area, and saving the navigation-obstructing object data in vector data format; 4, performing buffer processing on the navigation-obstructing objects; 5, performing hierarchical simplification on the navigation-obstructing areas after the buffer processing; 6, inputting the start point and end point positions, first obtaining the collection of the second-level simplified navigation-obstructing areas, judging whether the start point and end point are located in the navigation-obstructing areas, if yes, jumping to step 7, otherwise jumping to step 8; 7, obtaining the first-level simplified navigation-obstructing area as the obstacle environment of the current task area, and then jumping to step 9; 8, jumping to step 9 to find the optimal path, if no reachable path is found, jumping to step 7; 9, finding a shortest route from the start point to the end point by using the binary tree method. The method can realize fast and accurate generation of the route.

Description

Technical Field

[0001] This invention belongs to the field of shipbuilding and navigation technology, and specifically relates to a method for rapid route generation based on vector electronic nautical charts. Background Technology

[0002] Route planning is a key technology for autonomous navigation of intelligent ships. It requires utilizing data from vector electronic charts and other external environmental inputs to model navigable and non-navigable areas in the environment. Based on the start and end points of the mission input, a safe route is planned to circumvent navigational obstructions. Analyzing the navigation missions of intelligent ships and evaluating route quality involves considering factors such as track length, energy consumption, track safety, and smoothness. Multiple constraints must also be considered, including the ship's kinematic characteristics, mission constraints, and planning area constraints. To promptly initiate or switch navigation missions, a superior global route needs to be quickly planned, taking into account various optimization objectives and constraints to improve the mission execution efficiency and navigation safety of intelligent ships.

[0003] Route planning consists of two steps: environmental modeling and path optimization. Environmental modeling constructs an environmental map model based on electronic chart data and other sensor information, while path optimization searches for the optimal path within the constructed environmental space. Environmental modeling, based on different characteristics, is divided into grid-based methods and topology methods, among others. * As a commonly used heuristic search algorithm, the algorithm is based on a gridded environment model. It calculates the cost of each possible path point in the current operating state and then adds the path node with the lowest cost to the search space. However, this algorithm has drawbacks such as long optimization time and uneven path smoothness. Planning a smooth route can reduce the frequency of steering and turning during navigation, effectively improving the ship's navigation stability. Considering the need for navigational autonomy for intelligent ships, quickly generating an executable smooth route under given mission area constraints is fundamental to safe navigation and mission execution. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for rapid route generation based on vector electronic nautical charts.

[0005] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0006] A method for rapid route generation based on vector electronic nautical charts includes the following steps:

[0007] Step 1: Obtain the location of the mission sea area based on the navigation mission, and obtain all relevant electronic nautical charts for that sea area;

[0008] Step 2: Based on the definitions in the electronic chart data dictionary, extract the navigational obstructions contained in each electronic chart, including point-shaped, line-shaped, and area-shaped navigational obstructions;

[0009] Step 3: Determine the overlap range of multiple nautical charts, extract navigational obstructions from different nautical charts within the overlap range, determine whether there is topological intersection of navigational obstructions, if so, perform a merge operation, for non-overlapping areas, retain the navigational obstruction data of a single nautical chart, and save all navigational obstruction data in vector data format.

[0010] Step 4: Buffering obstacles, including: expanding point-shaped obstacles in the obstacle data saved in Step 3 into square obstacles, expanding line-shaped obstacles into polygonal obstacles by translation and extension, and expanding planar obstacles using the angle bisector method, based on the safe distance reserved for the obstacles.

[0011] Step 5: Perform hierarchical simplification on the buffered obstruction areas. Level I simplification uses the sliding window area method to delete redundant vertices of the obstruction areas while retaining the original concave and convex characteristics. Level II simplification involves finding the convex hull of the obstruction area polygon and saving all obstruction area data from the hierarchical simplification.

[0012] Step 6: Input the starting and ending points of the route to be generated. First, obtain the set of Level II simplified obstruction zones. Determine whether the starting and ending points are located within the obstruction zones. If the starting or ending points are located within the obstruction zones, proceed to Step 7; otherwise, proceed to Step 8.

