Output redefinition dynamic inverse trajectory tracking control of underactuated surface vessels with external disturbance

In this paper, a robust trajectory tracking control law is proposed for underactuated surface vessels (USVs) in the presence of unknown time-varying disturbances. A disturbance observer (DO) is firstly designed to provide the estimates of unknown time-varying disturbances and used for feedforward compensation control. Then, the robust trajectory tracking control law is proposed by combining the DO into the output redefinition dynamic inverse (ORDI) technique. It is proved that the designed control law can force the ship to track the desired trajectory. Simulation results on an underactuated model ship verify the effectiveness of the proposed control law.