Design of Dynamic Surface Controller Based on Nonlinear Observer for Ship Dynamic Positioning System

Considering that vessels need to position more quickly and accurately in complex environments, a control system combining a nonlinear observer and dynamic surface controller is proposed. In order to simplify calculation and increase practicality in engineering, dynamic surface control technology is introduced. For getting a more accurate velocity, a nonlinear passive observer can be introduced to estimate them which is impossible to measure accurately. Stability is proved by selecting an appropriate Lyapunov function and the appropriate parameters are chosen to ensure all signals are uniformly bounded. The simulation results show that the ship's center of gravity can reach and stabilize in the desired position within a short time. Therefore, the designed control law is effective.