Research On COLREGs-compliant Shipborne Autonomous Collision Avoidance System

Collision at sea is always the significant issue affecting the safety of ship navigation.The relevant research on ship collision avoidance involves various fileds.International Maritime Organization(IMO)has developed the international rules for maritime collision avoidance(COLREGs)to dictate the operational behavior of different ships during the encounter situations.With the continuous development of autonomous ships in recent years,the research on shipborne autonomous collision avoidance system(SACAS)has attracted extensive attention.Trajectory planning is the process to search the optimal collision-free trajectory in the obstacle environment with the full consideration of ship maneuvering constraints and COLREGs rules.This is the core function of shipborne autonomous collision avoidance system.Through the literature survey and overall review,the research focus of this paper is located on the development of fully-coupled trajectory planning algorithms to simultaneously satisfy the obstacle constraints,ship maneuvering constraints,COLREGs rules,the optimal trajectory search,and the real-time requirements.A complete autonomous collision avoidance system was developed and customized to a trimaran ship model.The simulation results and model testing results in various scenarios demonstrated the effectiveness,real-time capability,and advantages of the developed trajectory planner.It is valuable for both academic research and industry application.The novelty of the proposed algorithm lies in the following aspects.A fully-coupled deliberative planning algorithm is developed,which can simultaneously satisfy the ship maneuvering constraints,COLREGs rules,trajectory optimality,and the real-time requirements in the global planning.A fully-coupled reactive planning algorithm is developed,which can simultaneously satisfy the ship maneuvering constraints,COLREGs rules,trajectory optimality,and the real-time requirements in the local planning.A parallel architecture combining the fully-coupled deliberative planner and the fully coupled reactive planner is developed,which can guarantee the feasibility,effectiveness and superiority of the planned trajectory under various obstacle conditions.The on-water tests of a trimaran model equipped with a model-scale SACAS system are presented to demonstrate the effectiveness and efficiency of the propsed planning algorithm.The present work provides an important basis for subsequent research and future application.