Research On The Vertical Motion Control To The High Speed Ship Based On H_∞

With the development of technology and the need for modernization of naval equipment,the speed of the ship has been increased, with new types coming out such as catamarans,hydrofoils, surface effect ships. However, with the raise of the speed, the hull MUNK torque also increase, at the rate of the square of the speed of ship, which causes longitudinal instability and the rate of seasickness rising. The current method is to install the T-foil and the flap on the bow and the stern of the high-speed ship respectively, and apply the appropriate control algorithm in the ship control system to control the attitude of the high-speed ship and reduce the rate of seasickness. This paper includes five major contents as follows:(1) The development of high-speed ship and the anti-rolling devices are introduced,mainly on the present research of the T-foil and flap at home and abroad, which are the actuator in this research.(2) In order to analyze the longitudinal motion of ship, the mathematical model of ship longitudinal motion is established. In addition, the hydrodynamic coefficients of the model and wave disturbance force are calculated, and the wave movement of the high-speed ship is simulated using the wave simulation method. Second, to guarantee the comfort of passengers on ship, the impact of incentives seasickness is analyzed, and the seasick rate model is built.The last part is the research of on anti-rolling effect of the static T-foil and flap at a fixed angle.(3) During the movement in the ocean, high-speed ships are not only influenced by the environmental uncertainties like the wave disturbances, but also those of the control system,so that it is necessary to take the system’s robustness into consideration. Another important element of the control system is the dynamic performance. However, in classical control methods of such uncertain parameters problems with the requirement of dynamic performance, the design process is complex and no solution to the method often appears. To solve these problems, this paper studies the longitudinal movement control based on QFT,establishes the model uncertainty, calculates performance indicators, and finally obtains controller using loop tuning.(4) Considering the uncertainty of the high-speed ship longitudinal motion model, the loop shaping method is adopted to design controller. The weight function is selected by the LMI theory, and the controller is obtained according to the value of output feedback gain. The order of the controller is also reduced to reduce the interference of high order.(5) The simulation model is built in MATLAB. The longitudinal motion are simulated in following situations: the QFT controller applied in the high-speed ship with a dual actuator,the QFT controller applied in the high-speed ship with a T-foil, the H∞ controller applied in the high-speed ship with a dual actuator, and the H∞ controller applied in the high-speed ship with a flap. The MSI are calculated from the data obtained from the simulation test, and with the comparison analysis, the feasibility of the controller based on QFT controller and H∞ loop shaping theory is studied.