Ship-stopping algorithm utilizing VecTwin rudder system for automatic collision prevention

Abstract

In this study, an algorithm for automatic ship stopping in an emergency is developed utilizing a VecTwin rudder system. Timing the emergency stop and determining the stopping capability of the ship equipped with the VecTwin rudder system are critical elements of the proposed stopping algorithm. The dangerous area of collision (DAC) between the ship and other ships is calculated to determine ship emergency stop. The algorithm is constructed such that the ship stops automatically after DAC, which is calculated based on the navigation situation between the own ship and the surrounding other ships, enters the emergency stopping region (ESR). The stopping capability of the subject ship equipped with the VecTwin rudder system was confirmed by a free-running model experiment with ship speeds determined by analyzing actual operational data. To validate the developed algorithm, two collision risk scenarios were selected—coastal navigation and in-port navigation—and simulations and free-running model tests were conducted for each scenario. It was demonstrated that the emergency stop algorithm developed for ships equipped with the VecTwin rudder system can reliably avoid collisions automatically. In addition, it was also confirmed that a shorter stopping distance was achieved than in the case of crash astern emergency stopping.