Collision Avoidance for Underactuated Surface Vehicles in the Presence of Ocean Currents

This paper considers the problem of collision avoidance for surface vehicles moving under the influence of ocean currents. The vehicles we consider have underactuated dynamics, where the vehicle cannot directly control its lateral motion, which is a common trait of marine vehicles. We propose a reactive algorithm where the vehicle dynamics, including its underactuation and the effects of an ocean current disturbance, are handled directly in the avoidance strategy. Moreover, the algorithm only requires a limited amount of information about the obstacle and is proven to guarantee collision avoidance, as well as the completion of a nominal goal, under explicitly derived conditions. The theory is validated by simulations.