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Browsing by Subject "Control Law Synthesis"

Now showing 1 - 4 of 4
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    Application of MIDAAS to BFF Models
    (2014-11-23) Danowsky, Brian
    Modal Isolation and Damping for Adaptive Aeroservoelastic Suppression (MIDAAS) was applied to the BFF model at various flight conditions. All available control surfaces were used with nine sensors. MIDAAS synthesis produces a gain matrix feeding back all outputs to all inputs. Using these inputs and outputs, the resulting gain matrix is 9 by 8. Solutions were obtained for 3 different flight conditions (42, 44, and 50 knots). For each flight condition, a solution was obtained for two models, 1) bare airframe dynamics and 2) full system dynamics including bare airframe, actuator and sensor dynamics.
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    Flight-Dynamics, Flutter, and Active-Flutter-Suppression Analyses of a Flexible Flying-Wing Research Drone
    (As presented at the NASA Armstrong Flight Research Center Edwards AFB, CA, 2015-06-15) Schmidt, David
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    Flight-Dynamics, Flutter, and Active-Flutter-Suppression Analysis of a Flexible Flying-Wing Research Drone
    (Aerospace Flutter and Dynamics Council (AFDC) Meeting, Spring 2015, 2015-04-16) Schmidt, David
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    Stability Augmentation and Active Flutter Suppression of a Flexible Flying-Wing Drone
    (2015-05-19) Schmidt, David
    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 surfaces.