Nonlinear adaptive fuzzy output-feedback controller design for dynamic positioning system of ships

This paper develops a nonlinear adaptive fuzzy output feedback controller for dynamic positioning (DP) system of ships in the presence of unmeasured states of ships, unknown dynamic model parameters, unknown time varying environment disturbances and input saturation. It is the first time that all the conditions above are simultaneously dealt with in the DP control design. By combining adaptive fuzzy system and auxiliary dynamic system, a control scheme with high-gain observer is developed via vectorial backstepping method. It is proved that the proposed nonlinear adaptive fuzzy output feedback controller can maintain the ship at desired position and heading with arbitrary accuracy, while guaranteeing the uniform ultimate boundedness of all closed loop signals in the DP system. Finally, simulations are carried on a supply ship to demonstrate the effectiveness of the proposed control approach.