Flutter control of aeroelasticity with freeplay nonlinearity

The question of active futter control of prototypical aeroelastic wing section in subsonic uncom-pressible flow was investigated. The aeroelastic dynamic model with freeplay nonlinearity in pitch was built using Theodorsen quasi-steady aerodynamic force and moment. Then the control law for flutter suppression was derived via state-dependent Riccati equation. For the synthesis of the controller, only pitch angle and control-surface deflection were measured directly. An observer was constructed to estimate the unavailable state variables of the system. The closed-loop system including the observer and nonlinear controler is asymptotically stable. The simulation results are presented, which show that the observer can give precise estimations for the plunge displacement and the velocities in pitch and plunge, and that the controller is effective for flutter suppression of two-dimensional airfoil with freeplay nonlinearity in pitch.