Design of fuzzy I-PD controller for level control of spherical tank system

The Control of non-linear process is a highly demanding task in many process industries and the spherical tank system is one among them. In this paper, the control of liquid level of single spherical tank system is considered. The system model is identified by using black box method and the First Order Plus Time Delay (FOPTD) models are obtained for different regions of the system. Initially, the PID controller based on Ziegler Nichols (ZN) tuning method is designed and then the performance of the system is compared with I-PD, Fuzzy PID and Fuzzy I-PD controllers. From the simulation results, it is inferred that the Fuzzy I-PD controller provides better level control action when compared with other controllers.