Fuzzy Decision on Optimal Collision Avoidance Measures for Ships in Vessel Traffic Service

This article proposes a new collision avoidance decision method for ships, allowing ships at risk of collision to take timely collision avoidance measures to ensure safe passage. Through vessel traffic service (VTS) collision alert system, an analysis can be made for the probability of a ship collision and an early warning can be issued. For ships in potential collision danger, the proposed method will use Microsoft Visual Studio to establish a knowledge base of international regulations for preventing collisions at sea. Thus, based on an analysis of the situation when encountering other ships, the knowledge base will suggest an appropriate avoidance technique and use a fuzzy monitoring system, propose a novel collision danger domain that forbids entering for give-way ship. Considering the required advance for ship turning, the fuzzy monitoring system will suggest the optimal rudder steering procedure for the give-way ship, allow the ship to avoid collision and ensure navigation safety. The avoidance action taken by the ship does not consider reducing speed, instead focuses only on rudder steering. The system also integrates VTS/automatic identification system (AIS)/marine geographic information system (MGIS) by using MGIS as an AIS imaging system to facilitate the optimal decision for ship collision avoidance and determine the input linguistic variables for the fuzzy logic theory via an analytical hierarchy process. The proposed method can enhance the VTS operator’s decision-making abilities for collision avoidance by providing a fuzzy monitoring system.