Guaranteed Safe States in Speed Space for Ships Collision Avoidance Problem

Abstract

The article has considered approach to ships collision avoidance problem for infinite time horizon in unpredictable navigation environment on the basis of guaranteed safe states in speed space. The possible collisions areas are determined on the basis of the reachable sets of target vessels in the speed space. By avoiding getting into the possible collisions area of each target vessel, the controlled vessel prevents any possible collision, while not having explicit information about the expected trajectories of the target vessels. The safety of navigation is achieved by a combination of reachable sets as functions of time for target vessels, taking into account their dynamic capabilities and the representation of sets in speed space. The control option, which is outside the reachable set of the target vessel in the speed space, is guaranteed to prevent a collision even under conditions of unpredictable motion of the target vessel. On the basis of the target vessels reachable sets in speed space the guaranteed safe states of controlled vessel are defined. Recommendations for practical use have been given. Performed researches contribute to the improvement of the ship’s handling methods.