A novel collision risk assessment method with spatiotemporal and COLREGs constraints

A collision risk assessment method is proposed that combines spatial and temporal constraints with regulatory requirements. The restricted velocity set is first obtained using the velocity obstacles method and the ship domain model, and is then refined using the closest point of approach method, incorporating compliance considerations derived from the International Regulations for Preventing Collisions at Sea (COLREGs). These sets are then integrated, and their ratio to the total velocity set defines the time-varying collision risk parameter. To capture the dynamic characteristics of encounters, a temporal parameter based on the closest point of approach is incorporated. Finally, a ship-motion model and a direct adaptive control algorithm are introduced to realise collision-avoidance manoeuvres. Simulation studies demonstrate that the proposed method improves the clarity and effectiveness of risk evaluation relative to existing approaches and reveals differences between heading-based and course-based formulations. • A collision risk assessment method is proposed that combines spatial and temporal constraints with regulatory requirements. • The restricted velocity set is first obtained using the velocity obstacles method and the ship domain model. • It is then refined using the closest point of approach method, incorporating compliance with COLREG. • These sets are integrated, and their ratio to the total velocity defines the time-varying collision risk. • Simulation studies demonstrate that the proposed method improves the clarity and effectiveness of risk evaluation.