Effect of Control Constraints on Active Stabilization of Flutter Instability

The effect of amplitude and rate control constraints in active flutter suppression was analysed for a number of different linear and nonlinear control laws considering mathematical model of two degree-of freedom aeroelastic airfoil system with trailing and leading edge flaps. The LQR control law providing maximum region of attraction for the linearized system under amplitude control constraints was investigated taking into account a structural nonlinearity and actuator rate constraints. The region of attraction of a stabilized equilibrium was used as a metric to identify a set of linear control laws providing practically global stabilization of flutter instability with account of structural nonlinearities and rate control constraints. The eigenstructure assignment method was implemented for control law design considering trailing edge flap or a combination of leading and trailing edge flaps.