Active control of an aeroelastic structure

Abstract

Linear and nonlinear aeroelastic response is modeled with an unique test apparatus that allows for prescribed plunge and pitch motion of a wing. The addition of a control surface, combined with a personal-computer based active control system, extends the stable flight region. Linear, steady aerodynamic theory provides a base for full-state feedback control. Incorporation of unsteady aerodynamic theory, modeled with an approximation to Theodorsen's classical unsteady theory, makes the model more realistic and complex. A Kalman estimator, coupled with a full-state feedback control law, is developed to stabilize the system above the open loop flutter velocity. Coulomb damping and pitch hardening are included to examine nonlinear control behavior. The nonlinear model is tested using the control laws developed with linear theory. Each theoretical model is simulated using Matlab[] and the experimental model of the active control system. An excellent correlation between theory and experiment is achieved for the models. Using a Kalman estimator and full-state feedback, the linear and nonlinear systems are stabilized at velocities which are 100% above the open loop flutter velocity.