Eigenstructure assignment for a tailless aircraft
Item
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Title
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Eigenstructure assignment for a tailless aircraft
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Identifier
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d_2009_2013:47c86ea8076a:11343
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identifier
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11664
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Creator
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Nieto-Wire, Clara B.,
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Contributor
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Kenneth M. Sobel
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Date
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2012
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Language
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English
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Publisher
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City University of New York.
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Subject
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Electrical engineering | Aerospace engineering | Delta Operator Model | Eigenstructure Assignment | Fault Detection and Isolation | Reconfigurable Control | Robust Flight Control | Tailless Aircraft
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Abstract
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In the first part of our work we apply eigenstructure assignment to the design of a flight control system for a wind tunnel model of a tailless aircraft. The aircraft, known as the innovative control effectors (ICE) aircraft, has unconventional control surfaces plus pitch and yaw thrust vectoring. We show how to modify the desired eigenvalues to simultaneously achieve acceptable responses to pilot commands, stabilize the phugoid mode, satisfy MIL-F-8785C mode specifications and satisfy MIL-F-9490D specifications on phase and gain margins.;We use the unified delta operator model to obtain a flight control system for the ICE aircraft that is valid for both continuous time and sampled data operation. We prove a new result that extends disk gain and phase margins to the delta operator system. We consider symmetric lock in place failures of either the elevons or the all moving tips. We propose a novel eigenstructure assignment reconfiguration capable of maintaining stability, desired performance, and disk gain/phase margins of the ICE aircraft under symmetric lock in place failures in the lateral control effectors.;In the second part of our work we extend multiple and simultaneous fault detection and isolation (FDI) system design by a single diagnostic observer to the delta operator model. First, we reformulate the detection filter problem and detectability conditions for delta operator systems. Then, we present (1) the mathematical results that extend fixed directional residuals to delta operator systems, (2) the conditions for allowable failures, (3) a new projection matrix W that is independent of eigenvectors to diagonalize the failure/residual map, (4) a method for computing the observer gains for delta operator systems, and (5) a new result for the delta operator model fault free residual bound. Based upon these mathematical results, we propose a new eigenvector selection criterion for robust FDI to unstructured uncertainty and known initial condition mismatches. Then, we present a new method/algorithm for multiple and simultaneous FDI of actuator failures for delta operator systems which is capable of monitoring a variety of failures in the control actuators.;We consider the linearized longitudinal dynamics of a VTOL aircraft in the vertical plane subject to the combined and separate effects of an initial condition mismatch in the vertical velocity state and bias actuator failures of the pitch control and the longitudinal pitch control. We show that FDI system design by fixed directional residuals that use eigenstructure-based optimizations result in different sets of eigenvectors. Thus, residual responses can vary significantly. In contrast, our optimization and simulations results show that our algorithm for FDI yields well-conditioned residual generators with excellent and tightly consistent residual responses with detection time of 4 ms for 1ms sampled data operation.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Engineering
