A unified concept for controlling a marine surface vessel through the entire speed envelope

This paper addresses the problem of creating a controller structure for the automatic control of a marine surface vessel through its entire speed regime without resorting to heuristics and switching between fundamentally different controllers. Hence, a single controller structure is proposed for the purpose. Its core is a nonlinear, model-based velocity and heading controller which relies on a key guidance-based path following concept necessary to ensure geometric path convergence. The scheme renders all regular paths feasible, and ensures that a vessel which is fully actuated at low speeds, but becomes underactuated at high speeds, is able to converge to and follow a desired geometric path independent of the current vessel speed