The Research On Mode-free Control Strategy Of Ship Rudder/Fin Joint System

The ship sailing on the sea is inevitably affected by the wind,waves and other factors;in this case,rolling,swaying,yawing and pitching will happen.The severe shaking can seriously affect the safety and stability of the ship at sea.The rudder and fin joint system is considered to be able to control the course precision with the steering gear and to reduce the stabilization of the fin stabilizer.Therefore,the stability,maneuverability,safety and comfort of the crew are improved.This thesis focuses on the establishment of a mathematical model for four-freedom ship motion,and the model-free control strategy of combined rudders and fins system is designed.Firstly,according to Newtonian dynamical momentum theorem and momentum moment theorem,a four-degree-of-freedom nonlinear mathematical model for ship motion is constructed.and it was subjected to a convolution test and a zigzag maneuvering test simulation.Comparing with the data given in relevant literature and ship maneuverability standards,the correctness and reliability of the ship model built in this thesis are proved.Then,according to the linear mathematical model of the Conolly ship,In this paper,designed a model free adaptive anti-rolling controller,and through the simulation study and comparison with PID control,it shows that MFAC shows strong robustness in the lower frequency wave disturbance than PID control.In the rudder and fin joint system,course system design to the scale after loop feedback within subduer of improved MFAC heading controller and the nonlinear rolling motion system of MFAC anti-rolling controller,in the process of ensuring the accuracy of the ship's heading control,it can effectively reduce roll,and a simulation study was carried out.Compared with PID control,MFAC has the advantages of less adjustable parameters,simple parameter adjustment,more convenient implementation,and more adaptive ability of MFAC in course control.In the high sea condition,MFAC shows stronger robustness and adaptability in anti-rolling control.In the end,the design and simulation study of the ship rolling linear model is carried out,The results show that the anti-rolling effect is better than PID control.On this basis,for the rudder and fin joint system,the designed ADRC strategy-based controller can not only accurately control the heading but also effectively suppress the ship.To simplify the design structure of ADRC,reduce ADRC regulation parameters and design the LADRC course controller for the rudder fin joint system.Through the simulation study,LADRC has the course control quality which is not lost to PID.At the same time,the ADRC stabilization controller is designed,and the simulation results discover that,Whatever the sea condition,the anti-rolling effect of ADRC in the nonlinear rolling motion is better than PID control,and the robustness is stronger.