| Modern industries have proposed higher and higher quality requirements on steel plates. Plate thickness is very important factors reflecting plate quality. Therefore, higher requirements have been proposed on the executing structure and controlling system of rolling mills. Automatic gauge control (AGC) system is the key technique of modern rolling mills. Classical control theories are achieved on accurate mathematic models. Because of the complexity of steel rolling process, it is difficult to build an exact mathematic model for an AGC system. Intelligence control techniques are effect methods to solve this problem.In this thesis, on the base of analyzing steel rolling process, fuzzy PID control technique is applied on an AGC system. An automatic plate thickness control system based on fuzzy PID is proposed and achieved. Main job is as flow.(1) Main factors that influence the output thickness of rolling mills are theoretically analyzed. Reasons of impacting plate thickness and basic controlling methods of plate thickness are discussed respectively.(2) On the bases of theoretical model of hydraulic servo system and analyze of running mechanism of an AGC system, a dynamic mathematical model for hydraulic pressure AGC system is established.(3) Several existing control methods and their advantages and disadvantages are introduced and discussed, especially for fuzzy control.(4) A hydraulic pressure AGC system controlled by fuzzy PID is achieved.Base on the problem of thickness control, this text brings forword the new conjoint method of fuzzy control and PID controller. It constitutes intelligent complex controller, substitutes to tradition PID controller. And we carry through the small-scale experiment. The effect is better than tradition control. |
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