Multivariable control system synthesis based on the unknown-but-bounded disturbance model

Hard constraint bounding results are summarized along with additional new results. The authors derive bounds for the outputs and the states of systems disturbed either by uncertain inputs or modeling errors, using either boxes or ellipsoids as the constraint sets. The bounding results are summarized, based on either the concept of matrix measures or F.C. Schweppe´s (1973) ellipsoidal bounds. The theoretical results are applied to a simplified model of a physically meaningful system, namely, a steam-boiler model, with encouraging results. For the class of nonlinear systems represented by the boiler model, it is concluded that even if a box-bound-based control system provides more conservative results, as compared to alternate bounding approaches, it is more attractive and desirable because of certain practical implementation issues, such as the limitation on realizable actuator bandwidth