Relaxed design conditions for Takagi-Sugeno unknown input observers

New design conditions for the Takagi-Sugeno fuzzy model based unknown input observer, is presented in the paper. By the proposed methods, the design problem is parameterized in terms of linear matrix inequalities in relaxed and enhanced structures. Related to the state decoupling and reconstruction in the given class nonlinear systems, the design steps are revealed in the example for attenuation of an unknown input to the state estimation error.