A unified control concept for autonomous underwater vehicles

This paper addresses the problem of creating a controller structure for the automatic control of autonomous underwater vehicles (AUVs) through their entire non-zero speed regimes, without resorting to switching between structurally different controllers. A single controller structure is proposed for the purpose, whose core is a nonlinear, model-based velocity and attitude controller that 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 an AUV 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 vehicle speed