Finite time control for line path following of underactuated surface vessels

Considering the model parametric uncertainties and time-varying disturbances induced by wave, wind, and ocean-current in the trajectory tracking control of a 3 degree-of-freedom underactuated surface vessel (USV), a novel nonlinear finite time control law is designed, in view of robustness of the finite time control in anti system uncertainties and environmental disturbances. The path following problem of the underactuated system is transformed into stabilization problem of the nonlinear system by simplifying analysis of the USV system. The disturbance observer is designed to compensate control by observing unknown disturbance in real-time, which effectively restrains the disturbances of wind, wave and flow time-varying. The finite time control combined backstepping law is proposed, which ensures the error uniformly bounded by Lyapunov stability theorem, and improves robustness and convergence of system. Simulation results are provided to demonstrate effectiveness of the method.