A Study On Fuzzy-PI Control Of Servo System Of Fin Stabilizer Based On PLC

Fin Stabilizer has great effects on increasing ship's qualities of seakeeping,of seaworthiness, of speed and of stabilization, as the same time it also improves the working conditions of equipments and of people aboard. Traking system of Fin Stabilizer accepts controlling signal, sent by main controller, which drive Fins move following with it. The tracking system is usually composed of "electrolic hydraulic servo system" in which there are many nonlinear factors and variable parameters. These nonlinear factors affect the dynamic and static characteristics of the tracking system,on the other hand weaken the advantages of super controlling algorithm of main controller. so, to invesigate a intelligent controlling algorithm to improve the adaptation of the servo system and improve effect of stabilization has pratical significance.The thesis inquire into the mathematical mode of servo system, firstly, in accordance with the principle of compose of servo system and principle of hydraulic pressure control, then choose the parameters of tracking system of a ship as parameters of mathematical mode. On the basis of characteristics of parts composing system, a conventional PI controller is disgned. Through simulating the dynamic response of PI controlling system designed without disturbance and with disturbance, a conclusion is drawed that the response of system become bad only with obstruction considered to affect system without considering other nonlinear factors such as friction, deadband and lag. If these nonlinear factors are considered, it will be difficult to keep tracking precision of system.Secondly, to deal with the nonlinear factors, author designes convention Fuzzy controller based on Fuzzy control theory, because of it's advantage on controlling objects that possess variable parameters and nonlinear factors. To remedy defect of convention Fuzzy controller in static precision control, a Fuzzy controller and a PI controller convinined is designed. When there appear bigger error, Fuzzy controller take control of system otherwise PI do it. This controller possesses advantages of Fuzzy and PI controller as the same time,it can improve abilities of system and stabilize ship better.The results of simulink show that Fuzzy-PI controller can track given signal better even when disturbance and nonlinear factors are added to system.At last a PI control algorithm programme based on PLC is designed.