WAVELET-PROCESSED FLIGHT DATA FOR ROBUST AEROSERVOELASTIC STABILITY MARGINS

Wavelet analysis for filtering and system identification is used to im prove the estimation of aeroservoelastic (ASE) stability margins. Comp utation of robust stability margins for stability boundary prediction depends on uncertainty descriptions derived from the test data for mod el validation. Nonideal test conditions, data acquisition errors, and signal processing algorithms cause uncertainty descriptions to be intr insically conservative. The conservatism of the robust stability margi ns is reduced with parametric and nonparametric time-frequency analysi s of flight data in the model validation process. Nonparametric wavele t processing of data is used to reduce the effects of external disturb ances and unmodeled dynamics. Parametric estimates of modal stability are also extracted using the wavelet transform. F-18 High Alpha Resear ch Vehicle ASE flight test data are used to demonstrate improved robus t stability prediction by extension of the stability boundary from wit hin the flight envelope to conditions sufficently beyond the actual fl ight regime. Stability within the flight envelope is confirmed by flig ht test. Practical aspects and guidelines for efficiency of these proc edures are presented for on-line implementation.