Study Of Main/Flap Rudders Intelligent Coordinated Control For Ship Course-keeping

Main/flap rudders coordinated control can improve ship maneuverability. Nowadays, the main and flap rudders are connected by leaders or gears in engineering. It has certain angles ratio, and the effect of main/flap rudders is restricted. The thought that main and flap rudders are divided into two independent control systems is put forward in this paper, and the main/flap rudder intelligent coordinated control system for ship course-keeping is designed.Firstly, the hydrodynamic performance model of main/flap rudder is founded. The charts of main/flap-rudder-hydrodynamic coefficients are smoothed down. The regress equations are acquired by the characters of curves. The coefficients of regress equations are gotten by means of the least square algorithm. The remarkable test is carried out to make sure that the calculating models of main/flap-rudder-hydrodynamic coefficients can be used in engineering.Secondly, the model of the main/flap rudder control system for ship course-keeping is founded. Ship dynamic equations of yawing, rolling and swaying are founded based on momentum theory and momentum torque theory. The force and moment on the ship are studied, including the force of water, on the rudder, and the disturbance of wave, wind and current. The calculating model of these forces and moment are given. The model of system driven energy is studied primarily, and it establishes the base for the design of main/flap rudder intelligent coordinated control system for ship course-keeping.Then, the main/flap rudders intelligent coordinated control system for ship course-keeping is designed. For a restoring moment in the main/flap rudder, there are many kinds of main/flap-rudder angles. So this paper gives the rules of main/flap-rudder-angle intelligent optimizing assignment. The fuzzy controller of ship course-keeping is designed. It includes steps of defining the input and output variables of fuzzy controller, fuzzification of the input and output variables, design of fuzzy control rules, fuzzy inference and de-fuzzification.At last, the control system simulations in different sea conditions and encounter angles are carried out. The curves and statistic values of yawing angle, rudder angle and flap-rudder angle are given. Compared with common rudder and main/flap rudders with certain angle ratio in the style of PID control or fuzzy control, this system has higher course control precision, better robust performance and much less energy consumption.