Control of fully actuated ocean surface vessels using a class of feedforward approximators

In this brief, we consider the problem of tracking a desired trajectory for fully actuated ocean vessels, in the presence of uncertainties and unknown disturbances. The combination of approximation-based and domination design techniques allows us to handle time-varying disturbances, without the need for explicit knowledge of the bounds. Using backstepping and Lyapunov synthesis, the stable tracking controller is first designed for the full-state feedback case. Subsequently, the output feedback problem is tackled by employing a high-gain observer to estimate the unmeasurable states required by the stable tracking controller. Under the proposed control, semiglobal uniform boundedness of the closed-loop signals is guaranteed for both full-state and output feedback cases.