Amélioration robuste de la stabilité par augmentation du nombre de degrés de liberté contrôlés

International audienceIn this article we demonstrate the necessity of increasing the number of controlled degrees of freedom when controlling an uncertain system. We show this on an infinite dimensional system representative of reaction-diffusion problems. However, our final goal is concerned with fluid flow control. In both cases, fluid flow control or reaction-diffusion problems, a common approach to control is based on a spatial discretization followed by some linear control design. Unfortunately, this approach is sensitive to uncertainties in- troduced during linearization of the nonlinear system. In this paper, we show that robust stability is dependent on the number of controlled degrees of freedom and performance of a closed loop system can be improved by considering this aspect