A trajectory tracking control method for underactuated surface ships

We proposed a nonlinear control method for trajectory tracking of underactuated surface ship. The nonlinear hydrodynamic damp and sway velocity are included in the ship model, which can stand for high speed and low speed of the ship. In kinematics loop the reference yaw angle and the reference speed are given. The nonlinear controller is designed in dynamics loop to make the error variables asymptotically stable. The stability of the closed-loop system is analyzed by using Lyapunov theory. Simulation results illustrate the effectiveness of the proposed control method.