On evolutionary computing in multi-ship trajectory planning

The paper presents the updated version of Evolutionary Sets of Safe Ship Trajectories: a method which applies evolutionary algorithms and some of the assumptions of game theory to solving ship encounter situations. For given positions and motion parameters of the ships, the method finds a near optimal set of safe trajectories of all ships involved in an encounter. The method works in real time and the solutions must be returned within one minute, which enforces speeding up the optimization process. During the development of the method we have tested extensively various formulas for fitness function, problem-dedicated specialized operators as well as methods of selection. In the course of this research it turned out that some of the classic evolutionary mechanisms had to be modified for better performance, which included the order of some operations. The results of the adaptation process are presented here. The paper includes explicit description of all evolutionary mechanisms used and accentuates the research on improving the optimization process by adjusting evolutionary mechanisms to the problem.