Algorithms for determining deadlines and COLREG-compliant manoeuvres for safe navigation in multi-ship scenarios using velocity areas

Abstract This study is positioned within the framework of multi-ship collision avoidance. It presents algorithms developed for the automatic identification of risk-free areas and the manoeuvres required to ensure safe navigation in multi-ship encounters in high seas. Inputs for them are data received from an AIS system and data calculated for each target and some predefined safety parameters and the pertinent COLREGs to be applied. These algorithms emulate the sequence of assessments and decisions typically undertaken by the Officers in charge Of a Navigational Watch (OONWs) to navigate safely towards the next waypoint in multi-ship encounter scenarios. Using polar graphs for velocity vectors, and by assigning weights to individual cells within velocity areas, the developed algorithms allow for the automatic determination of the most appropriate manoeuvre, while ensuring compliance with COLREGs. The resulting output is suitable for integration into autonomous navigation systems.