Active flutter suppression of a two-dimensional airfoil using H_∞ synthesis

This paper presents how to use the ultrasonic motor as an actuator in the robust control of the flutter of a two-dimensional airfoil section with control surface. The study begins with the combined theoretical and experimental modeling for the aeroservoelastic system with damping uncertainty in plunge and pitch directions and the modeling error of ultrasonic motor taken into consideration. Then, it focuses on the design of a controller using H_∞ synthesis. The numerical simulations and wind tunnel tests show that the H_∞ controller is able to suppress the flutter effectively and the critical flutter speed of controlled system is increased by 23.4%.