DISTURBANCE ATTENUATION AND H-INFINITY-CONTROL VIA MEASUREMENT FEEDBACK IN NONLINEAR-SYSTEMS

This paper presents a solution to the problem of disturbance attenuation via measurement feedback with internal stability for an affine nonlinear system. It is also shown that the concept of disturbance attenuation, in the sense of truncated L2 norms can be given-even in the nonlinear setup-an interpretation in terms of the response to periodic inputs in the sense of rms amplitude. Finally, in the case of state feedback, a family of controllers is also provided. The proofs of all these results are surprisingly simple and indeed provide deeper insight even in the analysis of the corresponding linear control problem.