TYPE-2 FUZZY LOGIC CONTROL r OF NON LINEAR SYSTEM

Abstract

Interval type-2 fuzzy logic controllers (1T2-FLCs) are recently attracting a lot of research attention. Type-2 fuzzy sets help US to model and minimize the effects of uncertainties in the rule-base of fuzzy logic systems. A type-2 fuzzy set is a fuzzy set in which there is uncertainty in the membership function also. We can say that typ-2 fuzzy logic is generalization of conventional fuzzy logic (type-I), that is, the uncertainty is not only limited to the linguistic variables but also present in the definition of the membership functions. In this work, an interval type-2 fuzzy logic controller (IT2-FLC) has been applied to a non-linear plant of CSTR (Continuous Stirred Tank Reactor). To describe the behaviour of CSTR, mass and component balance equations have been developed and a non-linear CSTR plant has been modelled with the help of those equations. Through MATLAB/Simulink environment, an IT2-1-LC has been designed and applied to the CSTR plant. The objective of the controller is to maintain the product concentration by adjusting one of the flow rates. The robustness analysis has also been performed on the 1T2-FLC designed for the non linear CSTR plant by varying different parameters of the plant and by changing the foot print of uncertainty (FOU) of the IT2-FLC. The analysis have shown that IT2-FLC is generally more robust than their type-i counter parts, as they are better able to cope with disturbances and uncertainties and eliminate oscillations. This is due to an additional degree of freedom provided by the foot of uncertainty