Research On Optimization Of Offshore Ship Path Based On A-star Algorithm

With the proposal of China’s maritime power strategy,China gradually attaches importance to the development of Marine economy and strives to improve the benefits of Marine economy.Ship transportation is an important part of transportation.Compared with land transportation,ship transportation has advantages such as strong transportation capacity,low cost and wide range.For ships sailing on international routes,navigation obstacles can only be followed along the established route,but compared with the far sea,the environment is more complex and the path planning is more difficult.It is of great application value to provide a safe and efficient route reference for ships sailing near the sea.A~* algorithm is the most effective method to search the shortest path under the condition of known traffic environment information.However,ship navigation obviously cannot only consider the shortest distance,but pursues the shorter distance under the premise of ensuring navigable safety.This paper gives full consideration to the safety requirements of ship navigation and combines the characteristics of offshore environment to design A safety model and improve the A~* algorithm,so as to provide an effective safe path for ship navigation.The main research work of this paper is as follows:1.Modeling of offshore navigation environment.This paper summarizes the navigation environment in coastal areas,analyzes the types and characteristics of navigable obstacles based on the electronic chart,and puts forward the chart processing methods: the FCM fuzzy clustering algorithm is introduced to extract the chart elements,and the HSV color gamut is used to achieve binary processing of the chart.To facilitate the implementation of the improved A * algorithm,using the grid method on the chart environment modeling,storage information chart elements and proposes the navigation security model,introducing the danger zone,the dangerous area and safety area,the safety of the single obstacle with many obstacles design scheme model,and makes the division of grid threat to quantify the location of the navigation safety.2.Optimization based on standard A~* algorithm.Based on the standard A * algorithm,combined with the offshore ship navigation requirements in terms of the following three algorithm optimization:(1)optimize the search function,referring to the security model of design,on the coast,islands,reefs,cross-sea bridge,sunken ships,shallow water,such as static factors,and the wind,wave A quantitative analysis of natural factors,into the path of the heuristic function to make the ship planning can choose the safest path,considering the above factors of dynamic weight coefficient to adjust the g(n)and the value of h(n)heuristic function realizes the search efficiency and the balance of the search results;(2)The neighborhood search was optimized,and the 8 neighborhood search of the standard A~* algorithm was expanded to24 neighborhood search,which effectively solved the problems of too many turning times and uneven path existing in the planned path.(3)Optimize the search efficiency,introduce the twoway search and use the target point dynamic update,ensure the convergence of the starting point and the end point search,use the minimum binary heap to replace the traditional linked list to realize the OPEN list,design the minimum binary heap operation corresponding to the OPEN list insertion and deletion,improve the efficiency of path planning.3.Experiment and result analysis.The experimental evaluation indexes were designed as safety value,path length,number of turning points and algorithm execution time.The simulation chart was used to conduct intra-group and out-group comparison tests,in which the three optimization points of the algorithm were respectively compared within the group to verify the effectiveness one by one.Compared with similar algorithms,the superiority of the algorithm is verified.Through theoretical analysis and experimental verification,the three-point optimization introduced by A-STAR algorithm in this paper is effective.The optimized algorithm has short path distance,few turning points and smooth path planning,good search efficiency and path planning time within A reasonable range.It can provide a feasible route for ships sailing in the offshore area,avoid static obstacles and local high wind and wave areas,and fully guarantee navigation safety,which has strong application value.