Design of a novel fuzzy adaptive PI controller for monitor hydraulic AGC system of cold rolling mill

In every rolling process, the automatic gauge control (AGC) system is the core of the control unit. Traditionally, PI controllers are used in these systems to achieve the desired strip thickness. The major problem of this controller is its high sensitivity to parameters variations and external disturbances. This is due to the complex structure and highly nonlinear dynamic model of these systems. In this paper a novel fuzzy adaptive PI controller is proposed, as a remedy to this problem. This controller is designed on the basis of professional knowledge to tune PI parameters in proportion to thickness error, thickness error change rate, and desired exit thickness. A dynamic mathematical model of the system is derived whose accuracy is confirmed through practical tests and then the performance of the proposed controller for a real cold mill is evaluated by model-based simulation. The influences of parameters perturbation is taken into account. Simulation results show that the response speed and robustness of the fuzzy adaptive PI controller are much better than the traditional PI scheme.