A Method for Estimating Dynamic Collision Risk of Vessels Considering Spatial-temporal Adjacency

The catastrophe theory is used to propose a vessel collision risk calculation method considering spatial- temporal urgency to solve the limited applications of traditional risk-calculation methods in terms of ship collision in busy restricted waters. A model to calculate spatial urgency of vessel collision is proposed based on the numerical calculation of the superimposed area of the vessel domain. Then a model to calculate temporal urgency of vessel collision is also proposed considering vector relationships between relative position and relative speed of ships. Moreover, based on the catastrophe theory, a model to calculate collision risk of vessels is proposed, reflecting spatial-temporal urgency. The proposed models are validated by simulations, and compared with the models considering distance to the closest point of approach(DCPA), time to the closest point of approach(TCPA), and spatio- temporal distance-based collision risk assessment. The results show that the proposed vessel dynamic risk model in this work is more accurate in judging the collision risk, associated with the reflection of decreased changes in collision risk. This improvement avoids the drawback of a lacking description of nonlinear risk changes by other methods. The proposed model provides mariners with an accurate means to make decisions of vessel collision avoidance.