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Cooperative control theory and integrated flight and propulsion controlThe major contribution of this research was the exposition of the fact that airframe and engine interactions could be present, and their effects could include loss of stability and performance of the control systems. Also, the significance of two directional, as opposed to one-directional, coupling was identified and explained. A multivariable stability and performance analysis methodology was developed, and applied to several candidate aircraft configurations. In these example evaluations, the significance of these interactions was underscored. Also exposed was the fact that with interactions present along with some integrated control approaches, the engine command/limiting logic (which represents an important nonlinear component of the engine control system) can impact closed-loop airframe/engine system stability. Finally, a brief investigation of control-law synthesis techniques appropriate for the class of systems was pursued, and it was determined that multivariable techniques, including model-following formulations of LQG and/or H infinity methods, showed promise. However, for practical reasons, decentralized control architectures are preferred, which is an architecture incompatible with these synthesis methods. The major contributions of the second phase of the grant was the development of conditions under which no decentralized controller could achieve closed loop system requirements on stability and/or performance. Sought were conditions that depended only on properties of the plant and the requirement, and independent of any particular control law or synthesis approach. Therefore, they could be applied a priori, before synthesis of a candidate control law. Under this grant, such conditions were found regarding stability, and encouraging initial results were obtained regarding performance.
Document ID
19960003007
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Schmidt, David K. (Maryland Univ. College Park, MD, United States)
Schierman, John D. (Maryland Univ. College Park, MD, United States)
Date Acquired
September 6, 2013
Publication Date
September 25, 1995
Subject Category
Aerodynamics
Report/Patent Number
NAS 1.26:199418
NASA-CR-199418
Accession Number
96N13016
Funding Number(s)
CONTRACT_GRANT: NAG3-1575
CONTRACT_GRANT: NAG3-998
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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