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  • Cybernetics  (2)
  • Aircraft Design, Testing and Performance; Aircraft Propulsion and Power  (1)
  • General  (1)
  • 1
    Publication Date: 2019-07-10
    Description: This report represents an attempt to see if some of the techniques biological systems use to maximize their efficiency can be applied to the problems NASA faces in aeronautics and space exploration. It includes an internal survey of resources available at NASA Langley Research Center for biomimetics research efforts, an external survey of state of the art in biomimetics covering the Materials, Structures, Aerodynamics, Guidance and Controls areas. The Biomimetics Planning team also included ideas for potential research areas, as well as recommendations on how to implement this new program. This six-month survey was conducted in the second half of 1999.
    Keywords: General
    Type: NASA/TM-2002-211445 , L-18153 , NAS 1.15:211445
    Format: application/pdf
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  • 2
    Publication Date: 2019-07-13
    Description: This paper presents an iterative Linear Quadratic Gaussian (LQG) controller design approach for a linear stochastic system with an uncertain open-loop model and unknown noise statistics. This approach consists of closed-loop identification and controller redesign cycles. In each cycle, the closed-loop identification method is used to identify an open-loop model and a steady-state Kalman filter gain from closed-loop input/output test data obtained by using a feedback LQG controller designed from the previous cycle. Then the identified open-loop model is used to redesign the state feedback. The state feedback and the identified Kalman filter gain are used to form an updated LQC controller for the next cycle. This iterative process continues until the updated controller converges. The proposed controller design is demonstrated by numerical simulations and experiments on a highly unstable large-gap magnetic suspension system.
    Keywords: Cybernetics
    Type: NASA-CR-203238 , NAS 1.26:203238 , Journal of Dynamic Systems, Measurement and Control; 118; 366-372
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  • 3
    Publication Date: 2019-07-13
    Description: An algorithm is presented for identifying a state-space model of linear stochastic systems operating under known feedback controller. In this algorithm, only the reference input and output of closed-loop data are required. No feedback signal needs to be recorded. The overall closed-loop system dynamics is first identified. Then a recursive formulation is derived to compute the open-loop plant dynamics from the identified closed-loop system dynamics and known feedback controller dynamics. The controller can be a dynamic or constant-gain full-state feedback controller. Numerical simulations and test data of a highly unstable large-gap magnetic suspension system are presented to demonstrate the feasibility of this indirect identification method.
    Keywords: Cybernetics
    Type: NASA-CR-203237 , NAS 1.26:203237 , Journal of Guidance, Control, and Dynamics; 19; 4; 836-841
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  • 4
    Publication Date: 2019-12-10
    Description: Distributed Electric Propulsion technology is expected to yield up to a fivefold increase in high-speed cruise efficiency for NASAs X-57 Maxwell flight demonstrator when compared to a combustion-powered general aviation baseline. A portion of this increased efficiency is due to beneficial aero-propulsive interaction inherent to the distributed propulsion architecture. The measure of the relative increase in efficiency between a conventional and distributed propulsion wing will be extracted from comparisons between flight test data from the electrically powered X-57 Mod II configuration with a conventional wing, and from the electrically powered X-57 Mod III/IV configuration with a distributed propulsion wing. Flight test maneuvers that accommodate errors in instrumentation and the flight test environment are developed to establish the power-off drag characteristics for all X-57 configurations. Analysis of these maneuvers with typical errors, including pilot-in-the-loop simulation data that incorporates simulated atmospheric turbulence effects, shows that the proposed power-off flight maneuvers can generate accurate power-off drag predictions for the X-57. These predictions show that the power-off differences in aerodynamic performance between the conventional and distributed propulsion configurations can be accurately measured from flight test data in the presence of typical data error sources.
    Keywords: Aircraft Design, Testing and Performance; Aircraft Propulsion and Power
    Type: NF1676L-31784 , AIAA Aviation Forum and Expo; Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
    Format: application/pdf
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