Research On Attitude Control Of Wave-piercing Catamaran With Stern Flap

In recent decades,the rapid development of modern science and technology has brought new changes to the traditional marine vehicles.As high-tech ships that have attracted much attention in the field of modern ship,Wave Piercing Catamarans are known for their high speeds and advanced technologies.The good seakeeping,stability and rapidity of them bring great convenience to ocean transportation,resource development and marine military competition.However,Wave Piercing Catamarans’ longitudinal motion stability is poor at a high speed and some severe sea conditions due to the their own structure(the hulls are thin and linear),which may easily cause adverse effects such as slamming,water on deck,and stall.At the same time,the high frequency of tremor and vertical acceleration caused by the waves can easily cause fatigue and discomfort to the passengers on board.Therefore,reducing the longitudinal movement of the WPC and improving the passenger’s comfort evaluation are of great significance to the development of the ship.The purpose of this paper is to design a controller to balance the wave interference with appropriate control measures and control hydrofoils(stern flap)installed on the stern,so as to improve the longitudinal motion performance of the ship.Firstly,the paper gives a brief overview of the historical background,research significance and research status of the wave piercing catamarans and integrated attitude control system.Accordingly,the research object selected in this paper is a wave piercing catamaran with stern flaps.Secondly,the motion equations of the wave piercing catamaran in the waves are established according to Newton’s kinematics theory in the case of only considering the wave interference,and then decoupled to obtain the heave-pitch model concerned by the research.Considering the limitations of the relevant conditions,the object can be simulated by the CFD software(Maxsurf)in order to solve the hydrodynamic parameters in the motion model quickly and easily.To analyze the simulation datas,the parameters used in the final determination are determined by finding the dominant frequency point.At the same time,the model of wave interference is obtained by linear superposition theory.Subsequently,the simulation study of stern flap through Fluent is carried out under the selected flow field conditions,and the corresponding relationship between the lift and the attack angle is obtained to determine the lift coefficient of the stern flap.Therefore,the lift/torque model of the stern flap is completed.Then,on the basis of the model of wave piercing catamaran without stern flap,we can finally obtain the space state model of longitudinal movement about the catamaran with stern flap installed.Next,the system simulation under the action of PID controller is completed according to the specific wave piercing catamaran in this paper.Finally,two different control measures(linear quadratic Gaussian algorithm and model prediction algorithm)are used to design the integrated attitude controller in order to overcome the shortcomings of traditional PID controllers.The simulation study was completed in Matlab/Simulink,and the simulation results were statistically analyzed to verify the good antirolling effect of the stern flap driven by the two controllers.Then,compare the difference of the anti-rolling effect under the two controllers,and analyze the cause of the difference.