The Optimization Of Control Hydrofoil And System Design Of Wave Piercing Catamaran

Wave Piercing Catamaran(WPC)is a new type of high-speed ships.Its most distinct ability is to transport passengers and freights in severe sea conditions at a high speed.However,its seakeeping performance is not desirable with the present of big waves while advancing at a high speed.How to improve the seakeeping performance and make passengers traveling more comfort has become the central issue in the design of a WPC.To reach the target,reducing pitch and heave of WPC is an effective way.The way to reduce the vertical motion of a catamaran will have great significance to marine transport business.The purpose of this paper is to optimize the design of the T-foil,the flaps and the motion controller of WPC to improve its vertical motion based on a mathematical model.The main works of this paper are as follows:Firstly,the current overseas and domestic research status of WPC and its attitude control system are studied and the research contents of this paper are brought out.After the coordinate system consist of a fixed coordinate and a moving coordinate is built,a mathematical model of a WPC is derived.A set of accurate two-degree of freedom equations of pitch and heave based on the structure of the WPC are established.Waves are considered as the only environmental disturbance.In order to have an accurate model,the strip theory is used to get the hydrodynamic parameters.After that,the WPC model is analyzed to ensure the static stability of it.Then,the design of the T-foil is optimized based on the accurate WPC model with CFD software by analyzing impacts of the main parameters of the T-foil and optimizing the parameters.The profile of the foil,the aspect ratio,the length of the wing and the wing shape are considered.After the parameters of the horizontal wing have been determined,the profile and the length of the strut as well as the location at where the T-foil will be installed have been taken into account.The suitability of the T-foil and the WPC is analyzed by calculating the forces and moments produced by the T-foil after the design of the T-foil.The parameters of the flaps as well as the forces and moments it can produce are also provided.Finally,the initial design of the entire system is completed with LabVIEW based on the state space model of the WPC.A model predictive controller(MPC)and LQG controller are designed due to the uncertainty of environmental disturbances.The advantages of the MPC controller are that it will not be affected severely by the internal mechanism as well as the accuracy of the model and the constraints of input and output of the model are able to be considered in the design of the controller.The MPC can do rolling optimization which gives control output and predictive model by comparing the reference trajectory value with the online corrected trajectory value then the next corrected trajectory value is given with the predictive model obtained in the former step.This closed-loop control structure ensures good results.By comparing the MSI(motion sickness incidence)of the passengers on the ship with and without T-foil,with LQG controller and MPC controller respectively,the necessity of employing control foils and motion controller is verified.The result also shows that the motion control system of WPC plays an important role in improving the vertical motions.