Semi-global output feedback tracking control for fully actuated ships

An output feedback trajectory tracking controller for a kind of 3 degrees of freedom (DOF) ship motion nonlinear model is designed. The closed-loop control system is proven to be uniformly semi-globally exponential stable with a separate stability result for the observer by applying nonlinear cascaded system theory. Simulation results on a model ship, Cybership II, are presented to validate the proposed control scheme.