Integrated control laws are developed for stability augmentation and active flutter
suppression (AFS) of a flexible, flying-wing drone. The vehicle is a 12-pound unmanned, flying-
wing research aircraft with a 10 ft wingspan. AFS is flight critical since the subject vehicle is
designed to flutter within its flight envelope. The critical flutter condition involves aeroelastic
interactions between the rigid-body and elastic degrees of freedom; hence the control laws must
simultaneously address both rigid-body stability augmentation and flutter suppression. The
control-synthesis approach is motivated by the concept of Identically Located Force and
Acceleration (ILAF), successfully applied on some previous operational aircraft. Based on the
flutter characteristics and on conventional stability-augmentation concepts, two simple loop
closures are suggested. It is shown that this control architecture robustly stabilizes the body-
freedom-flutter condition, increases the damping of the second aeroelastic mode (which becomes
a second flutter mode at higher velocity), and provides reasonably conventional vehicle pitch-
attitude response. The critical factors limiting the performance of the feedback system are
identified to be the bandwidth of the surface actuators and the pitch effectiveness of the control
NASA NRA, "Lightweight Adaptive Aeroelastic Wing for Enhanced Performance Across the Flight Envelope," NRA NNX14AL36A, Mr. John Bosworth Technical Monitor.
Stability Augmentation and Active Flutter Suppression of a Flexible Flying-Wing Drone.
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