1 research outputs found
Coastal path planning algorithm using quadtree and visibility graph
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Όλ¬Έ(λ°μ¬) -- μμΈλνκ΅λνμ : 곡과λν μ‘°μ ν΄μ곡νκ³Ό, 2021.8. κΉνμ.With the introduction of e-Navigation technology by the International Maritime Organization, it has been recommended for ships to exchange data with maritime centers. For this purpose, the necessary information for ships is electronically exchanged for information exchange, and this information includes route information. Therefore, the vessel must make a voyage plan and transmit it to the maritime center. Maritime center must check that there is no problem in the voyage plan and send the voyage plan to the vessel. Since weather routing system is established for ships sailing the ocean, it is easy to exchange route data between ships and maritime center. However, it is difficult to exchange route data for coastal ships because the navigator decide the route manually using their professional knowledge. In order to compensate the manual route planning along with the digitalization of the route, the demand for an automatic route system in the coast has increased.
Coastal ships include passenger ships, fishing boats, and yachts for various purposes. Vessels must calculate the route to their destination to achieve their objectives. The purpose of this study is to compute a safe and efficient route within a coast with a complex environment. It is necessary to secure the safety of the vessel by providing a route plan in consideration of the changing marine environment to the vessel in operation before departure or in real time. In order to determine a route, information such as shoreline, water depth, weather, and tide is required. Based on this information, many studies on route planning of ships sailing the ocean have been developed, but most of them are focused on reducing fuel consumption and sailing time in open sea. Because the coastline is complex and there are many obstacles in the coast, it is difficult to apply the existing research in coastal environment. In addition, since there are many areas with a large tide difference in Korea, the environment changes frequently during navigation. Therefore, it is necessary to calculate the route within a short time to consider frequent environment change.
In this paper, we propose a novel route planning algorithm for complex offshore environments by integrating the advantages of quadtree and visibility graph. A quadtree is used to improve the inefficient environment representation method such as the uniform grid. The graph is constructed using quadtree and the shortest path is computed on the quadtree based graph. Using the waypoints of the previously computed route, a visibility graph is generated to calculate the optimal route. To find the optimal path, Dijkstra algorithm is used at this time. The proposed algorithm can perform route planning from any angle and establishes a safe route plan by maintaining a certain distance from the coastline. In addition, the fuel consumption is computed in consideration of the weather information according to the departure time of the vessel, and the route with the minimum fuel consumption is planned. To calculate the fuel consumption, the braking power must be computed. The braking power can be calculated from the effective power, which is composed of the ship's resistance and speed. The resistance of the vessel is composed of resistance in still water, additional wind resistance, and additional wave resistance, and the net speed of the vessel. At this time, the additional resistance and the speed of the ship are computed based on ISO 15016. For validation of proposed algorithm, the minimum fuel consumption route and the shortest distance route were compared and evaluated. For performance evaluation, the algorithm proposed in this study was applied to the west and south sea of Korea. It was confirmed that the topology of the minimum fuel consumption route was different from the shortest route due to the influence of the weather information. Overall, it was confirmed that the proposed algorithm can generate the optimal route in complex environment with a short time.κ΅μ ν΄μ¬κΈ°κ΅¬(International Maritime Organization)κ° e-Navigation κΈ°μ μ λμ
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1.1 Background 1
1.2 Objective and method 3
1.3 Contributions of this paper 8
1.4 Outline 9
2 Theoretical background 10
2.1 Environment modelling 14
2.1.1 Regular grids 14
2.1.2 Irregular grids 16
2.1.3 Navigation mesh 17
2.1.4 Voronoi diagram 19
2.1.5 Visibility graph 20
2.1.6 Comparison of environment modeling 21
2.2 Path planning methods 24
2.2.1 Graph based methods 24
2.2.2 Sampling based methods 26
2.2.3 Evolutionary methods 29
2.2.4 Comparison of path planning methods 32
3 Related work 33
3.1 Genetic algorithm with navigation mesh 33
3.2 Dijkstra algorithm with Voronoi diagram 34
3.3 A* algorithm with quadtree 35
3.4 Comparison of related works with this thesis 38
4 Data acquisition and preprocess 43
4.1 Topography data 43
4.1.1 Topography and depth 43
4.1.2 Coastline expansion algorithm 46
4.2 Weather data 51
4.2.1 Wave data (KMA) 52
4.2.2 Wind data (KMA) 54
4.2.3 Current data (KMA) 56
4.2.4 Tide data (KHOA) 58
5 Quadtree based graph 60
5.1 Quadtrees 60
5.2 PMR quadtree insertion and split algorithm 67
5.3 Graph construction using PMR quadtree 76
5.4 The shortest path on quadtree based graph 85
6 Visibility graph construction with quadtree 87
6.1 Visibility graph 87
6.2 Visibility graph with quadtree 90
6.3 Improved line of sight algorithm 91
7 Fuel oil consumption estimation 94
7.1 Ship resistance 94
7.2 Ship speed 100
7.3 Fuel oil consumption 101
7.4 Example of fuel oil consumption computation 103
8 Coastal path planning algorithm 107
8.1 Problem definition 107
8.2 Assumptions for route optimization 109
8.3 Procedure of coastal path planning algorithm 109
9 Experimental results 113
9.1 Simulation results in quadtree generation 113
9.2 Simulation results with different draft 115
9.3 Simulation results in south sea of Korea 119
9.4 Simulation results in west sea of Korea 134
9.5 Fuel oil consumption minimization path results 148
9.5.1 First case in west sea of Korea 148
9.5.2 Second case in west sea of Korea 156
9.5.3 Third case in south sea of Korea 161
9.5.4 Second case in south sea of Korea 169
9.6 Long voyage path results 174
10 Conclusion and future works 179
References 181λ°