“…Most papers considering nonlinear motion control for underactuated marine surface vessels typically use some variant of the model (10)-(11), and assume that the model parameters are either perfectly known or known with only a small degree of uncertainty, see, e.g., (Breivik and Fossen, 2004), (Børhaug and Pettersen, 2005), (Do and Pan, 2006), (Fredriksen and Pettersen, 2006), and (Aguiar and Hespanha, 2007). In practice, it can be quite hard to obtain the parameter values required to populate (11), especially with regard to the hydrodynamic damping matrix.…”