[0013] Step 7: Obtain the Level I simplified obstacle zone as the obstacle environment of the current mission area, and then proceed to step 9;

[0014] Step 8: If neither the starting point nor the ending point is located within a Class II navigation obstruction zone, proceed to step 9 to find the optimal path. If no reachable path can be found, proceed to step 7.

[0015] Step 9: Based on the environmental space within the current task area, establish a route binary tree, find the obstruction zone closest to the starting point, detour from the left and right sides, generate left and right subtrees in a loop, and after constructing the global binary tree, find the shortest route from the starting point to the destination.

[0016] Moreover, the specific method of step 1 is as follows:

[0017] Based on the navigation mission, obtain the vertex position of the mission sea area, obtain the description data of the chart sheet in the electronic chart metadata, obtain the four boundary points of the electronic chart sheet, and generate a rectangular polygon using these four points. Determine whether the rectangular polygon intersects the mission sea area topologically, thereby obtaining all electronic charts that intersect the mission sea area topologically.

[0018] Furthermore, in step 4, the safe distance reserved for the obstacle is:

[0019]

[0020] Where r is the ship's turning radius, e is the positioning error, b is the ship's width, and D0 is the margin.

[0021] Furthermore, the specific steps of step 4 include:

[0022] Step 4.1 The specific method for expanding a linear obstruction into a polygonal obstruction area by translation and extension is as follows: extend the starting point and ending point of the linear obstruction by a reserved safety distance, and then translate it to both sides along the perpendicular direction of the line connecting the starting point and ending point of the linear obstruction. The polygon formed by the two lines after translation is the polygonal obstruction area formed by expanding the linear obstruction.

[0023] Step 4.2: Expand the planar obstruction zone outward to extend the reserved safety distance, and maintain the overall concave-convex characteristics of the original obstruction zone during the expansion process.

[0024] Furthermore, the specific steps of the sliding window area method in step 5 include:

[0025] Step 5.1: Use the sliding window area method to simplify the navigation obstruction area with a large number of vertices. Based on the principle that half of the vector cross product is the directed area of ​​the triangle formed by two vectors, the necessary vertices of the navigation obstruction area are selected by calculating the cumulative directed area value.

[0026] Step 5.2: Starting from the initial vertex of the obstruction zone, take three consecutive vertices in sequence and calculate the directed area of ​​the vector triangle formed by the current three vertices;

[0027] Step 5.3: Compare the calculated area value with the set threshold. If it is greater than the set threshold, the middle vertex is determined to be a necessary vertex and saved. The sliding window is moved one position to the right and the calculated area is cleared to zero. If it is not greater than the set threshold, the middle vertex is determined to be a non-necessary vertex and deleted. The last two vertices are moved one position to the right in turn. The first vertex remains unchanged. The calculated area value is accumulated until the accumulated area value is greater than the set threshold. The sliding window of the three vertices is moved to the right.

[0028] Step 5.4: Repeat the operation in Step 5.3 above until all vertices of the obstruction zone have been traversed;

[0029] Step 5.5: Retain all necessary vertices in the obstruction zone and delete the remaining redundant vertices to obtain the Level I simplified obstruction zone polygon.

[0030] Furthermore, the specific steps of step 9 include:

[0031] Step 9.1: Find the obstruction zone closest to the starting point, detour from the left and right sides, and check whether it exceeds the task area and causes the current path to be blocked, thereby constructing left and right subtrees with boundary constraints;

[0032] Step 9.2: After the global binary tree is constructed, access the cumulative length value of all feasible paths, select the shortest path, find the node index corresponding to the end point of the path, and trace back layer by layer upwards through the parent node index until the starting point is reached, thereby generating the shortest route from the starting point to the end point.

[0033] Advantages and beneficial effects of the present invention:

[0034] 1. In step 5, this invention uses a hierarchical simplification method to model the environment, obtaining Level I and Level II simplification results with different complexities. In steps 6-9, the shortest path is first found based on the Level II simplification result. If the origin and destination are unreachable or there is no reachable path, the search for the shortest path is switched to the Level I simplification result. The hierarchical simplification method can retain polygons of different complexities in the navigation area. In the Level II simplified obstacle environment, it greatly reduces the amount of calculation for detouring in the navigation area, thereby significantly improving the route generation efficiency. It can solve the problem of rapid route generation in various situations where the mission sea area has a large navigable area, large obstacle spacing, few obstacles and high density.

