Automatic flight envelope recovery for large transport aircraft

[摘要] ENGLISH ABSTRACT: This thesis presents the design of an automatic flight envelope recovery system for large transportaircraft. The flight envelope of the aircraft is conceptualised to consist of the aerodynamicenvelope, the attitude envelope, the flight vector envelope, and the structural integrity envelope.The time scale separation between the aircraft's fast rigid body rotational dynamics andits slower point mass translational dynamics is exploited to separate the flight envelope recoveryinto an inner-loop recovery of the angular rates and aerodynamic envelope, and an outer-looprecovery of the attitude, flight path angle, and airspeed while remaining within the structuralintegrity envelope.Two approaches to flight envelope recovery are proposed. The first approach uses a passivemethod to recover the aerodynamic envelope using the natural stability of the aircraft andthen uses the conventional flight control laws, with their flight envelope protection functions,to recover the aircraft attitude and flight vector. The second approach uses an active methodto recover the aerodynamic envelope using a Lyapunov-based inner-loop controller and usesan outer-loop controller based on optimal control theory to recover the aircraft attitude, flightpath angle and airspeed while minimising the altitude loss.The automatic flight envelope recovery is verified in simulation on the NASA Generic TransportModel (GTM), a wide-envelope aircraft model that is able to model the flight mechanicsof large transport aircraft in out-of-envelope conditions.

[发布机构] Stellenbosch University