Research On Control Of Ship Fin Stabilizer/Tank Joint Anti-rolling System

Severe rolling has a serious impact on the seaworthiness and safety of the ship.The fin stabilizer/tank jointed anti-rolling system is a comprehensive anti-rolling device combining fin stabilizer and the controllable passive anti-rolling tank.This anti-rolling method can reduce the energy loss of the ship and achieve great anti-rolling effect at full speed by reasonably distributing the work share of the two anti-rolling devices.The nonlinear mathematical model of the fin/tank jointed anti-rolling system is investigated significantly in this thesis,the design of air valve switch controller for the controllable passive anti-rolling tank at low speed and the design of terminal sliding mode control for the fin/tank jointed anti-rolling system at medium and high speed.The main contents of this paper are as follows:(1)Based on the theory of statics and dynamics of ship motion and considering the nonlinear characteristics of ship rolling motion in high sea conditions,a nonlinear mathematical model of the jointed fin/tank anti-rolling system is established on basis of the nonlinear mathematical model of ship fin stabilizer and the nonlinear mathematical model of ship controllable passive anti-rolling tank.Referring to the parameters of a Ro-Ro ship,the rolling motion of the fin/tank jointed anti-rolling system model is simulated for different sea conditions,and correctness of the mathematical model is verified.(2)Based on the system of the ship fin stabilizer and the system of the ship controllable passive anti-rolling tank,the ship fin/tank jointed anti-rolling system is designed.At low speed,aiming at the problem of phase lag of water motion in the tank existing in the traditional control mode,and following the characteristics that the change of the roll angular velocity can be predicted according to the roll angular acceleration of the ship,the optimal phase PD control method is proposed to control the opening and closing of the air valve in the tank,so that the oscillation of water in the tank just lags behind the 900 phase angle of the rolling movement,and to maximize the anti-rolling ability of the tank at low speed.(3)At medium and high speed,aiming at the nonlinear factors in the fin/tank jointed anti-rolling model,the terminal sliding mode algorithm is introduced to solve the problem of poor robustness of conventional PID control.Aiming at the problem that terminal sliding mode control is prone to singularity and slow convergence speed,the fast nonsingular terminal sliding mode controller of the fin/tank jointed anti-rolling system is designed by combining the fast nonsingular characteristics with the advantages of terminal sliding mode.(4)The above controller design for medium and high speed is carried out under the background the parameters of the ship model are known,but in the actual complex sea condition,some parameters of the ship cannot be measured.By using the great approximation characteristics of the fuzzy adaptive control,and combined with fast nonsingular terminal sliding mode control algorithm,the fast nonsingular terminal fuzzy adaptive sliding mode controller of the fin/tank jointed anti-rolling system is designed,which makes the controller design independent of accurate ship model.The simulation research of fin/tank joint anti-rolling system is carried out under different speed and sea conditions in this thesis.The results show that the anti-rolling effect of controllable passive tank is better than that of passive tank at low speed,and the fast nonsingular terminal fuzzy adaptive sliding mode controller has the advantages of strong robustness,great adaptability and fast response at medium-high speed,which verifies the designed fin/tank joint anti-rolling system has great anti-rolling effect at full speed.