IMPROVED COVARIANCE DRIVEN BLIND SUBSPACE IDENTIFICATION METHOD

• Published in: Chinese journal of mechanical engineering Vol. 19; no. 4; pp. 548 - 553
• Main Author: ZHANG, Zhiyi
• Format: Journal Article
• Language: English
• Published: State Key Laboratory of Vibration, Shock and Noise, Shanghai Jiaotong University, Shanghai 200240, China 2006
• Subjects: 信号组分; 元件阻抗误差; 子空间; 时频; 机械精确度; 稳定性; Hankel matrix; Weak modes; Component energy index (CEI); Stabilization diagram; Subspace identification method
• ISSN: 1000-9345; 2192-8258
• DOI: 10.3901/cjme.2006.04.548

An improved covariance driven subspace identification method is presented to identify the weakly excited modes. In this method, the traditional Hankel matrix is replaced by a reformed one to enhance the identifiability of weak characteristics. The robustness of eigenparameter estimation to noise contamination is reinforced by the improved Hankel matrix, in combination with component energy index （CEI） which indicates the vibration intensity of signal components, an alternative stabilization diagram is adopted to effectively separate spurious and physical modes. Simulation of a vibration system of multiple-degree-of-freedom and experiment of a frame structure subject to wind excitation are presented to demonstrate the improvement of the proposed blind method. The performance of this blind method is assessed in terms of its capability in extracting the weak modes as well as the accuracy of estimated parameters. The results have shown that the proposed blind method gives a better estimation of the weak modes from response signals of small signal to noise ratio （SNR）and gives a reliable separation of spurious and physical estimates.