No abstract

No abstract

British Library Cataloguing in Publication Data Lind. Rick Robust aeroservoelastic stability analysis: flight test applications. -(Advances in industrial control) l.Flight control2.Aeroelasticity -Stability I.Title II.Brenner. Marty 629.1'326 ISBN-13:978-1-4471-1215-0 Library of Congress Cataloging-in-Publication Data Lind. Rick, 1968-Robust aeroservoelastic stability analysis: flight test applications / Rick Lind and Marty Brenner. p. em. --(Advances in industrial control) Includes bibliographical references (p. ).

A micro air vehicle is a flight system being designed for operation within urban environments. Such vehicles are small and highly agile but often have limited control authority. This paper investigates the use of morphing as an effector to provide control authority. Simple mechanisms for morphing are designed to twist the wings of a 24 in vehicle and to curl the wings of a 12 in vehicle. Flight tests show the morphing is an excellent strategy to command roll maneuvers. The resulting vehicles are relatively easy to fly and consequently are suitable for autopilot design and mission deployment.

No abstract

Biologically inspired concepts are rapidly expanding the range of aircraft technology. Consideration is given to merging two biologically-inspired concepts, morphing and micro air vehicles, and the resulting flight characteristics are investigated. Specifically, wing shaping is used to morph the membrane wings of a micro air vehicle. The micro air vehicle has poor lateral control because hinges, and consequently ailerons, are difficult to install on a membrane wing. Instead, a set of torque rods, aligned along the wings, are used to twist the membrane and shape the wing. The resulting morphing is shown to provide significant control authority for lateral dynamics. A set of flight tests are undertaken to determine the flight characteristics by commanding pulses and doublets to the control actuation. The vehicle demonstrates excellent roll performance in response to wing shaping. Futhermore, the vehicle demonstrates several types of spin behavior related to combinations of elevator deflection and the wing shaping.

A class of micro air vehicles uses a flexible membrane wing for weight savings and passive shape adaptation. Such a wing is not amenable to conventional aileron mechanisms for roll control, due to a lack of internal wing structure. Therefore, morphing (in the form of asymmetric twisting) is implemented through the use of a torque-actuated wing structure with thousands of discrete design permutations. A static aeroelastic model of the micro air vehicle is developed and validated to optimize the performance of the torque-actuated wing structure. Objective functions include the steady-state roll rate and the lift-to-drag ratio incurred during such a maneuver. An optimized design is obtained through the use of a genetic algorithm presenting significant improvements in both performance metrics compared with the baseline design.= objective function L=D = lift-to-drag ratio p = roll rate U1 = freestream velocity W = transverse wing displacement x LE = leading-edge coordinate y LE = leading-edge coordinate z LE = leading-edge coordinate C P = differential pressure coefficient = objective function weighting parameter

Hypersonic flight conditions produce temperature variations that can alter both the structural dynamics and flight dynamics. These aerothermoelastic effects are modeled by a nonlinear, temperature-dependent, parameter-varying state-space representation. The model includes an uncertain parameter-varying state matrix, an uncertain parameter-varying nonsquare (column-deficient) input matrix, and a nonlinear additive bounded disturbance. A Lyapunov-based continuous robust controller is developed that yields exponential tracking of a reference model, despite the presence of bounded nonvanishing disturbances. Simulation results for a hypersonic aircraft are provided to demonstrate the robustness and efficacy of the proposed controller.