An integrated decision support system for ship collision avoidance

The ship encounter process is divided into the stages of free action, risk of collision, close-quarter, and immediate danger according to the four-stage theory of ship encounters. Current research on ship collision avoidance primarily focuses on the risk of collision stage, aiming to prevent ships from entering the close-quarter stage. However, various navigational equipment and environmental factors may cause ships to enter the close-quarter or immediate danger stages. Therefore, this paper establishes an integrated decision support system for the above stages to ensure that ships can handle all situations. First, the system includes a new collision risk detection module based on the ship domain model and the four-stage theory. Subsequently, in the collision avoidance strategy formulation module, two sets of avoidance strategies are established based on the convention on the COLREGs and the most effective avoidance principle for ships in different stages. Finally, in the avoidance action optimization module, a new fitness function is constructed based on ship maneuverability, and the sparrow search algorithm is introduced to solve for the optimal avoidance actions. The results demonstrate the capability of the decision support system presented in this paper to effectively avoid other ships in different stages of the encounter process.