Non-fragile nonlinear H∞ control with additive controller gain variations

This paper addresses the problem of non-fragile H_∞ controller design for nonlinear systems. The controller to be designed is assumed to have additive gain variations. Design method for state feedback is presented in term of positive definite solutions to Hamilton-Jacobi inequalities. The resulting design is such that the closed-loop system is robustly stable and has an L₂ gain bound with respect to the additive controller gain variations. A numerical example is given to illustrate the proposed methods.