Global waypoint tracking control of underactuated ships under relaxed assumptions

This paper proposes a methodology to design a global waypoint tracking controller for underactuated ships, of which the mass and damping matrices are not assumed to be diagonal as often required in the literature. Our new result is facilitated by a lemma developed for a nonlinear interconnected system, several nonlinear coordinate transformations, a global exponential observer and utilizing the ship dynamic structure Full state-feedback control design is presented in details and output-feedback is also briefly addressed. Numerical simulations illustrate the soundness of the proposed solution.