Positive observer design for continuous-time Takagi-Sugeno systems

This paper presents a positive observer design methodology for Takagi Sugeno systems with unmeasurable premise variables. For that, a positive Takagi-Sugeno observer is developed in order to estimate the system states and to guarantee the nonnegativity of the estimates at each time. Conditions are established in order to guarantee the convergence of the state error. These conditions are given as Linear Matrix Inequalities (LMIs) which makes possible to obtain the gains of the fuzzy observer. Finally, simulation results show the effectiveness of the proposed positive observer.