Methodologies for Adaptive Flight Envelope Estimation and Protection

Abstract

This paper reports the latest development of several techniques for adaptive flight envelope estimation and protection system for aircraft under damage upset conditions. Through the integration of advanced fault detection algorithms, real-time system identification of the damage/faulted aircraft and flight envelop estimation, real-time decision support can be executed autonomously for improving damage tolerance and flight recoverability. Particularly, a bank of adaptive nonlinear fault detection and isolation estimators were developed for flight control actuator faults; a real-time system identification method was developed for assessing the dynamics and performance limitation of impaired aircraft; online learning neural networks were used to approximate selected aircraft dynamics which were then inverted to estimate command margins. As off-line training of network weights is not required, the method has the advantage of adapting to varying flight conditions and different vehicle configurations. The key benefit of the envelope estimation and protection system is that it allows the aircraft to fly close to its limit boundary by constantly updating the controller command limits during flight. The developed techniques were demonstrated on NASA's Generic Transport Model (GTM) simulation environments with simulated actuator faults. Simulation results and remarks on future work are presented.

Design and Piloted Simulator Evaluation of Adaptive Safe Flight Envelope Protection Algorithm

“…Boeing has a similar setup for flight A variety of methods for tackling this challenge have been investigated in previous studies. In [15], online learning neural networks are used to approximate selected aircraft dynamics which are then inverted to estimate command margins for limit avoidance. The goal of the approach in [16,17] is to provide the pilot aural, visual, and tactile cues focused on maintaining the pilot's control action within predicted loss-of-control boundaries.…”

Adaptive Backstepping Flight Control for Modern Fighter Aircraft

“…This statement has resulted in a whole new area of research, usually referred to as adaptive flight envelope estimation and/or protection, see e.g. [198,211]. It is possible to indicate to the pilot which axis have suffered a failure with the adaptive controllers developed in this thesis, so that he is made aware that there is a failure and that he should fly more carefully.…”

Optimal Control Framework for Estimating Autopilot Safety Margins

“…To estimate changes in the flight envelope is a non-trivial matter, and currently is an active area of research within the aeronautical community. The survey paper of Tang et al [15] summarizes some of the developments in adaptive flight envelope estimation. In general, the literature describes two different approaches for estimating the safe maneuvering envelope.…”