Research And Simulation Of Ship Roll Control In Turning Motion

Ship turning motion is a special state in ship sailing and turning performance is closely related to ship collision avoidance,turning,etc.It is a great threat to the safety of ship sailing considering certain angle of heel during turning process with roll angle caused by external disturbances.In this paper,ship's turning characteristics and rolling motion under still water and wave disturbance were investigated,after that particle swarm optimization PID controller and sliding mode anti-rolling fin controller based on disturbance observer in turnning motion are designed.In the end,these controllers are emulated and verified.The research mainly includes the following aspects:First,four degrees of freedom nonlinear model of ship motion is established based on the method of MMG,which concludes hydrodynamic force,force and moment acting on ships induced by rudders,fins,propellers and waves.Based on the established model,the ship motion simulation system is build through MATLAB.Secondly,ship turnning and rolling motion under still water,first order wave force and second order wave force are simulated based on the MATLAB simulation system.After that,the influence of initial speed,rudder angle,rudder angular velocity,wave height,initial wave angle on the ship's slewing trajectory and ship rolling motion were analyzed.After that,taking the Integral of Absolute Error(IAE)as the performance index,the three parameters of PID controller as the population positions,the particle swarm optimization PID roll controller was established based on the model of ship motion and the ship motion control system was simulated under the control of fin stabilizer.Simulation of the sea conditions of different speed,wave height and rudder angle is carried out to verify the control performance of particle swarm optimization PID control.Also,the disturbance observer is built to observe the disturbance so as to compensate it and the sliding mode inversion controller is designed to control the motion of fin stabilizer considering the ship nonlinear motion model.Simulation of ship rotation and roll motion under different sea velocities,sea wave heights and rudder angles is carried out to verify the anti-roll effect of ship fin stabilizer under the controller of solid mode control based on disturbance observer.At last,the particle swarm optimization PID controller and the sliding mode controller based on disturbance observer are compared,and the result is that sliding mode control achieves better results than that of the particle swarm optimization PID control in two aspects of rolling angle and fin angle saturation in the same condition.Although the particle swarm optimization PID controller can achieve good anti-rolling effect,but the sliding mode controller can effectively compensate wave disturbance and uncertainties in the model by establishing disturbance observer and the variable structure of controller,which improves the control efficiency of fin stabilizer and gain a better anti-rolling effect.