Parametrization of nonlinear H∞ output feedback controllers-an algebraic approach via bounded real lemma

This paper exploits the bounded real lemma to find the H_∞ controllers of input-affine nonlinear systems. It is shown that the central solution and the parametrization of a class of nonlinear H_∞ controllers can be obtained at one stroke by repeatedly using bounded real lemma four times. The proposed approach involving only fundamental algebraic manipulations hopefully provides a simpler framework for finding the nonlinear H_∞ controllers from the view point of dissipative system