Dynamic positioning controller based on unified model in extreme seas

The contributions of this paper are in two main areas. Firstly, Considering the linear superposition of Low-frequency and Wave-frequency models is not applied to the extreme seas, this paper researched the unified seakeeping-manoeuvering model in extreme seas. Secondly, to deal with the model uncertainties of ship model caused by the fluid memory effect, an adaptive backstepping controller is proposed. Acceleration feedback (AFB) is applied in the controller to increase the performance of ship in extreme conditions. A simulation example is given to demonstrate the effectiveness of the proposed method. © 2013 Binary Information Press.