Nonlinear Adaptive Control of Ship Dynamic Positioning Based on Single Parameter Learning

This paper deals with the problem of controlling the dynamic positioning of a ship in the presence of unknown time-varying disturbances, model uncertainty and input saturation. First, the uncertain model parameters and unknown time-varying disturbances are combined to form a composite uncertain vector, and this composite uncertain vector is transformed into a single-parameter linear parametric form by inequality deflation. Second, an adaptive backstepping design method is used to design an adaptive dynamic positioning control law, and the unknown single parameter is estimated online using the adaptive law. Finally, the input saturation problem is handled by an auxiliary dynamic system. It is proved by Lyapunov stability theorem that the designed dynamic positioning control law can guarantee that all signals in the closed-loop control system are consistent and eventually bounded. The simulation results show that the designed control system can effectively achieve the ship dynamic positioning.