Numerical simulation-based collision risk assessment of autonomous underwater vehicles during launch and recovery

This paper presents a model for assessing collision risk during the launch and recovery (L&R) of Autonomous Underwater Vehicles (AUVs), aiming to provide auxiliary information to operators. The study focuses on a specific type of AUV side crane Launch and Recovery System (LARS), investigating the nonlinear coupling interactions among the ship, cable, and AUV motion under irregular wave conditions. A dynamic model of LARS is developed, considering factors such as seawater resistance and cable length variations. The motion of the AUV under different sea conditions is calculated and analyzed. A collision-probability estimation model for L&R is formulated from extrapolated AUV dynamic responses. Based on the Bernoulli trial principle, the collision probability is calculated through batch simulation, and the half-width of the confidence interval and the chi-square statistic are computed to assess the accuracy and stability of the results. Finally, the collision probabilities of different dynamic models of the LARS are analyzed and compared, and a risk assessment is conducted in accordance with DNVGL-RP-N103. The results provide a basis for evaluating the feasibility of AUV L&R operations under different sea conditions. This basis serves as auxiliary information for LARS operators of AUV, helping to make decisions during operation.