[0035] 2. In step 5, level I simplification, this invention uses the sliding window area method to simplify the obstruction area and delete redundant vertices. Since the vector data of obstructions directly extracted from the nautical chart has complex outlines and many vertices, it will bring a complex amount of calculation to the subsequent path optimization. The simplification process of this invention can retain the shape features of the original obstructions and improve the efficiency of path optimization after level I simplification. It can solve the problem of rapid route generation in complex task sea areas with dense obstacles and small spacing.

[0036] 3. This invention models the environment within the mission area in advance, simplifies and expands obstacles, and checks whether the path is blocked due to exceeding the mission area when circling around the obstruction area from the left and right sides in step 9. A binary tree with the boundary of the mission area is constructed to quickly generate the shortest route considering the constraints of the planning area. Attached Figure Description

[0037] Figure 1 This is a flowchart of the method for rapid route generation according to the present invention;

[0038] Figure 2 A simplified diagram illustrating the hierarchical processing of navigational obstructions. Detailed Implementation

[0039] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.

[0040] A method for rapid route generation based on vector electronic nautical charts, such as Figure 1 and Figure 2 As shown, its inventive point includes the following specific steps:

[0041] Step 1: Obtain the location of the mission sea area based on the navigation mission, and obtain all relevant electronic nautical charts for that sea area;

[0042] The specific method for step 1 is as follows:

[0043] Based on the navigation mission, obtain the vertex positions R1R2R3R4 of the mission sea area, retrieve the descriptive data of the chart sheet from the electronic chart metadata, and obtain the four boundary points A of the electronic chart sheet. i B i C i D i (where i is the electronic nautical chart sheet number), and generate a rectangular polygon using these four points. Determine whether the rectangular polygon intersects topologically with the task sea area, thereby obtaining all electronic nautical charts that intersect topologically with the task sea area.

[0044] Step 2: Based on the definitions in the electronic chart data dictionary, extract the navigational obstructions contained in each electronic chart, including point-shaped, line-shaped, and area-shaped navigational obstructions;

[0045] Step 3: Find the overlapping range of multiple nautical charts, extract navigational obstructions from different nautical charts within the overlapping range, determine whether there is a topological intersection of navigational obstructions, if so, perform a merge operation, for non-overlapping areas, retain the navigational obstruction data of a single nautical chart, and save the set W0 of all navigational obstructions in vector data format;

[0046] Step 4: To reserve a safe buffer distance for obstructions, point-shaped obstructions are expanded outward into square obstruction zones, linear obstructions are expanded into polygonal obstruction zones through translation and extension, and planar obstruction zones are expanded using the angle bisector method (preserving their original concavity and convexity). The combined obstruction zones after processing are W. D ;

[0047] Among them, the safe distance reserved for obstructions is Where r is the turning radius of the ship, e is the positioning error, b is the width of the ship, and D0 is the margin.

[0048] Point-shaped obstructions are expanded into square obstruction zones by extending D in both the horizontal and vertical directions. Linear obstructions are extended by D at both the starting and ending points, and then shifted inward and outward by a safe distance D along the perpendicular direction connecting the starting and ending points of the linear obstruction, thereby expanding into polygonal obstruction zones.

[0049] The planar obstruction zone is expanded using the angle bisector method. This involves traversing each vertex of the obstruction zone and calculating the position of the expanded vertex based on the angle bisector. For special cases where calculations for concave polygons may fail, adjustments are made by superimposing a condition to determine whether the expanded vertex is outside the obstruction zone. This completes the expansion of the planar obstruction zone. Similar to linear obstructions, the expansion of the planar obstruction zone involves reserving a safety distance D and preserving the overall concave-convex characteristics of the original obstruction zone.

[0050] Step 5: Simplify the buffered obstruction zones by hierarchical level, such as... Figure 2 As shown, Level I simplification involves using the sliding window area method to remove redundant vertices in the navigation obstruction area while retaining the original concavity and convexity characteristics, resulting in the set W of navigation obstructions after Level I simplification. Ⅰ The Level II simplification involves finding the convex hull of the obstruction zone, resulting in the Level II simplified obstruction zone set W. Ⅱ ;

[0051] The specific steps of the sliding window area method in step 5 include:

[0052] 5.1. The sliding window area method is used to simplify the navigation obstruction area with a large number of vertices. Based on the principle that half of the vector cross product is the directed area (positive and negative) of the triangle formed by two vectors, the necessary vertices of the navigation obstruction area are selected by calculating the cumulative directed area value.

