Sliding mode observer design for ship dynamic positioning systems

Dynamically positioned vessels are widely used in the exploration of offshore oilfield. State estimation is an important feature of a dynamic positioning system. A sliding mode observer is proposed for ship dynamic positioning systems in the presence of unknown external disturbances by using sliding mode observer structural principle. The proposed sliding mode observer can estimate positions and velocities of ships. The observer´s error dynamics is proven globally asymptotically stable. Finally, the simulation results on a supply ship show the effectiveness of the sliding mode observer for ship dynamic positioning systems.