Variable Universe Fuzzy PID Control for Multi-level Gas Tank Pressure

This paper investigates pressure regulation for multi-level gas tank by variable universe fuzzy PID control. Pressure vessel is one of important equipments in process industry. Conventional PID controllers in gas tanks must set initial parameters in advance according to engineers´ knowledge, which will be unchanged during regulation. To remove these restrictions, variable universe fuzzy logic is applied to PID controller for parameters self-turning in this paper. By introducing the contraction and expansion factor of variable universe, both fuzzy universes and parameters of PID controller are on-line tuned, which improve the performance of controller. Finally, numerical simulation results showed the effectiveness of the proposed method.