Research On Heading And Track Control Of Large Ships In Different Ocean Condition

With the rapid development of world trade, port transportations are also increased very quickly, the number, size and tonnage of ships are changed with it. There are a lot of ships in harbour and near area, it makes the ship navigation's density increased and harbour's environment makes more dangerous and congested. Ships waste lots of time on entering and departing the harbour. So it is important to improve the maneuverability of ships for reduce the accidents. The autopilot that used for ship controls is essentially important equipment in shipping maneuvering. In our country, ships mount the PID autopilot broadly, which has course control function. There are lots of disadvantages in PID autopilot, just because complexity of shipping and limitation of PID controller. Considering the above situation the heading controller and the track controller based on Genetic Algorithm were brought forward.This thesis established the three unrestricted motion mathematical model of large ships based on the MMG separation formula, which discussed and analyzed the hydrodynamic forces and moments of the model, propeller thrust and propeller torque, the hydrodynamic forces and moments acted on the rudder and interferential forces and moments produced by wind, wave and current. The movement characteristics of large ships and the affect of winds, waves and currents were considered adequately in this model.Then applied the standard Runge-Kutta method to calculate the equation of maneuvering mathematical model by using Visual C++ programming language and MATLAB 7.0.Based on this work, the simulation of turning movement in the still water and the disturb of wind, wave and currents had been made. Next, the heading stability of large ships was discussed, and the instance was shown at last.Considering the effect on large ships of wind, wave and current in different ocean condition, designed the heading controller and the track controller by combining the Genetic Algorithm and control theory of PID, and accomplished the heading control simulation and the track control simulation by using this method.The analysis of simulation results showed that, the established motion mathematical model of large ships of three degrees of freedom was correct and practical, the designed heading controller and the track controller had a good performance in different ocean condition.