A novel arena-based collision avoidance behavior analysis method for autonomous ships

Ship automatic collision avoidance is an emerging core technology for achieving assisted and even autonomous navigation with human-like decisions. Ship collision avoidance maneuvers must be implemented within their lifecycle, between the earliest and latest effective points. Investigating the latest point is crucial for clarifying the mechanism of ship collision avoidance, helping to reduce unnecessary early maneuvers. To address this issue, this study proposes a novel approach to study ship collision avoidance behaviors mechanism by introducing the concept of ship arena. We define the arena as the latest boundary for collision avoidance actions to prevent the infringement on the ship domain. By integrating the ship domain with the Velocity Obstacle (VO) method, we propose a collision risk detection method anchored in the concept of a collision zone. This method enables the calculation of the latest collision avoidance distances, i.e., the arena, for ships within this area. We develop a ship arena generation method for specific encounter scenarios and validate our proposed approaches and strategies through simulations and real Automatic Identification System (AIS) data verification. Our results show that the proposed arena method provides a robust framework for assessing collision avoidance behaviors, determining maneuver timing, and supporting decision-making processes in maritime navigation.