Novel nonlinear control design for a two-dimensional airfoil under unsteady flow

In this paper, a particular class of trailing-edge flap-controlled two-dimensional aeroelastic systems with structural nonlinearities in plunging and pitching, and operating in an unsteady aerodynamic incompressible flowfield, is considered. By using the flap hinge torque of the trailing edge flap surface as the control input, a partial state feedback continuous adaptive controller is proposed in order to suppress the aeroelastic vibrations of the wing section model. It is shown that the control design with respect to an appropriately chosen output variable yields an asymptotic stability result for all three of the pitching, plunging, and flapping degrees of freedom. Numerical simulation results clearly demonstrate the effectiveness of the control strategy toward suppressing aeroelastic vibration at both pre- and post-flutter flight speed regimes.