Robust control design strategy with parameter-dominated uncertainty

Abstract

A robust controller design strategy is presented for systems, the parameters of which are affected dominantly by a few unknown physical quantities. The use of the functional dependence of the model parameters on these physical quantities results in an accurate description of the model uncertainty space. This potentially may lead to a better tradeoff between performance and robustness. The proposed procedure for modeling such uncertain systems relies on the linear-fractional-transformation algebra and reduction of the uncertainty block dimension. The resulting model can be used for control synthesis using any robust control design technique. In this work fi synthesis was adopted since it best fits the structured uncertainty model obtained. An example presents a controller design for an unmanned flight vehicle, the model parameters of which depend on the unknown mass of its payload. The aircraft equations are derived, and a p, controller is synthesized. The controller is compared to other control methods, and its advantages are demonstrated.