Path planning method based on hierarchical simplified map

Abstract

The application discloses a path planning method based on a hierarchical simplified map, and specifically comprises the following steps: S1, connecting stations according to driving paths to form a bottom layer map; S2, extracting a maximum connected region in the bottom layer map; S3, performing hierarchical simplification on the maximum connected region to form a hierarchical simplified map; and S4, planning a shortest driving path from a starting station to a target station based on the hierarchical simplified map. The map is simplified layer by layer to make the map reach a most simple state, and the hierarchical simplified map is used for path planning, so that the planning efficiency of vehicle path planning is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of path planning technology, and more specifically, this invention relates to a path planning method based on a hierarchical simplified map. Background Technology

[0002] With the rapid development of modern technology, manual labor is gradually being replaced by automated machinery. As my country's technological level improves, traditional processing and manufacturing plants are increasingly moving towards intelligent and unmanned operations. The transportation of raw materials and finished products within factories has evolved from manual labor to AGVs (Automated Guided Vehicles) that transport goods via magnetic tracks. Commonly used magnetic track-guided AGVs in factories are mobile robot solutions that travel unidirectionally along pre-set circular magnetic tracks. However, with increasing production demands, the number of magnetic tracks in the workplace is also increasing. These tracks are connected by branching points, making the AGV scheduling system map increasingly complex and reducing its scheduling efficiency.

[0003] For example, in application number CN201811601116.5, invention title: A path planning method for AGV, after receiving task information, the method plans the shortest travel path from the task start point to the task end point based on the overall map. Directly using the overall map for path planning results in low scheduling planning efficiency of the AGV scheduling system due to the excessive complexity of the overall map. Summary of the Invention

[0004] This invention provides a path planning method based on a hierarchical simplified map, aiming to improve the above-mentioned problems.

[0005] This invention is implemented as follows: a path planning method based on a hierarchical simplified map, the method specifically including the following steps:

[0006] S1. Connect the stations according to the driving route to form the underlying map;

[0007] S2. Extract the largest connected region in the underlying map;

[0008] S3. Simplify the largest connected region into a hierarchical simplified map;

[0009] S4. Based on a hierarchical simplified map, plan the shortest driving path from the starting station to the target station.

[0010] Furthermore, the method for forming a hierarchical simplified map is as follows:

[0011] S31, First-level simplification: Merge adjacent paths with the same attributes in the bottom-level map to form a first-level simplified map;

[0012] S32, Second Layer Simplification: Hides the material loading points within the traffic control area on the first layer map to form a second layer simplified map;

[0013] S33, Third-level simplification: Hides the non-shortest path between two main stations on the second-level simplified map to form a third-level simplified map.

[0014] Furthermore, the second-level simplification process is as follows:

[0015] In the first-layer simplified map, a traffic control area consisting of one branch road segment and at least one main road segment is detected. If the in-degree of the main station intersecting the branch road segment within the traffic control area is greater than or equal to 2, the material loading station in the traffic control area is hidden. The identifier of the hidden station is added to the intermediate station set corresponding to the main road segment. The branch road segment and main road segment where the hidden station is located are added to the sub-area where the corresponding two main stations are located, thus forming the second-layer simplified map.

[0016] Furthermore, the first-level simplification process is as follows:

[0017] S311. Check whether the current main road segment and the next main road segment have the same road direction, and whether the out-degree of the connecting station of the two main road segments is 1. If the detection results are both yes, then the attributes of the two main road segments are considered to be the same. Hide the connecting station of the two main road segments in the underlying map and add the identifier of the connecting station to the intermediate station set corresponding to the merged road segment where the main stations on both sides are located.

[0018] S312. Take the next main road segment as the current main road segment and execute step S311 until all main road segments in the current largest connected region have been traversed.

[0019] Furthermore, the third-level simplification process is as follows:

[0020] S331. In the second-level simplified map, find each main station A with an out-degree greater than or equal to 2. Starting from the direction corresponding to the out-degree of each main station A, find the next identical main station B on the corresponding path.

