CRITICAL ASSESSMENT OF MIMO STRUCTURAL IDENTIFICATION METHODS: ARX AND ARMAX SCHEMES

摘要

A critical assessment of a deterministic ARX and a stochastic ARMAX structural identification method is presented based upon MIMO vibration data obtained from a scale airplane structure. The two methods are shown to be capable of accurately identifying all excited structural modes, including a pair of very closely-spaced modes and a "local" tail bending mode. Damping levels, though low (ζ < 1%), are accurately estimated as well. Significant model over determination is nevertheless required. This is higher in the ARX case, and especially so in the presence of added noise. Issues of model order estimation, as well as distinction of structural from "extraneous" modes are also investigated.