Flutter detection using reduced-order dynamic isolation observer

This article deals with the damping estimation of a single mode for multiple-input-multiple-output high-order linear time-invariant systems. The mode of interest is isolated by an optimal blending of the input and output vectors. Since the blended model appears similar to a single-input-single-output second order system, we propose a dynamic observer aiming at the damping estimation of such a reduced-order model. Applying the interconnection and damping assignment passivity-based observer technique for the design, the asymptotic convergence of the observer is shown using the LaSalle's invariance principle. Finally, the damping estimator is illustrated through numerical simulations of a generic flexible aircraft model obtained from frequency samples provided by AIRBUS.