Uncertainty bounds on modal parameters obtained from stochastic subspace identification

• Published in: Mechanical systems and signal processing Vol. 22; no. 4; pp. 948 - 969
• Main Authors: Reynders, Edwin, Pintelon, Rik, De Roeck, Guido
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.05.2008; Elsevier
• Subjects: Civil engineering structures; Covariance analysis; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Measurement and testing methods; Mechanical systems; Operational modal analysis; Physics; Solid mechanics; Structural and continuum mechanics; Subspace methods; System identification; Uncertainty bounds; Civil engineering structures; Covariance analysis; Operational modal analysis; System identification; Uncertainty bounds; Mechanical systems; Subspace methods; Removal; Uncertainty; Modal analysis; Error estimation; Stabilization; Bias; Vibration measurement; Vibration test; Vibrometer; Variance; Uncertain system; Model matching; Covariance; Civil engineering; Probabilistic approach; Subspace method; Mechanical system; Signal processing
• ISSN: 0888-3270; 1096-1216
• DOI: 10.1016/j.ymssp.2007.10.009

The modal parameters of a structure that are estimated from ambient vibration measurements are always subject to bias and variance errors. In this paper, it is discussed how part of the bias errors can be removed and how the variance errors can be estimated from a single ambient vibration test. The bias removal procedure makes use of a stabilization diagram. The variance estimation procedure uses the first-order sensitivity of the modal parameter estimates to perturbations of the measured output-only data. This methodology, that is generally applicable, is illustrated here for the reference-based covariance-driven stochastic subspace identification algorithm. Both simulated and measured vibration data are used to demonstrate the accuracy and practicability of the derived expressions.