Analysis of Control Strategies for Aircraft Flight Upset Recovery

Luis Crespo, Sean Kenny, David Cox, Daniel Murri
2012 AIAA Guidance, Navigation, and Control Conference   unpublished
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 flight conditions that may extend beyond the normal flight envelope. This study was carried out (i) by evaluating time responses of particular flight 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 flown to
more » ... ely flown to wings-level flight. These states comprise what will be called the safely recoverable flight 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 flight. 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 effective 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 feedforward component of the controller, we developed laws with a feedback structure that combines local stability and transient response considerations. 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.
doi:10.2514/6.2012-5026 fatcat:qu6pwizbwfehxek7kifarvoa4i