Path-following control problem for maritime autonomous surface ships (MASS) in adverse weather conditions at low speeds

With the increasing popularity of autonomous vehicles, the maritime industry has focused on the development of Maritime Autonomous Surface Ships (MASS). An essential aspect of autonomous ships is their ability to follow a predetermined path at sea, as deviations from this path can jeopardize navigational safety, leading to accidents like collisions and grounding incidents. Therefore, ensuring that autonomous ships can safely navigate by following predefined routes is of utmost importance. Simultaneously, the implementation of the Energy Efficiency Design Index (EEDI) by the International Maritime Organization (IMO) has raised interest in a ship's manoeuvring performance in adverse sea conditions, aiming to reduce greenhouse gas emissions. The Marine Environment Protection Committee (MEPC) has provided guidelines to determine the minimum propulsion power required to maintain ship manoeuvrability in adverse conditions. This study investigates the pathfollowing performance of a ship operating at low forward speeds in adverse weather conditions using a freerunning Computational Fluid Dynamics (CFD) model, enabling accurate prediction of manoeuvring behaviour. The numerical results emphasise the significance of low forward speeds in enabling a ship to follow a predetermined route, offering valuable insights into path-following performance with minimum propulsion power in adverse weather. The study reveals that increasing propulsive power reduces deviations from the predetermined route when the ship encounters bow and beam waves. However, the impact of propulsion power on deviation is negligible in quartering waves during path-following control. This research contributes to improving guidelines for minimum ship powering, ensuring safe autonomous navigation in adverse weather conditions.