Research On Ship Path Planning Based On Marine Disaster And Ship Operation Model

As an important part of global logistics,ocean transportation mainly provides maritime passenger and freight services.In recent years,with the development of international trade and the global economy,the number of ships has also increased,which increases the probability of ship collision to a certain extent.At the same time,frequent marine disasters will also disrupt the original navigation plan.It is of practical significance to design a ship path planning method that can be applied to complex sea conditions.This thesis studies the method of ship path planning in complex sea conditions from two aspects: global environment and local environment.The marine disaster model and the ship operation model are established respectively in the global and local environments,and the overall marine environment model is established by combining the time grid method.C++ and Open CV are used to process the map and design the path planning algorithm.In the global environment,a marine disaster model is established according to the characteristics of marine disasters,the marine disasters are represented in grids,the appropriate grid size is calculated and a reasonable path expansion method is selected,and then the time grid method is used to describe the marine environment and construct a global dynamic map..The operation model of the ship is established in the local environment,and the ship is represented by grid according to the operation model of the ship,and the sailing state of the ship is represented by a vector.Under the global environment,an improved Theta* algorithm based on slope range constraints and an improved time grid method with expanded grid element information are proposed,and the path is planned based on the marine disaster model.Aiming at the problem that the time complexity of Theta* algorithm is too high when expanding nodes,a method of using slope range constraints to replace line-of-sight inspection is proposed,and the slope range is used as a constraint condition for neighbor node expansion,which can reduce the complexity of line-of-sight inspection time for extended nodes.reduced to a constant order of magnitude.Aiming at the problems that the traditional time grid method cannot judge large-sized obstacles and the terrain restoration is inaccurate,it is proposed to introduce time interval and initial state parameters into the time grid information to ensure the accurate update of dynamic obstacles.The improved method is applied to the path planning in the global ocean environment,which has the characteristics of fast calculation speed,short navigation path and less unnecessary turning angles.Finally,the path planning strategy in the global environment is compared and verified by simulation,and the simulation verifies the efficiency and operability of the global planning strategy.In the local environment,the operation model of the ship is established and the collision avoidance strategy at sea is introduced,and the local path is planned by combining the improved Theta* algorithm based on the slope range constraint and the improved time grid method to expand the grid element information.According to the speed,size and turning radius of the ship,the navigation area of the ship is restricted from the two aspects of the ship field and the turning angle,so as to establish the operation model of the ship to ensure the operability and safety of the ship’s navigation.The collision avoidance strategy in the local environment of the ship is introduced,and the three encounter situations of the ship’s overtaking,confrontation and crossencounter are considered according to the implementation rules of international maritime affairs,so as to ensure the safety of the ship’s encounter.The application of the local path planning strategy can ensure the safety of navigation,and the final planned path also meets the operational requirements.After comparative simulation experiments,the local path planning method has the advantages of strong operability,short path and high security.