Database Building and Interpolation for an Online Safe Flight Envelope Prediction System

Abstract

A study addresses offline construction of the database. The main focus and contribution of this study are database building and interpolation for the Database-Driven Safe Flight Envelope Prediction System (DEFEND) system. More importantly, through complexity analysis, the database approach is shown to be feasible for onboard real-time implementation within the aircraft control laws. Reachability analysis as the method to compute safe flight envelopes, as the theory provides a set-valued insight into safety and control design of dynamic systems. One advantage of this method is that all possible trajectories can be computed from all available control strategies and initial states, which naturally meets the safety guarantees. The computed results are called reachable sets, which are defined as a set of states that reach a certain target set within a certain time horizon and current control authority. Two sets of envelopes are computed using the level-set method toolbox. One is the pitching envelope, referred to the motion in the longitudinal plane with horizontal tail damage. The other is the rolling envelope, referred to the motion in the lateral plane with wing tip loss.