[0021] S332. Obtain all paths between main stations A and B, add the identifiers of each sub-region that make up the non-shortest path to the sub-region set of the area where main stations A and B are located, and add the representations of all stations on the non-shortest path to the intermediate station set corresponding to the two main stations.

[0022] S333, repeat step S331 until there are only two main stations forming a closed-loop driving path on the second-level simplified map, which is the third-level simplified map.

[0023] Furthermore, the path planning method specifically includes the following steps:

[0024] Determine the road segment R1 of the current starting station in the third-level simplified map;

[0025] Check if the target station is also located on road segment R1. If the result is no, that is, the target station is located on road segment R2 in the third layer map, then search for path 1 from the starting station to the ending station L1 of road segment R1 and path 2 from the starting station of road segment R2 to the target station in the area where road segment R2 and road segment R1 are located, layer by layer. The connection of path 1 and path 2 forms the shortest path from the starting station to the target station.

[0026] Furthermore, if the starting station and the target station are located on the same road segment R1 in the third layer map, then it is checked whether the direction from the starting station to the target station is the same as the direction of the road segment R1.

[0027] If the directions are the same, then search for the shortest path from the starting station to the target station layer by layer in the area where road segment R1 is located.

[0028] Furthermore, if the starting station and the target station have different directions, then in the area where road segment R1 is located, find path 3 from the starting station to the ending station L1 of road segment R1. The road segment set in the area where path R2 is located constitutes path 4. In the area where road segment R1 is located, find path 5 from the ending station of road segment R2 to the target station. The sequential connection of path 3, path 4 and path 5 constitutes the shortest travel path from the starting station to the target station.

[0029] Furthermore, based on the Tarjan algorithm, strongly connected regions are extracted from the underlying map, and these strongly connected regions are the largest connected regions.

[0030] This invention simplifies the map layer by layer to achieve the simplest state, and uses the simplified hierarchical map for route planning, which greatly improves the planning efficiency of vehicle route planning. Attached Figure Description

[0031] Figure 1 A flowchart of a path planning method based on a hierarchical simplified map provided in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the underlying map provided in an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of a first-layer simplified map provided in an embodiment of the present invention;

[0034] Figure 4 A schematic diagram of a second-layer simplified map provided in an embodiment of the present invention;

[0035] Figure 5 A schematic diagram of a simplified intermediate map of the third layer provided in an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of a simplified third-layer map provided in an embodiment of the present invention. Detailed Implementation

[0037] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0038] Figure 1 The flowchart of the path planning method based on a hierarchical simplified map provided in this embodiment of the invention includes the following steps:

[0039] S1. Connect the stations according to the driving route to form the underlying map;

[0040] In this embodiment of the invention, the station includes a main station and a loading station on the magnetic navigation system. The road segment between the main stations is called the main road segment, and the road segment between the main station and the loading station is called the branch road segment. The branch road segment is bidirectional, the main road segment is unidirectional, and the main path composed of the main road segments is a unidirectional closed loop spin.

[0041] S2. Extract strongly connected regions from the underlying map based on the Tarjan algorithm;

[0042] In this embodiment of the invention, due to the unidirectional closed-loop spin of the main path, a strongly connected region is extracted in the underlying map.

[0043] S3. Simplify strongly connected regions into hierarchical simplified maps.

[0044] In this embodiment of the invention, each maximum connected region in the underlying map is simplified in three layers as follows, and the specific simplification process is as follows:

[0045] S31. First-level simplification: In the bottom-level map, adjacent paths with the same attributes are merged to form a first-level simplified map. The specific process of the first-level simplification is as follows:

[0046] S311. Detect whether the current main road segment and the next main road segment have the same road direction, and whether the out-degree of the connecting station of the two main road segments is 1. If the detection results are both yes, then the attributes of the two main road segments are considered to be the same. Hide the connecting station of the two main road segments in the underlying map and add the identifier of the connecting station to the intermediate station set corresponding to the merged road segment where the main stations on both sides are located.

[0047] S312. Take the next main road segment as the current main road segment and execute step S311 until all main road segments in the current largest connected region have been traversed.

