A fuzzy control scheme for nonlinear process

The aim of this paper is to design a fuzzy logic controller for the conical tank liquid level system. Control of liquid level in a conical tank is nonlinear due to the variation in the area of cross section of the tank system with its change in shape. The model of the process is identified using standard step response based system identification technique and it is approximated to be a first order plus dead time (FOPTD) model. The fuzzy controller is designed by gaining the error response of internal model control (IMC) based on Chien and Fruehauf´s settings. From the results it is observed that fuzzy controller shows much better integral absolute error (IAE) and integral squared error (ISE) performance criteria than the conventional controller.