Stabilization Control of Underactuated Unmanned Surface Vessels Based on Backstepping and Lyapunov Direct Method

In this paper, a time-varying controller is proposed for the underactuated Unmanned Surface Vessels (USV) with non-diagonal inertia and damping matrices. By introducing a reference trajectory, the controller can guarantee global asymptotic convergence from any initial values at any moment. Firstly, with the method of global diffeomorphism equivalent and input transformation, the stabilization problem of underactuated USV can be transformed into the stabilization of two cascaded subsystems. Secondly, according to the characters of the cascaded subsystems, the stabilization problem can be reduced to the one of the second subsystem, a nonlinear time-varying controller is developed through backstepping and Lyapunov's methods, stability analysis proves that all the states can be globally regulated to the origin. Finally, simulation results demonstrate the effectiveness of the proposed control approach.