[0048] S32. Second-layer simplification: Hides the material loading points within the traffic control area on the first-layer map to form a second-layer simplified map. The specific process of the second-layer simplification is as follows:

[0049] In the first-layer simplified map, a traffic control area consisting of one branch road segment and at least one main road segment is detected. If the in-degree of the main station where the main road segment intersects with the branch road segment in the traffic control area is greater than or equal to 2, the loading station in the traffic control area is hidden. The identifier of the hidden station is added to the intermediate station set corresponding to the main road segment. The branch road segment and main road segment where the hidden station is located are added to the sub-area where the corresponding two main stations are located, forming the second-layer simplified map. If the in-degree of the intersecting main stations in the traffic control area is greater than or equal to 2, and there is at least one one-way main road segment and one two-way branch road segment among the multiple road segments entering the main station.

[0050] S33. Third-level simplification: The non-shortest path between two main stations is hidden on the second-level simplified map to form a third-level simplified map. The specific process of the third-level simplification is as follows:

[0051] S331. In the second-level simplified map, find each main station A with an out-degree greater than or equal to 2. Starting from the direction corresponding to the out-degree of each main station A, find the next identical main station B on the corresponding path.

[0052] S332. Obtain all paths between main stations A and B, add the identifiers of each sub-region that make up the non-shortest path to the sub-region set of the area where main stations A and B are located, and add the representations of all stations on the non-shortest path to the intermediate station set corresponding to the two main stations.

[0053] S333, repeat step S331 until there are only two main stations forming a closed-loop driving path on the second-level simplified map, which is the third-level simplified map, also known as the highest-level simplified map.

[0054] The first-level simplified map, the second-level simplified map, and the third-level simplified map mentioned above constitute a hierarchical simplified map.

[0055] Combination Figures 2 to 6 The specific embodiments shown illustrate the simplification process of the underlying map described above in detail, as follows:

[0056] Figure 2 The underlying map is shown in Table 1. Figure 2 Corresponding data table information in the underlying map;

[0057] Table 1. Data table information in the underlying map.

[0058]

[0059]

[0060] If the road segment edge-3 between main station 4 and main station 6, the road segment edge-4 between main station 6 and main station 7, and the road segment edge-5 between main station 7 and main station 8 have the same road segment attributes, then main station 6 and main station 7 are hidden. Similarly, if the road segment edge-9 between main station 9 and main station 11, the road segment edge-10 between main station 11 and main station 12, and the road segment edge-11 between main station 12 and main station 13 have the same road segment attributes, then main station 11 and main station 12 are hidden. This forms the first layer of simplified map, as shown below. Figure 3 As shown, the corresponding data table information is shown in Table 2;

[0061] Table 2. Data information for the first-level simplified map.

[0062] Path ID starting point end Is it bidirectional? intermediate nodes Weight Is it the main road? road1 1 2 0 0 1 1 road2 2 4 0 0 1 1 road3 4 8 0 6-7 3 1 road4 8 9 0 0 1 1 road5 9 13 0 11-12 3 1 road6 13 1 0 0 1 1 road7 1 8 0 0 1 1 road8 1 15 1 0 1 0 road9 2 3 1 0 1 0 road10 4 5 1 0 1 0 road11 9 10 1 0 1 0 road12 13 14 1 0 1 0 road13 13 9 0 0 1 1

[0063] The main road segment (road1) and the secondary road segment (road9) form a traffic control area. Station 3 is hidden, and the route markers for main road segment (road1) and secondary road segment (road9) are added to sub-area 1. The main road segment (road2) and the secondary road segment (road10) form a traffic control area. Station 5 is hidden, and the route markers for main road segment (road2) and secondary road segment (road10) are added to sub-area 2. The main road segment (road5) and the secondary road segment (road12) form a traffic control area. Station 14 is hidden, and the route markers for main road segment (road5) and secondary road segment (road12) are added to sub-area 7. The main road segment (road6) and the secondary road segment (road8) form a traffic control area. Station 15 is hidden, and the road segment markers for main road segment (road6) and secondary road segment (road8) are added to sub-area 8. The main road segment (road4) and the secondary road segment (road11) form a traffic control area. Station 10 is hidden, and the main road segment (road4) and secondary road segment (road11) are added to sub-area 5. This forms a second-layer simplified map, as follows: Figure 4 As shown, the corresponding data table information is shown in Table 3;

[0064] Table 3. Data information for the second-level simplified map.

