ABSTRACT
Among maritime accidents, collision between ships is one of the most common types of accident sometimes causing extensive economic loss and serious casualties. In fact, a lot of collisions happen because the navigators of the ships misunderstand each other’s intention. Consequently, communication and coordination between ships is of great importance to avoid collisions, especially under multi-ship encounter situations. In this paper, a distributed anti-collision procedure for use in a multi-ship encounter situation is designed. Each ship makes decisions based on its own observations of other ships’ behaviors or actions to keep clear of all the ships that it should give way to. The trajectory planning algorithm complies with the International Regulations for Preventing Collision at Sea (COLREGs). The actions of each ship are evaluated separately at first to assess the effectiveness of the trajectory planning algorithm. Then the anti-collision performance is evaluated as a whole. The results show that there are conflicts and inconsistences which may result in a collision, even though the trajectory planning algorithm is effective when considering each ship on its own. Therefore, communication among ships during anti-collision decision making is indispensable in some circumstances.
