Research On Simulation And Control Strategy Of U-tube Anti-rolling Tank

Anti-rolling tank is widely used as a kind of full speed stabilizing unit because of its simple structure, low cost and high damping efficiency.Among those ,the passive anti-rolling tank gets pervasive application because it has no additional energy consumption and a large number of merchant vessels use passive anti-rolling tank at present. Active water tank is rarely applied to ship roll reduction because it needs to consume large amounts of energy and it has low cost performance.Controllable passive water tank is presented on the basis of the passive water tank.It has satisfactory stabilization effect under the different environment by using smaller control strategy to increase or decrease the flow of water in the tank. Engineering practice shows that controllable passive water tank can applied to improve the comfort and safety to various types of ships. At the same time it can also improve the efficiency of loading and unloading,reduce costs to achieve maximum efficiency.This paper firstly analyzes the moving laws of fluid in the anti-rolling tank and the force and moment on six degrees of freedom acting on the hull caused by fluid oscillation in the tank. By analysing and decucrion, we build the motion model of the ship on six degrees of freedom , rolling model of the ship (linear and nonlinear), fluid motion model in the tank and ship-water tank system model of the ship.Then we explore the influence to ship rolling motion by parameters of the tank including the natural frequency ,damping ,the location of the water tank to the ship .Next,we use Simulink module of MATLAB to conduct simulation analysis to the mathematical model of water tank, study the stabilizing efficiency by water tank(with/without), sea state, speed and encounter angle. Combined with the theory of optimal control method deduced,we study the control method of controllable passive anti-rolling tank valve . The comparison of optimal control method to conventional control method shows that the damping effect of anti-rolling tank is closely related to water tank valve control, that is to say, the key to improve the damping effect is to put forward more accurate and efficient control method. We use program compiled by MATLAB to conduct simulation and the result shows that figure out the best control method is an effective method to make the controllable passive anti-rolling tank have a wider damping range.