Design And Research Of Control System For Dynamic Positioning Systems For Ships

With the rapid development of world economy, the rapid growth of population on the earth, the supply of resources on the land has become increasingly tense, the world turned to regard the economic development of the sea, the development and exploration of marine resources have become more frequent. Thus Research on the mooring system of floating structures is a problem of great concern. Dynamic Positioning System (DPS) is a closed loop control system, its function is the role without the aid of mooring system, and can continue to detect the actual location of the ship and the target location error, and then the wind, waves and currents and other external interference power Account the impact of mission to restore the ship to the target location the size of the required thrust, and thrust the ship to the thrust of the distribution so that the thrust generated a corresponding thrust, so that the ship maintains in as far as possible the position which in the sea level requests.China has rich ocean resources and has a great future in ocean exploitation. Therefore, research on DP of mooring system has significant value because the ocean exploitation need DP system. Dynamic positioning system of ship include three main parts:measuring system, control system and thrust system, and the control system is the core. The tradition control theory has experienced the classical control theory and modern control theory,which are two important stages of a landmark, and now already developed to the intelligent control direction. And the fuzzy control is one kind of intelligent control. Fuzzy control theory develops very quickly when it was proposed by American scholar in 1970s because it based on fuzzy sets, fuzzy language, and fuzzy logic illation. And it pertains to nonlinear control, which imitates partly human control. It can get high control quality without precise mathematical model.In this paper, unlike other dynamic positioning ships fuzzy controller design,the controller design of Dynamic Positioning System for Ship is based on well-known Takagi-Sugeno (T-S) fuzzy logic system. T-S fuzzy model was proposed by Takagi and Sugeno in 1985, And its forwards part is expressed by fuzzy and backwards part is expressed by linearity equation, which make model have highprecise output and easy to design nonlinear control in linear strategy. In this paper, the process controller is designed using parallel distributed compensation (PDC) and linear matrix inequalities (LMI) theory. Because it is flexible to deal with global stability and design multi-variable system controller by means of Lyapunov function.When the fuzzy variable,the universe of discourse, and the fuzzy has be chosen. we use the LMI toolbox in MATLAB software to solve the fuzzy controller. Finally has carried on the simulation to the dynamic positioning system as well as has carried on the stability analyses. The result indicated that the system finally tends to be stable, the controller has the Lyapunov significance stability, the sound effect of the design fuzzy controller is very remarkable.