A Voronoi-diagram-based dynamic path-planning system for underactuated marine vessels

The main contribution of this paper is the development of a rapid, dynamic path-planning system for 3-DOF marine surface vessels navigating in environments where other marine vehicles might be operating too. The method is based on the Voronoi diagram and generates the initial path while ensuring that clearance constraints are satisfied with respect to both land and shallow waters. Fermat's Spiral (FS) segments are used to connect successive straight lines, hence, resulting in curvature-continuous paths that are rapidly computed. When a ship is detected, the range of its position during a given time frame is estimated, and the path-planning system produces in real time a new safe and smooth path. The International Regulations for Preventing Collisions at Sea (COLREG) are taken into account in the replanning procedure. An indirect adaptive Line-Of-Sight (LOS) guidance algorithm from the existing literature is implemented to ensure the underactuated vessel will counteract the effects of unknown environmental forces, such as ocean currents, while converging to the safe path. Simulations show the effectiveness of the proposed approach.