On the robustness of linear systems with nonlinear uncertain parameters

The present paper studies the stability robustness problem of an uncertain state-space system. We propose a new uncertain state-space model which allows second-order uncertain parameters. The uncertainty in the model appears in the form of a combination of "additive perturbation" and "multiplicative perturbation". It is shown that the model has a strong practical background. A robustness criterion based on the model is derived. An example shows advantages of the proposed approach. (C) 1998 Elsevier Science Ltd. All rights reserved.