DocumentCode :
2478548
Title :
Constraint enforcement for scramjet-powered hypersonic vehicles with significant aero-elastic-propulsion interactions
Author :
Soloway, Don ; Rodriguez, Armando A. ; Dickeson, Jeffrey J. ; Cifdaloz, Oguzhan ; Benavides, Jose ; Sridharan, Srikanth ; Kelkar, Atul ; Vogel, Jerald M.
Author_Institution :
Ames Res. Center, NASA, Moffett Field, CA, USA
fYear :
2009
fDate :
10-12 June 2009
Firstpage :
3154
Lastpage :
3159
Abstract :
In this paper, we examine the control of a scramjet-powered hypersonic vehicle with significant aero-elastic-propulsion interactions. Such vehicles are characterized by open loop unstable non-minimum phase dynamics, low frequency aero-elastic modes, significant coupling, and hard constraints (e.g. control surface deflection limits, thrust margin). Within this paper, attention is placed on maintaining acceptable closed loop performance (i.e. tracking of speed and flight path angle commands) while satisfying hard control surface deflection constraints as well as stoichiometrically normalized fuel-equivalency-ratio (FER) margin constraints. Control surface constraints are a consequence of maximum permissible aerodynamic loading. FER margin constraints are a consequence of thermal choking (i.e. unity combustor exit Mach number) and the fact that thrust loss may not be captured for FER greater than unity. Such limits are particularly important since the vehicle is open loop unstable and ldquosaturationrdquo can result in instability. To address these issues, one can design conservative (i.e. less aggressive or lower bandwidth) controllers that maintain operation below saturation levels for anticipated reference commands (and disturbances). Doing so, however, unnecessarily sacrifices performance - particularly when small reference commands are issued. Within this paper, the above issues are addressed using generalized predictive control (GPC). A 3DOF longitudinal model for a generic hypersonic vehicle, which includes aero-elastic-propulsion interactions, is used to illustrate the ideas.
Keywords :
aerospace propulsion; aircraft control; closed loop systems; open loop systems; predictive control; aeroelastic-propulsion interactions; closed loop performance; constraint enforcement; flight path angle commands; generalized predictive control; maximum permissible aerodynamic loading; normalized fuel-equivalency-ratio; open loop unstable nonminimum phase dynamics; scramjet-powered hypersonic vehicles; unity combustor exit Mach number; Aerodynamics; Aerospace control; Aerospace engineering; Elevators; Frequency; Marine vehicles; NASA; Open loop systems; Predictive control; Vehicle dynamics;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
American Control Conference, 2009. ACC '09.
Conference_Location :
St. Louis, MO
ISSN :
0743-1619
Print_ISBN :
978-1-4244-4523-3
Electronic_ISBN :
0743-1619
Type :
conf
DOI :
10.1109/ACC.2009.5160715
Filename :
5160715
Link To Document :
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