The design of adaptive nonlinear controller for dynamic positioning system of ships

Considering slowly varying environmental external disturbances and their uncertainties, an adaptive nonlinear PID controller for the dynamic positioning system of ships is designed based on vectorial backstepping with integrator under unknown constant environmental disturbances. Using Lyapunov stability theory, it is proved that the resulting dynamic positioning control system of ships is uniformly globally stable. The proposed control law forces the ship´s position and orientation to globally asymptotically converge to its desired values. The simulation results for the supply ship verify the effectiveness of the proposed control law for dynamic positioning of ships.