Study On Ship Collision Avoidance Decision-making Based On Quaternion Ship Domain And Fuzzy Logic

With the implementation of the"21^st-Century Maritime Silk Road"strategy,waterway transportation still plays an important role in international logistics and trade,which has led to a continuous increase in the density of maritime ship traffic,and attracts considerable attention to the risk of ship collisions.At the same time,ship collision accident is also one of the most main types in accidents that cause casualties at sea,accounting for a large proportion in maritime traffic accidents.Based on the above background,in order to reduce the probability of ship collisions due to human factors,two-ship and multi-ship collision avoidance are selected as the research object in open water,this study focuses on the specific problems of ship encounter identification,collision risk calculation,and collision avoidance decision.The collision risk calculation and collision avoidance decision-making for two-ship and multi-ship encounter scenarios are realized.The detailed studies are listed as follows.（1）A model for the identification of ship encounter situations considering the target ship’s course and speed is developed in sight of one another.On the basis of the analysis of the ship’s collision avoidance process and the identification of traditional encounter situations,the encounter recognition model for head-on,overtaking,and crossing situation is developed based on the basic constraints of the International Regulations for Preventing Collisions at Sea（hereinafter referred to as"the regulation"）and ordinary practice of seamen,to clarify the responsibility of avoidance between ships.（2）A ship collision risk calculation model based on the quaternion dynamic ship domain and fuzzy logic is proposed.Based on the analysis of the geometric principles of ship collision avoidance,a ship collision risk calculation model is proposed and the distance to closest point of approach,time to closest point of approach,relative bearing,relative distance,and ship speed ratio are taken as the main parameter indicators of the model.In order to extend the applicability and improve computational accuracy of the model,the quaternion dynamic ship domain model is proposed to be introduced into the conventional model as the boundary divider of the distance to closest point of approach affiliation functions.The improved ship collision risk calculation model takes into account the effect of ship length,and real-time speed on the minimum safe distance of approach between ships.Experimentally validate the effectiveness of the improved model to provide a reliable basis for ship collision avoidance decisions.（3）An improvement strategy for ship collision avoidance decision model based on linear expansion algorithm is proposed.The two-ship encounter and multi-ship encounter models are developed for ship collision risk and collision avoidance decisions,and three encounter situations of two-ship and four encounter scenarios of multi-ship are set up for experimental verification.By comparing and analyzing the relationship between the change in parameters of collision risk between ships,the collision avoidance situation,and the change in range during avoidance.It is verified that the proposed method can accurately calculate the collision risk between ships,and safely avoid the target ship,which can provide good auxiliary decision-making support for the Officer of Watch.In sum,in order to satisfy the need for navigation safety and security and intelligent collision avoidance decisions,this study has developed the research of the open water ship collision risk calculation and collision avoidance decision-making model,which have great theoretical value and practical significance to ensure the safe,and efficient navigation of ships and promote the further development of ship intelligent collision avoidance decision-making.