Research On The Path Planning Algorithm Of Surface Unmanned Vehicle

With the gradual scarcity of land resources,a large number of unexplored marine resources have received widespread attention from various countries.At the same time,the ocean is a natural security barrier for coastal countries.So ensuring the security of the ocean is ensuring the security of the land.Therefore,the importance of the ocean in the national development strategy is self-evident.As an intelligent equipment capable of autonomously performing a variety of tasks on the sea,unmanned surface vessel(USV)have been widely used in military and civilian life.Due to the complexity of the marine environment,the path planning system has become an essential part of the USV intelligent system.The path planning system mainly includes two parts: global path planning and local path planning.Global path planning,also known as static path planning,enables USV to avoid static obstacles.Local path planning,also known as dynamic path planning,enables USV to avoid static and dynamic obstacles in the surrounding environment.In order to improve the navigation performance of the USV on the premise of ensuring the safety of it,the following researches are done on the path planning of the USV:(1)Global path planning: Use the grid method to model the marine environment.study the principles and steps of the A * algorithm,and propose two improvements.One is to optimize the OPEN list using the minimum heap structure,and the other is Extend one-way search to two-way search.Under the same conditions,the traditional A * algorithm and the improved A * algorithm were simulated and compared.The results show that the improved A * algorithm has a 60% reduction in search time and a 25% reduction in node list space compared to the traditional A * algorithm.(2)Local path planning: the application of dynamic window method in the local path planning of USV is deeply studied and analyzed.The weight coefficient considering the sea state level is added into the evaluation function,so that when the sea state level is higher,the weight of speed will decrease and the weight of safe distance will increase.In the case of static and dynamic obstacles,the simulation is carried out to verify the local obstacle avoidance ability of dynamic window method.(3)Hybrid path planning: In order to solve the defects of A * algorithm and dynamic window method,a hybrid path planning algorithm based on A * and dynamic window method is proposed.First,the A * algorithm is used to obtain the global path to generate a local target point.With the continuous updating of the local target point,the USV uses the dynamic window method to sail to the global target point to complete the path search.Simulations show that,Compared with the A * algorithm,the hybrid algorithm shortens the path length by 10% and reduces the turning point of the path by 67%.the performance of the proposed hybrid path planning algorithm is better than the performance of the two algorithms alone,and an correct and smooth secure path is generated from the starting point to the target point.