We have proposed an infinite-dimensional observer for a class of Boundary Control Systems that allows to estimate the infinite-dimensional state variables and the damping coefficient associated tu the boundary damping. We have provided sufficient conditions to guarantee asymptotic convergence. In addition, we have proposed an adaptive output feedback control law in which the gain is adapted in function of the estimated damping coefficient. In this way, the closed-loop damping can be assigned even for the cases in which the damping is unknown or it changes in real time.

We have proposed a reduced-order dynamical observer for the flutter detection problem. From frequency domain data, we are able to build different aeroelastic model of the plane for different flight conditions. The damping associated to the flutter mode decreases much faster as the flight condition approached the flutter one (see Max. Singular Value Figure at frequency 24 rad/s approx). The mode can be isolated using inputs and outputs blending. Using these linear combinations of inputs and outputs one can highlight the flutter mode. Finally, for the flutter mode, we estimates the current damping using a dynamical observer. The damping parameter is well estimated for different flight conditions. This technique can allows to have an additional information concerning decay of damping in real time.