Research On Method For Operational Modal Parameter Identification Based On Independent Component Analysis

Modal parameters extraction of the mechanical structure is the basis for the mechanical structure dynamic analysis. The experimental modal method and the operational modal method are commonly used to extracting modal parameter. The structure need external excitation by using the experimental modal analysis, which is extremely difficult in operation of large and complex mechanical systems. Operational modal analysis (OMA) is without additional excitation. This is only relied on the state response signal to extract structure modal parameters of the mechanical structure and more close to actual situation. However, for assuming system suffered load of the white noise in OMA, which does not match with actual situation, the method leads to greater error results.Recently, independent component analysis (ICA) of the Blind signal processing was widely used in the project application in blind source separation (BSS).This article dissected the ICA basic algorithm principle after reviewing the OMA theory and method, discovering the close relation between them. On the basis of the explanation of the ICA base-vector mode meaning, this article proposed the mode parameter identification with the ICA algorithm in the mechanical structure dynamic analysis, discussed the consistency between the ICA computation mode and the mechanical vibration mode, which provided theoretical basis by using ICA in the mechanical structure dynamic analysis.Through computer numeral simulation and laboratory physical analogue, this article dissected analysis rationale, algorithm realization of ICA technology in mechanical dynamics, and the compatibility to different excitation and noise background. In order to weigh the separation effect, it put forward the concept of independent performance index. With the aid of the model response data of three degree of freedom spring quality system, the ICA numeral simulation results indicated that, the ICA separation mode frequency and the structure natural frequency coincidenced completely.This article had attempted to research continuous system model of the cantilever beam under various excitations, various niose levers and various data amounts of response. In the laboratory with the hammering , the reliable mode frequency and mode shape of cantilever beam was obtained. Using the OMA software of B & K and the self- developed ICA software, we had respectively carried on the mode parameter identification to acceleration response signal of the experimental facility. The results indicated that the ICA in three algorithms JADE, MSNR, GOSA can be extracted to structure mode, which had a good consistency with the modal parameters from the OMA. MSNR algorithm is superior to GOSA and JADE algorithm. Comparing with the OMA, the ICA algorithm is better in separation and adaptability, especially for short data.Based on the research of the theory and experimentation, we applied the method of identifying parameter on basis of the ICA to dynamic design of the stacking crane in automated warehouse. We also get the modal parameters of stacking crane along with the OMA software, and enhanced the reliability of the modal parameters by eliminating the false parameter. It' s the basis of dynamic design of the stacking crane.