Su, S. W.Brian, D. O.Anderson, B. D.O.Brinsmead, T. S.2026-01-012026-01-010743-1546ORCID:/0000-0002-1493-4774/work/174739474https://hdl.handle.net/1885/733799035The disturbance suppression problem for nonlinear systems is examined in this paper. We review the so-called nonstandard mixed sensitivity problem, which introduces an integrator to a selected weight, as well as the linear classical disturbance suppression problem and the linear H∞ disturbance suppression problem. We extend this H∞ problem to the nonlinear case, and present a method to reduce the order of the state feedback Hamilton-Jacobi PDE (Partial Differential Equation) for this nonlinear H∞ problem by extending the concept of comprehensive stability [8] [7]. Finally, we investigate the structure of the output feedback H∞ controller for disturbance suppression, and draw the conclusion that, as in the linear case, there must also be an integrator in the controller.en200010.1109/CDC.2000.9142810034439586