[0053] 5.2 Starting from the initial vertex of the obstruction zone, take three consecutive vertices P0, P1, and P2 in sequence to form two vectors P0P1 and P0P2. Calculate the directed area S of the vector triangle formed by the current three vertices, which is half of the cross product of vectors P0P1 and P0P2.

[0054] 5.3 Compare the calculated area value S with the set threshold. If it is greater than the given threshold, then the middle vertex P1 is determined to be a necessary vertex and saved. The sliding windows P0, P1, and P2 are moved one position to the right as a whole, and the calculated area S is cleared to zero. If it is not greater than the given threshold, then the middle vertex P1 is determined to be a non-necessary vertex and deleted. P1 and P2 are moved one position to the right in turn, while P0 remains unchanged. The calculated area value S is accumulated without being cleared until the accumulated area value is greater than the given threshold. The sliding windows of P0, P1, and P2 are moved to the right as a whole.

[0055] 5.4 Repeat step 5.3 above until P2 moves to the endpoint;

[0056] 5.5. Retain all necessary vertices on the obstruction and delete the remaining redundant vertices to obtain the Level I simplified obstruction zone polygon.

[0057] Step 6: Input the starting and ending points, and first obtain the Level II simplified obstruction zone set W.Ⅱ Determine whether the starting point and the ending point are located within the obstruction zone. If the starting point or the ending point is located within the obstruction zone, proceed to step 7; otherwise, proceed to step 8.

[0058] Step 7: Obtain the Level I Simplified Obstruction Zone W Ⅰ This serves as an obstacle environment for the current task area, and then proceeds to step 9;

[0059] Step 8: Neither the starting point nor the ending point is located in Class II navigational obstruction zone W. Ⅱ If no reachable path can be found, proceed to step 9 to find the optimal path. If no reachable path can be found, proceed to step 7.

[0060] Step 9: Based on the environmental space within the current task area, establish a route binary tree, find the obstruction zone closest to the starting point, detour from the left and right sides, generate left and right subtrees in a loop, and after constructing the global binary tree, find the shortest route from the starting point to the destination.

[0061] The specific steps of step 9 include:

[0062] Step 9.1: Find the obstruction zone closest to the starting point, detour from the left and right sides, and check whether it exceeds the task area and causes the current path to be blocked, thereby constructing left and right subtrees with boundary constraints;

[0063] Step 9.2: After the global binary tree is constructed, access the cumulative length value of all feasible paths, select the shortest path, find the node index corresponding to the end point of the path, and trace back layer by layer upwards through the parent node index until the starting point is reached, thereby generating the shortest route from the starting point to the end point.

[0064] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, alterations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for fast route generation based on vector electronic chart, characterized in that: It comprises the following steps: Step 1, obtaining the position of the task sea area according to the navigation task, and obtaining all the electronic sea charts related to the task sea area; Step 2, according to the definition of electronic chart data dictionary, extracting the navigation-obstructing objects contained in each electronic chart, including point-like, line-like and surface-like navigation-obstructing objects; Step 3, obtaining the overlapping range of multiple charts, extracting the navigation-obstructing objects from different charts in the overlapping range, judging whether there is a topological intersection of navigation-obstructing objects, if there is, performing the union operation, and for the non-overlapping area, retaining the navigation-obstructing object data of a single chart, and saving all the navigation-obstructing object data in vector data format; Step 4, buffer processing of the navigation-obstructing objects, including: according to the safety distance reserved for the navigation-obstructing objects, expanding the point-like navigation-obstructing objects in the navigation-obstructing object data saved in step 3 into square navigation-obstructing areas, expanding the linear navigation-obstructing objects into polygon navigation-obstructing areas by translation and elongation, and expanding the surface navigation-obstructing areas by using the angle bisector method; Step 5, simplifying the navigation-obstructing areas after buffer processing, the first level simplification adopts the sliding window area method to delete the redundant vertices of the navigation-obstructing areas while retaining the original concave-convex characteristics; the second level simplification is to obtain the convex hull of the polygon navigation-obstructing area, and save all the simplified navigation-obstructing area data; Step 6, inputting the start point and end point positions of the route to be generated, first obtaining the second level simplified navigation-obstructing area set, judging whether the start point and end point are located in the navigation-obstructing area, if the start point or end point is located in the navigation-obstructing area, jumping to step 7, otherwise jumping to step 8; Step 7, obtaining the first level simplified navigation-obstructing area as the obstacle environment of the current task area, and then jumping to step 9; Step 8, neither the start point nor the end point is located in the second level navigation-obstructing area, jumping to step 9 to find the optimal path, if no reachable path is found, jumping to step 7; Step 9, establishing a route binary tree based on the environment space in the current task area, finding the navigation-obstructing area closest to the start point, and performing detour from both sides to generate left and right sub-trees, and then constructing a global binary tree to find a shortest route from the start point to the end point.

