Research On The Vertical Motions’ Control System Of A Fast Multi-body Ship Based On Longitude Damping Devices

In recent years,with the development of the technology of ship-manufacturing technology in the world,some new ships also came into being.In a lot kind of new ships,compared to single-hull ships,multi-body ships have superior buoyancy and stability,wave-resistance,maneuverability and invisibility,which can be loaded in large quantities and have strong anti-strike capability,so it has been widely used in civil and military fields.However,when the multi-body ship is in rapid sailing,the ship has experienced a large longitudinal movement,which reduces the comfort and safety of the ship,and causes serious damage to the ship equipment and the reduction of the efficiency of the hull engine.Many researchers in the world have done a great deal of researches on reducing the longitudinal movement of ships at high speed,and installing actuators to the hull has the highest frequency of use.In this paper,the T-foil and flaps are used as the longitude damping devices of the multi-body ship,and the longitudinal movement of the multi-body ship during high speed navigation is analyzed.Firstly,the mathematical model of pitch and heave motion of multi-body ship is introduced and analyzed.The hydrodynamic coefficient of high-speed multi-body ship is calculated by ANSYS,and the model of multi-body ship is identified.The longitude damping principle of the T-foil and flaps is analyzed.Mathematical models of the waves,the multi-body ship,the T-foil and flaps are established respectively.Then use MATLAB SIMULINK to establish multi-body ship longitudinal motion simulation system.The open-loop analysis of high-speed multi-body ship was carried out,and the influence of two aspects on the longitudinal motion of the ship from the sea wave and the longitude damping devices are studied.The closed loop control system of high-speed multi-body ship is established by using PD algorithm and fuzzy control as the control law of the system.The heave motion and pitch motion of the high speed multi-body ship is simulated,and the control effect of the two control methods is compared.The simulation of heave reduction and pitch reduction control system is carried out,and the coupling of the system is obtained according to the simulation curve.In order to limit heave and pitch motion simultaneously,the system needs to be decoupled so that only one output is controlled for each input.Finally,the structure layout of the T-foil and flaps is simulated under different sea conditions.In this paper,a series of basic laws of hull movement obtained,and laying the foundation for further research on longitude damping of multi-body ships.Through the design and improvement of the system,the longitudinal motion of the ship is greatly restricted,and the longitudinal motion performance of the high speed multi-body ship is enhanced.