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Accession Number N20120014563
Title Analysis of Control Strategies for Aircraft Flight Upset Recovery.
Publication Date Aug 2012
Media Count 31p
Personal Author D. E. Cox D. G. Muri L. G. Crespo S. P. Kenny
Abstract This paper proposes a framework for studying the ability of a control strategy, consisting of a control law and a command law, to recover an aircraft from ight conditions that may extend beyond the normal ight envelope. This study was carried out (i) by evaluating time responses of particular ight upsets, (ii) by evaluating local stability over an equilibrium manifold that included stall, and (iii) by bounding the set in the state space from where the vehicle can be safely own to wings-level ight. These states comprise what will be called the safely recoverable ight envelope (SRFE), which is a set containing the aircraft states from where a control strategy can safely stabilize the aircraft. By safe recovery it is implied that the transient response stays between prescribed limits before converging to a steady horizontal ight. The calculation of the SRFE bounds yields the worst-case initial state corresponding to each control strategy. This information is used to compare alternative recovery strategies, determine their strengths and limitations, and identify the most e ective strategy. In regard to the control law, the authors developed feedback feedforward laws based on the gain scheduling of multivariable controllers. In regard to the command law, which is the mechanism governing the exogenous signals driving the feed-forward component of the controller, we developed laws with a feedback structure that combines local stability and transient response considera- tions. The upset recovery of the Generic Transport Model, a sub-scale twin-engine jet vehicle developed by NASA Langley Research Center, is used as a case study.
Keywords Aerodynamic stalling
Aircraft accidents
Aircraft maneuvers
Computerized simulation
Control systems design
Control theory
Deflection
Feedback control
Feedforward control
Flight envelopes
Mathematical models
Nonlinearity
Stability
Unsteady aerodynamics


 
Source Agency National Aeronautics and Space Administration
NTIS Subject Category 51C - Aircraft
Corporate Author National Aeronautics and Space Administration, Hampton, VA. Langley Research Center.
Document Type Conference proceedings
Title Note N/A
NTIS Issue Number 1308
Contract Number N/A

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