Nonsingular Serret-Frenet based path following control for an underactuated surface vessel

In this paper we develop a new control law to steer an underactuated surface vessel along a predefined path at a constant forward speed controlled by the main thruster system. The methodology is based on the Serret-Frenet formulation to represent the ship kinematics in terms of path parameters, which allows for convenient definition of cross and along track error. Furthermore, our approach for path following overcomes the stringent initial condition constraints. This paper also addresses the path following with environmental disturbances induced by wave, wind, and ocean-current. The proposed controller is designed based on the Lyapunov direct method and backstepping technique. The closed loop path following errors is proven to be uniform ultimate bounded. Results are demonstrated by high fidelity simulation.