Search

This paper presents a flight envelope protection system for NASA’s Transport Class Model. The developed protection scheme is based on a command-limiting architecture that accounts for aircraft adverse aerodynamics, unusual attitude, and structural integrity and is designed to augment a standard gain-scheduled flight control law. The scheme also includes an energy protection system, which relies on an automatic throttle control loop that implements a total energy control law. In the setup adopted, the limits of the protected envelopes are actively adjusted to ensure, on the one hand, that the aircraft always stays in a safe flight condition and, on the other hand, that the pilot has enough control authority to perform aggressive maneuvers, if needed. Batch simulations demonstrate the efficacy of the protection system in maintaining the aircraft within desired safe conditions.

Reference tracking and vibration suppression are typical goals in motion control systems. Standard feedforward methods to achieve these goals are inversion-based feedforward control and input shaping. The former achieves perfect tracking but lacks robustness to uncertainties in the system dynamics while the latter may account for robustness at the expense of reduced tracking performance. In this work, a continuous time finite-impulse-response (FIR) prefilter design for linear systems is proposed which allows to trade off tracking performance against robustness. The approach is based on a finite time linear quadratic (LQ) optimal control formulation of the filtering task. Robustness is taken into account by penalizing large magnitudes of the trajectory sensitivity. Tracking delay can be reduced by adjusting the filter length which is a free design parameter. With the proposed prefiltering scheme fast and robust tracking can be achieved. An important application is simultaneous tracking and vibration suppression for motion systems with uncertain elasticity parameters which is used as a simulation example.

In an effort to improve the overall safety of the current and future air transportation system, researchers have been investigating the causes and series of events that can potentially lead to aircraft loss of control (LoC) as well as methods to prevent the occurrence of such events. Motivated by this challenging problem, this paper presents preliminary work on the development of technologies for in-flight LoC prediction and prevention. The developed scheme is based on a quantitative approach for LoC characterization introduced by the Boeing Company and NASA Langley Research Center, and is designed to arrest the development of an LoC sequence through an integrated LoC prediction and prevention control system. The paper also presents initial piloted simulations that analyze the ability of the developed system to assist the pilot in flying the aircraft through adverse environmental conditions, and to preserve safe aircraft operation by preventing erroneous crew input that could potentially lead to an LoC situation.

Motivated by the problem of loss-of-control prevention, this paper presents a dynamic flight envelope protection system for NASA’s Transport Class Model. The developed protection scheme is based on a command-limiting approach that accounts for aircraft adverse aerodynamics, unusual attitude, and structural integrity, and is implemented around a standard gain-scheduled flight control law. The scheme also includes an energy protection scheme, which relies on an automatic throttle control system that implements a total energy control law. Preliminary batch and pilot-in-the-loop simulations demonstrate the efficacy of the protection system in maintaining the aircraft within desired safe conditions, without limiting the ability of the pilot to perform aggressive, evasive maneuvers.