[0065] Region ID starting point end intermediate nodes Path ID Weight Traffic management strategy 1 1 2 3 1-9 1 Traffic control area 2 2 4 5 2-10 1 Traffic control area 3 4 8 6-7 3 3 Non-traffic control area 4 1 8 0 7 1 Non-traffic control area 5 8 9 0 4-11 1 Traffic control area 6 9 13 11-12-14 5-12 3 Traffic control area 7 13 1 15 6-8 1 Traffic control area 8 13 9 0 13 1 Traffic control area

[0066] The out-degree of main station 1 is 2. Starting from the corresponding directions of the two out-degrees, the next station on both paths is the same: main station 8. There are two paths from main station 1 to 8: 1→2→4→8 and 1→8. Since path 1→8 is shorter, sub-region 1 containing road1 and road9, sub-region 2 containing road2 and road10, and sub-region 3 containing road3 are hidden in the region -1ST 2 containing main station 1 and main station 8. Sub-region 4 containing road7 is not hidden, but is also added to the region -1ST 2 containing station 1 and main station 8. Figure 5 As shown, the corresponding data table is shown in Table 4;

[0067] Table 4. Data table of the third-layer simplified intermediate map

[0068] Region-1ST id starting point end intermediate nodes Subregion ID Weight 1 13 1 15 7 1 2 1 8 2-3-4-5-6-7 1-2-3,4 1 3 8 9 10 5 1 4 9 13 11-12-14 6 3 5 13 9 0 8 1

[0069] The out-degree of main station 13 is 2. Starting from the corresponding directions of the two out-degrees, the next station on both paths is the same: main station 9. There are two paths from main station 13 to main station 9: 13→1→8→9 and 13→9. Since the path 13→9 is shorter, the following areas are hidden: -1ST 1 (main station 13 and main station 1), -1ST 2 (main station 1 and main station 8), and -1ST 3 (main station 8 and main station 9). Areas -1ST 1, -1ST 2, and -1ST 3 are hidden within area 1 (main station 13 and main station 9). Area -1ST 5 (road 13 and road 9) is not hidden but is also added to area 1 (main station 13 and main station 9). The simplified map of the third layer is as follows: Figure 6 As shown in Table 5, the data table corresponding to the third-layer simplified map is shown in Table 5.

[0070] Table 5. Data table of the third-level simplified map

[0071] Region ID starting point end intermediate nodes Region-1ST-id Weight 1 13 9 1-2-3-4-5-6-7-8-9-10-15 1-2-3,5 1 2 9 13 11-12-14 4 3

[0072] S4. Based on a hierarchical simplified map, plan the shortest driving path from the starting station to the target station.

[0073] In this embodiment of the invention, the path planning method specifically includes the following steps:

[0074] Determine that the current starting station is on road segment R1 in the simplified map of the third layer. Check whether the target station is also located on road segment R1. If the target station is located on road segment R2 in the map of the third layer, then search for path 1 from the starting station to the ending station L1 of road segment R1 and path 2 from the starting station of road segment R2 to the target station in the area where road segment R1 and road segment R1 are located, layer by layer. The connection between path 1 and path 2 forms the shortest path from the starting station to the target station.

[0075] If the starting station and the target station are located on the same road segment R1 in the third layer map, then check whether the direction from the starting station to the target station is the same as the direction of the road segment R1.

[0076] If the directions are the same, the shortest path from the starting station to the target station is searched layer by layer in the area where road segment R1 is located. If the directions are different, path 3 from the starting station to the ending station L1 of road segment R1 is searched in the area where road segment R1 is located. The road segment set in the area where path R2 is located forms path 4. Path 5 from the ending station of road segment R2 to the target station is searched in the area where road segment R1 is located. The sequential connection of path 3, path 4 and path 5 forms the shortest travel path from the starting station to the target station.

