Research On Route Planning Method Based On Electronic Chart

Marine intelligent transportation system is significant for improving maritime traffic condition, safeguarding shipping safety and water environment. As a key technology of intelligent navigation syste, ship route planning is an important matter for application of electronic chart. Utilizing modern network technology and information fusion technology to achieve physical connections and information integration of various navigation systerm, and adopts intelligent information processing technology to achieve high accuracy, high reliability and automation navigation is an important topic of navigation society.With the background of maritime intelligent transportation system, the paper makes systematic research on ship route planing method by combining characteristics of marine environmental complexity, dynamic and uncertainty, as it is followed:(1) Research on ship route network modeling methodAs basis of ship route planning, environmental model delivers environment recognition information efficiently by forms of network and grid. The existing method is limited to application in local path planing for must possessing complete environment information in advance. Combining unknown characteristics of environmental information in local route planning, the concept of virtual obstacle is introduced, according to the realtime local environmental information detected; a structure of dynamic detecting line is constructed for decompositon of complicated environmental information effectively. Using relevant theory of convex hull of computation geometry for reference, traditional tangent graph modeling method is improved, by which environmental model in complicated and unknown environment is constructed effectively.(2) Research on ship route planning method under static maritime environmentExisting methods for route planning are almost around small range and are not applicable for wide range marine environment. According to the sparse characteristic of obstacles under large-scale marine environment, the strategy of limited searching area and collision detection are adapted for the constrction of potential collision set. The obstacles are decomposed based on grid model for its advantages of simpleness and powerful express ability for irregular obstacles, a compact and effective environment model is built by extracting the boundary information of obstacles and the shortest ship route is achieved by elasticity algorithm which makes full use of the adjacency relation of grids.(3) Research on route planning method under uncertain and dynamic environment The variation of marine environmental information is uncertain and which is difficult for the resolution of the problems by traditional overall planning method. By using the idea of rolling optimization for reference, the route on-line replanning is realized by combination of optimization and feedback mechanism. The scene in rolling window is forecast according to the track model of dynamic obstacles, which uses the method for moving form descripiton in physics. Aiming on the problem of large redundancy of standard Bug algorithm, a function named route utility assessment and recalling route fusion mechanisim is adapted for the improvement and optimization of the Bug algorithm.(4) Research on integration method for excesive information under ECDIS platformComplete and accurate environmental information is the premise of route planning. Realizing the data analysis and display of authoritative ECDIS based on the international S-57 standard. Combining long sequence remote sensing data, study and analysis is made for the time-space variation of hydrometeorological factors in specific sea area by the use of time-space analysis model, the hydrometeorological information and ECDIS are superposition displayed based on Mercator projection. The method provided offers a helpful technology reference for multi-information integration under ECDIS.This dissertation takes the key technologies of route planning as research objects and the main innovations are summarized as follows:(1) An environmental model of incremental tangent graph based on convex hullThe method can better accommodate the unknown environmant information characteristic of local planning. Time complexitiy is linear and can satisfy the realtime requirement of environment modeling in online route planning. Meanwhile, which can decrease the sacle of environment map effectively and ulteriorly the computation cost expecially in large scale complicated environment.(2) An Elasticity algorithm based on potential colllision set for overall planningThe Elasticity algorithm makes full use of the adjancy relations of grids and has higher searching efficiency. It is not sensitive to the size of the space of environmental planning and has advantages of better precision and stability. The algorithem can be applied in large scale complicated environment and has strong applicability, especially in marine envrionment with relative sparse obstacles.(3) An improved Bug algorithm based on rolling window for local planningThe algorithm can better accommodate the uncertain influence of marine environment and realize route planning in unknown and dynamic environment. It can assure planning results to be convergent and has characteristics of better applicability and realtime, which can satisfy the requirement of realtime for on-line weather route planning.