Control synthesis for a class of uncertain nonlinear systems

The paper investigates the synthesis of nonlinear control systems with performance and stability robustness in the presence of parametric uncertainty. The proposed technique searches for a positive definite function that satisfies simultaneously design criteria stemming from the above requirements and recasts the general problem in the form of two nonlinear matrix inequalities (NLMI). Using nonconventional models, such as fuzzy approximates or global linearizations, the method provides constant-matrix or piecewise quadratic solutions