Fuzzy control for a liquid level system

This paper deals with the design of a fuzzy controller (FC) based on pole assignment method for the control of a liquid level system. The problem is to control level set point changes by adjusting the flowrate of liquid entering the tank through a feed pump [2], [5]. The behaviour of the closed loop fuzzy system controlled by the fuzzy controller is identical to the linear system whose state transition matrix is the desired one. The main objective of this paper is the use of the affine T-S fuzzy model to represent both the controlled system and the fuzzy controller taking into consideration the effect of the constant term. Most of the research works analyzed the T-S model assuming that the non-linear system is linearized with respect to the origin in each IF-THEN rule, which means that the consequent part of each rule is a linear function with zero constant term. This will in turn reduce the accuracy of approximating nonlinear systems [3].