Research On The Reduction Of Longitudinal Motion Of Ships By Controllable Fins

Ships longitudinal vertical shaking movement, especially the swing motion ,have great harm on the waves sailing ship, so after the ship rolling problem is resolved, the vertical movement of the ship sway became the most problems to be solved. With advances in technology, ship design has also made considerable progress; there have been many high-performance boats, such as SWATH ship, hydrofoils, etc., with good seakeeping. But many other aspects such as economic was taken into account, most of the existing ordinary boat could not have been replaced by high-performance boats, improvements to existing vessels to change their Seaworthiness and seakeeping is particularly important. When boat affected by disturbance of the waves,the ship will be accompanied by swaying motions transverse, longitudinal movement sway acceleration, thereby increasing the incidence of seasickness , making persons on board comfort is greatly reduced, with the development of maritime transport, the design of this issue specialized controllers have become particularly urgent. For these problems,this paper discusses the use of two of the original Fin for roll stability control to reduce vessel longitudinal motion, and the fin need to be reset in accordance with the ship vertical motion control.In order to analyze the movement of the ship's longitudinal sway and the ship's longitudinal motion stability control,we must first establish a mathematical model of longitudinal motion of the ship. In the article briefly discusses the problems encountered in mathematical modeling, as well as solutions. For hydrodynamic parameters and wave disturbance force and torque longitudinal, with the ship design and construction of auxiliary software Maxsurf 11 simulation calculations based on the principle of slices, hydrodynamic parameters can be quickly solved under certain sea conditions, speed and heading. For global hydrodynamic value with the encounter frequency change is obtained, adopting wave spectrum weighting method to process those data to get parameters required in the ship longitudinal motion modeling process. In this paper we mainly explore the ship longitudinal movement control base on fin stabilizer, hydrodynamic and a simple analysis before and after the combination of longitudinal motion of the boat fin stability control methods. After the ship hydrodynamic parameters obtained, the sample function wave disturbance force and torque, and the total additional force on the fins, complete the establishment of a mathematical model of longitudinal motion of the boat. In order to verify the ship motion mathematical model is reasonable,the established model for motion stability analysis.Ship's model is converted into a form of longitudinal motion equation of state space equations to solve ships sway such complex multi-input multi-output control problem by modern control methods in the paper. In control system fin use as disturbance compensation offset devices design LQR optimal state feedback controller, and using genetic algorithms to optimize weighted matrix of the objective function, so that longitudinal movement of the smallest boats. After the traditional vertical range of motion control, taking into account the effects of seasickness on board habitability, and try to comfort the passengers on board the ship as the control target motion control. Analysis of the incentives seasickness occurred,designing the controller based on mathematical models incidence of seasickness under irregular waves. The simulation results show that: In this paper, the design of the controller for the ship's heave, pitch, and the incidence of seasickness has some control effect, has a certain reference value.