Study On Ship Maneuvering And Rolling Prediction And Course-Keeping Control In Waves

Ship maneuvering in waves and its control has always been a research focus of the ship sailing and control theorists for the purpose of safety at sea and economic requirements. This paper presents research work on ship maneuverability from hydrodynamic model and motion response model respectively based on this engineering background.In the aspect of hydrodynamic model, a coupling 4-DOF ship mathematic model considering maneuvering motion of sway, surge, yaw and roll is established based on MMG model. The roll motion of sea-keeping is added into the maneuvering function with the help of unified theory. Numerical prediction of ship maneuvering and rolling in waves is conducted by adding the wave force into the coupling model when the wave force modeling is completed. The numerical results are compared with Free-running model test, which shows that the maneuverability and rolling results of the coupling model are credible. Ship maneuvering and rolling performance and rudder efficiency are analyzed in different conditions after the model is validated. Steering recommendations are also given according to the results.In the aspect of motion response model, the nonlinear steering-turning response model is derived by the maneuvering function. There are three difficulties in the course-keeping control problem: motion nonlinearity, model uncertainty, machine executing, which are considered respectively by parameters perturbation and disturbance modeling, adaptive fuzzy controller design and steering servo system and the physical constraints of the filter design. The control results of ship course-keeping in different ideal course, parameter perturbation and external disturbance are carried out with the helpof Simulink toolbox. The results validate the excellent stability, adaptability and robustness of the fuzzy controller, the robustness is also shown by applying the controller to different ship in course-keeping problem.