AN AUTOMATIC COLLISION AVOIDANCE AND ROUTE GENERATING ALGORITHM FOR SHIPS BASED ON FIELD MODEL

Abstract

This study used a velocity potential field approach to develop an automatic collision avoidance system and a route-generating algorithm for merchant ships. The system includes course changing and track-keeping modes. The system based on the velocity potential of source/vortex and dipole flow theory in fluid dynamics. The course-changing mode creates a source/vortex flow vector to guide the ship away from various obstacles. The track-keeping mode generates a dipole flow field to steer the ship back to the desired course. An algorithm for collision avoidance maneuvers is implemented by using the real-time data of DCPA, TCPA, and bearing angle based on the results of maneuver simulation. Collision prevention regulations and international navigational rules are incorporated into the algorithm. The velocity potential field method is straightforward and very simple to implement; it avoids the problem of deadlock that hampers artificial potential methods and is suitable for the real-time path planning of complex static obstacles or ship encounter situations. The method has been applied to some typical test cases, including head-on, over-take, and crossing encounter situations with ships. The results prove that the proposed method is useful in finding safe paths for ships in encounter situations.