H_infinity Observer-Based Control for Uncertain Fuzzy Systems with Application of the Quadruple-Tank Process

Abstract

This paper considers the problem of designing an H∞ observer-based controllers for continuous nonlinear systems presented by Takagi–Sugeno (T–S) model with the presence of parameter uncertainties and external disturbance. Some change of variables has been developed to linearize the bilinear terms. As a consequence, the bilinear problem conditions are converted into a set of Linear Matrix Inequalities (LMIs). Sufficient conditions f or design t he observer and controller gains are deduced in terms of LMIs conditions which can be practically solved in single step. The four-tank process application is used to show the effectiveness of the proposed method, revealing a better compromise between the simplicity and the conservatism of design method, outperforming in respect to previous approaches.