[0077] The present invention has been described by way of example. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A path planning method based on a hierarchical simplified map, characterized in that, The method specifically includes the following steps: S1. Connect the stations according to the driving route to form the underlying map; S2. Extract the largest connected region in the underlying map; S3. Simplify the largest connected region into a hierarchical simplified map; S4. Based on a hierarchical simplified map, plan the shortest driving path from the starting station to the target station; The specific method for creating a hierarchical simplified map is as follows: S31, First-level simplification: Merge adjacent paths with the same attributes in the bottom-level map to form a first-level simplified map; S32, Second-level simplification: Hides the material loading points within the traffic control area on the first-level simplified map to form a second-level simplified map; S33, Third-level simplification: Hides the non-shortest path between two main stations on the second-level simplified map to form a third-level simplified map; The second-level simplification process is as follows: In the first-layer simplified map, a traffic control area consisting of one branch road segment and at least one main road segment is detected. If the in-degree of the main station intersecting the branch road segment within the traffic control area is greater than or equal to 2, the material loading station in the traffic control area is hidden. The identifier of the hidden station is added to the intermediate station set corresponding to the main road segment. The branch road segment and main road segment where the hidden station is located are added to the sub-area where the corresponding two main stations are located, thus forming the second-layer simplified map.

2. The path planning method based on a hierarchical simplified map as described in claim 1, characterized in that, The first-level simplification process is as follows: S311. Check whether the current main road segment and the next main road segment have the same road direction, and whether the out-degree of the connecting station of the two main road segments is 1. If the detection results are both yes, then the attributes of the two main road segments are considered to be the same. Hide the connecting station of the two main road segments in the underlying map and add the identifier of the connecting station to the intermediate station set corresponding to the merged road segment where the main stations on both sides are located. S312. Take the next main road segment as the current main road segment and execute step S311 until all main road segments in the current largest connected region have been traversed.

3. The path planning method based on a hierarchical simplified map as described in claim 1, characterized in that, The third-level simplification process is as follows: S331. In the second-level simplified map, find each main station A with an out-degree greater than or equal to 2. Starting from the direction corresponding to the out-degree of each main station A, find the next identical main station B on the corresponding path. S332. Obtain all paths between main stations A and B, add the identifiers of each sub-region that make up the non-shortest path to the sub-region set of the area where main stations A and B are located, and add the representations of all stations on the non-shortest path to the intermediate station set corresponding to the two main stations. S333, repeat step S331 until there are only two main stations forming a closed-loop driving path on the second-level simplified map, which is the third-level simplified map.

4. The path planning method based on a hierarchical simplified map as described in claim 1, characterized in that, The path planning method specifically includes the following steps: Determine the road segment R1 of the current starting station in the third-level simplified map; Check if the target station is also located on road segment R1. If the result is no, that is, the target station is located on road segment R2 in the third layer map, then search for path 1 from the starting station to the ending station L1 of road segment R1 and path 2 from the starting station of road segment R2 to the target station in the area where road segment R2 and road segment R1 are located, layer by layer. The connection of path 1 and path 2 forms the shortest path from the starting station to the target station.

5. The path planning method based on a hierarchical simplified map as described in claim 4, characterized in that, If the starting station and the target station are located on the same road segment R1 in the third layer map, then check whether the direction from the starting station to the target station is the same as the direction of the road segment R1. If the directions are the same, then search for the shortest path from the starting station to the target station layer by layer in the area where road segment R1 is located.

6. The path planning method based on a hierarchical simplified map as described in claim 5, characterized in that, If the starting station and the destination station have different directions, then in the area where the road segment R1 is located, find path 3 from the starting station to the ending station L1 of the road segment R1. The road segment set in the area where path R2 is located forms path 4. In the area where the road segment R1 is located, find path 5 from the ending station of the road segment R2 to the destination station. The sequential connection of path 3, path 4 and path 5 forms the shortest travel path from the starting station to the destination station.

7. The path planning method based on a hierarchical simplified map as described in claim 1, characterized in that, The Tarjan algorithm is used to extract strongly connected regions from the underlying map, which are the largest connected regions.

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