Sensitivity of Robust Flutter Boundary to Model Uncertainties in Aeroservoelastic Systems

The dynamics of a flexible air vehicle are typically described using an aeroservoelastic model which accounts for interaction between aerodynamics, structural dynamics, rigid body dynamics and control laws. These subsystems are individually modeled using a combination of theory and experimental data from various ground tests. For instance, the structural dynamics model can be obtained using a finite element method which is then updated using data from ground vibration tests. Similarly, an aerodynamic model can be obtained from linear panel methods or computational fluid dynamics and updated using data from wind tunnel tests. In all cases, the models obtained for the subsystems have a degree of uncertainty owing to inherent assumptions in the theory and errors in experimental data. By suitably modeling these uncertainties, a robust stability analysis may be carried out to obtain a robust flutter boundary. In this paper, we examine the affects of bounds on various uncertainties on the resulting robust flutter boundary. This analysis helps us deduce the subsystems most important for a good flutter prediction.