He, Y.; Huang, L.; Xiong, Y., and Hu,W., 2015. The research of ship ACA actions at different stages on head-on situation based on CRI and COLREGS.

In order to study the Automatic Collision-Avoidance (ACA) actions of vessels in head-on situation in accordance with rules of International Regulation for Preventing Collision at Sea (COLREGS 72) and ordinary practice of seaman, stags of vessel's meeting process were separated by Collision Risk Index (CRI) and Time to Immediate Danger (TID). The reason to correct Collision-Avoidance (CA) actions at different stages are different. CRI and TID were derived from defined Situation Elements (SE) in head -on situation. Then computing models of them and ACA actions at different stages were presented. The basis of this research is the center moved ship's elliptical domain theories and MMG three-free dimensional digital model which is calculated by ship's hydrodynamic equations. The following is proved by simulations: The mathematic models presented ensure rapid and reliable convergence of SE computing; new CRI model is much more in line with the thinking process of navigators and practice at sea than before; ACA actions in accordance with COLREGS rules and ordinary practice of seaman, can be produced by program. The research may make big improvement to the final achievement of ACA of ship in head-on situation.