Wavelet-Processed Flight Data for Robust Aeroservoelastic Stability Margins

Abstract

Waveletanalysisfore lteringandsystem identie cationisusedto improvetheestimationofaeroservoelastic (ASE) stabilitymargins.Computationofrobuststabilitymarginsforstabilityboundarypredictiondependsonuncertainty descriptions derived from the test data for model validation. Nonideal test conditions, data acquisition errors, and signal processing algorithms cause uncertainty descriptions to be intrinsically conservative. The conservatism of the robust stability margins is reduced with parametric and nonparametric time-frequency analysis of e ight data in the model validation process. Nonparametric wavelet processing of data is used to reduce the effects of external disturbances and unmodeled dynamics. Parametric estimates of modal stability are also extracted using the wavelet transform. F-18 High Alpha Research Vehicle ASE e ight test data are used to demonstrate improved robust stability prediction by extension of the stability boundary from within the e ight envelope to conditions sufe cently beyond the actual e ight regime. Stability within the e ight envelope is cone rmed by e ight test. Practical aspects and guidelines for efe ciency of these procedures are presented for on-line implementation.