MIMO LMS-ARMAX IDENTIFICATION OF VIBRATING STRUCTURES—PART I: THE METHOD

✍ Scribed by S.D. FASSOIS

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 365 KB
• Volume: 15
• Category: Article
• ISSN: 0888-3270
• DOI: 10.1006/mssp.2000.1382

✦ Synopsis

A comprehensive linear multi stage autoregressive moving average with exogenous excitation (LMS-ARMAX) method for e!ective multiple-input multiple-output (MIMO) structural dynamics identi"cation in the presence of noise is introduced. The method consists of (a) a vector ARMAX representation of an appropriate form, (b) e!ective LMS parameter estimation, (c) statistical order selection/validation, and (d) a digital dispersion analysis (DA) methodology for e!ective modal characterization. The LMS-ARMAX method overcomes many of the di$culties that had rendered MIMO ARMAX identi"cation di$cult in the past, featuring modest computational complexity, high accuracy, guaranteed algorithmic and model stability, and thus applicability to higher-dimensional problems and lightly damped structures, accurate modal parameter extraction, and e!ective distinction of structural from &extraneous' modes. A critical assessment of the LMS-ARMAX method under various noise conditions, as well as comparisons with a simpler ARX version and the ERA (Eigensystem Realization Algorithm), are undertaken based upon experimental vibration data obtained from a scale aircraft skeleton structure. The paper is divided into two parts: The LMS-ARMAX method is presented in the "rst, and its critical assessment and comparisons in the second.