Research On Control Method Of Active Anti Roll Tank Reduce Parametric Rolling

When the ships of smaller damping in longitudinal waves or close to the longitudinal wave sea encounter a certain frequency wave,accompanied by significant pitch and heave motion which produce a large roll angle in a short time, it is called parametric rolling.Parametric rolling is a form of nonlinear motion of the ships,which affects the operating efficiency and is a serious threat to the ship and cargo. The research on parametric rolling,begins in 1930s, has become a hot spot in recent years, especially the study about the parametric rolling in the real sea.Active anti roll tank is different from the passive anti roll tank. A water pump or other active force method is installed on even channel of the passive anti roll tank. The sensors are used to obtain the swing signals in order to control the valve, so that the water in the cabin moves direct to reduce the rolling, so the required stability moment is produced. Active anti roll tank can be used to suppress the parametric polling of ships with the advantages of simple structure, easy to control, and excellent reducing rolling effect. Two kinds of active anti roll tank controller are designed in this paper, and the simulation and comparison about the effects on parametric rolling of ships between passive and active anti roll tank are operated.Firstly, the research results of rolling tank and ship parametric rolling at home and abroad are summarized, the work principle on the reduction of active anti rolling tank and the roll cause are analyzed. The study models are established, including the waves mathematical model, parametric rolling motion model, nonlinear mathematical model of the ship. The Pitch and heave motion coupling effect to the rolling parameters is considered during the modeling. The solve method about system parameters is provided. The model is simplified aiming at the actual simulate and control design.Secondly, the stability of the ship in calm water, peaks and valleys are analyzed, and the corresponding effect on parametric rolling is studied. In regular waves, the effect about parametric rolling under different conditions is simulated. The conditions include speeds,wave height, roll damping and the ratio between rolling natural frequency and encounter frequency. In irregular waves, the simulation about the parametric rolling is studied.Finally, the inhibition effect of passive anti rolling tank to parametric rolling is simulated and analyzed. Based on passive anti rolling tank, the two kinds of active anti roll tank controllers are designed which roots on the nonlinear PID control theory and Lyapunov stability theory respectively. Using signal constraints in MATLAB module (Signal Constraint block), the parameters of PID controller for nonlinear systems are optimized, and the effectiveness of the control method is proved. In addition, the mathematical proof and simulation confirmation about the designed controller based on Lyapunov theory are conducted.