Research On Real-time Dynamic Collision Avoidance Method Of High-speed Watercraft

With the increasing frequency of maritime trade,the competition among countries in the maritime neighborhood is expanding day by day,the role of intelligent unmanned boat will be more and more important,and the research on intelligent unmanned boat at home and abroad has been paid more and more attention,so that unmanned boat has more intelligent and economic characteristics will be the focus of future research.In the research of unmanned boat,the research of dynamic collision avoidance of high-speed surface unmanned boat will be one of the important links of intelligent research of surface unmanned boat.In this paper,the high-speed surface unmanned vehicle is taken as the research object,aiming at the dynamic collision avoidance behavior of the dynamic obstacles during the navigation of the unmanned vehicle.According to the real-time characteristics of high-speed craft,two algorithms,geometric collision avoidance algorithm and dynamic window algorithm,are selected as the core algorithm of dynamic collision avoidance.The collision avoidance methods based on these two algorithms are studied.For the geometric collision avoidance algorithm,the comprehensive performance of obstacle avoidance time,route deviation degree and return safety are fully considered.Firstly,the basic principle of geometric collision avoidance algorithm is introduced.According to the different speed,the dynamic collision avoidance of unmanned boat is divided into two specific collision avoidance modes: collision avoidance of high-speed boat and collision avoidance of low-speed boat.When the comprehensive risk CRI is greater than 0.5,the unmanned boat begins to conduct collision avoidance maneuver.According to the relative motion information of the unmanned boat and the target ship,the safe course range of the unmanned boat can be obtained through theoretical analysis and calculation.Based on the safe course range range range,this paper puts forward three concepts of the shortest collision avoidance time,the minimum deviation from the original route distance,and the safety of the return voyage.Combined with the international maritime collision avoidance rules,the dynamic collision avoidance behavior of the unmanned boat can achieve the collision avoidance process And safe navigation in the process of resuming navigation,and taking into account the optimal economic performance of collision avoidance navigation.For the dynamic window method,it focuses on improving the accuracy,navigation economy and arrival stability of the dynamic window.In the process of dynamic collision avoidance,the dynamic window method can generate the dynamic window of speed and heading rotation angle in real time.In order to facilitate the research and calculation,the speed is discretized in the dynamic window.After sampling,the predicted route is obtained according to the discrete speed and heading.In the evaluation function,the azimuth between the unmanned boat and the waypoint,the distance between the unmanned boat and the obstacle,and the speed are evaluated comprehensively to get the optimal predicted route.In this paper,we will further optimize the dynamic window by fusing the velocity obstacle method,so that the improved dynamic window can have better collision avoidance effect.In addition,in order to make the unmanned boat reach the waypoint at a stable speed and keep itself stable,we will increase the distance threshold sad of the smooth arrival,and improve the speed change of the unmanned boat by using the distance threshold SSD of the algorithm fusion.The simulation results of two collision avoidance methods show that the geometric collision avoidance method can achieve the comprehensive optimization of safety performance and economic performance in the dynamic collision avoidance process,and the combination of the international maritime collision avoidance rules has good real-time performance,which is a good collision avoidance method.However,it is not suitable for dynamic collision avoidance in the presence of static obstacles.Because of the real-time update of the dynamic window,the improved dynamic window method has a high real-time performance,which has a good collision avoidance effect on dynamic obstacles,and improves the speed of collision avoidance decision-making and its own stability.The improved dynamic window collision avoidance method in this paper has a good effect on dynamic collision avoidance,but its economic performance is not optimal.