2. The method for fast route generation based on vector electronic chart according to claim 1, characterized in that: The specific method of step 1 is: According to the navigation task, the position of the task sea area is obtained, the description data of the chart sheet in the electronic chart metadata is obtained, the four points of the electronic chart sheet are obtained, and a rectangular polygon is generated based on the four points, and it is judged whether the rectangular polygon is topologically intersected with the task sea area, so as to obtain all the electronic charts topologically intersected with the task sea area.

3. The method for fast route generation based on vector electronic chart according to claim 1, characterized in that, In step 4, the safety distance reserved for the obstacle is: ； wherein, R is the turning radius of the ship, E is the positioning error, W is the width of the ship, R is the surplus amount.

4. The method for fast route generation based on vector electronic chart according to claim 3, characterized in that, The specific steps of step 4 include: Step 4.1, the specific method of expanding the linear navigation-obstructing objects into polygon navigation-obstructing areas by translation and elongation is: elongating the start point and end point of the linear navigation-obstructing objects by the reserved safety distance, respectively, and then translating the two points along the vertical direction of the line connecting the start point and end point to both sides, respectively, the polygon composed of the two lines after translation is the polygon navigation-obstructing area formed by expanding the linear navigation-obstructing objects; Step 4.2, expanding the surface navigation-obstructing area outward by the reserved safety distance, and maintaining the overall concave-convex characteristics of the original navigation-obstructing area during the expansion processing.

5. The method for fast route generation based on vector electronic chart according to claim 1, characterized in that, The specific steps of the sliding window area method in step 5 include: Step 5.1, the area method of sliding window is used to simplify the navigation-obstructing area with a large number of vertices, and the necessary vertices of the navigation-obstructing area are screened out according to the principle that half of the vector cross product is the directed area of the triangle formed by two vectors, and the cumulative directed area value is calculated; Step 5.2, starting from the starting vertex of the navigation-obstructing area, three consecutive vertices are taken in turn, and the directed area of the vector triangle formed by the three vertices is calculated; Step 5.3, the calculated area value is compared with the set threshold value, if it is greater than the set threshold value, it is judged that the middle vertex is a necessary vertex and is saved, the sliding window is pushed back by one position as a whole, and the calculated area is cleared, if it is not greater than the set threshold value, it is judged that the middle vertex is a non-essential vertex and is deleted, the last two vertices are slid back by one position in turn, the first vertex remains unchanged, and the calculated area value is accumulated until the accumulated area value is greater than the set threshold value, and the sliding window of the three vertices is pushed back as a whole; Step 5.4, repeat the above step 5.3 operation until all vertices of the navigation-obstructing area are traversed; Step 5.5, keep all necessary vertices of the navigation-obstructing area, delete the remaining redundant vertices, and obtain the I-level simplified navigation-obstructing area polygon.

6. The method for fast route generation based on vector electronic chart according to claim 1, characterized in that, The specific steps of step 9 include: Step 9.1, find the navigation-obstructing area closest to the starting point, and perform a detour from the left and right sides to check whether the current side path is blocked due to exceeding the task area, thereby constructing left and right sub-trees with boundary restrictions; Step 9.2, after the global binary tree is constructed, the cumulative length values of all feasible paths are accessed, the shortest path is selected, the node index corresponding to the end point of the shortest path is found, the father node index is traced back layer by layer upwards until the starting point is reached, thereby generating the shortest navigation route from the starting point to the end point.

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