In this paper, an active flutter control scheme is investigated for a 2dof airfoil with nonlinear torsional stiffness. We use a simple graphical method to characterize all possible system equilibria. With the help of this method we study how an active flutter suppression system can lead to ”parasitic” steady states, which are different from the nominal zero-pitch, zero-plunge trim conditions. It appears that these equilibria can be induced by the presence of non-smooth saturation function, which describes amplitude constraints imposed on the system actuators. With control system built using only knowledge of ”nominal” system dynamics, the closed-loop system becomes structurally unstable in the sense that a small change in its parameters or the addition of infinitesimal unmodeled dynamics can lead to the ”parasitic” steady states appearance or disappearance.

A problem of reconstruction of the signals of sensors of the power flux monitoring (PFM) has been considered as an inverse problem which may be solved by use of the algorithms of assembling inverse filters derived on a basis of the asymptotically best and the best uniform approximations of the frequency characteristic. Such an approach to deriving the resulting filters whose frequency characteristics meet a specified condition for any a priori given error enables one to increase the PMF signal accuracy, and, hence the accuracy of the power flux calculations over the nuclear power reactor core volume.