Method for acquiring system eigenfunction and signal feature value

Abstract

A method for obtaining system characteristic functions and signal characteristic values ​​only in the case of response output, which belongs to the method of parameter identification in the field of dynamic testing. The method adopts the cross-spectral density function of each response point instead of the frequency response function to carry out time-frequency filtering and frequency-domain parameter identification, including step (1) calculating and analyzing the cross-spectral density function of different measurement output point signals; 2) Carry out non-orthogonal wavelet analysis and calculation in the time-frequency domain according to the cross-spectrum calculation results; (3) Find the time-frequency analysis coefficients by inverse Fourier transform; (4) Perform time-frequency filtering by adding a rectangular window; (5) Find the filtered The cross-spectrum of the output signal is used as a system function for identification; (6) Carry out curve fitting to obtain system parameters; this method can improve the identification accuracy of system parameters, can accurately identify modal parameters, is simple and convenient, and is suitable for Dynamic analysis, performance verification and fault diagnosis of large civil engineering facilities such as large complex mechanical equipment, high-rise buildings and bridges.

Description

Technical field [0001] The invention relates to a method for acquiring signal characteristics based on cross-spectrum functions and time-frequency filtering under the condition of only response output, and belongs to the field of dynamic testing and parameter identification. Background technique [0002] The problem of feature extraction with only output signal is the key technology of mechanical system, dynamic test and fault diagnosis technology under operating conditions. The biggest advantages of using environmental excitation as the vibration excitation source for the test for modal identification are: (1) It saves the cost and time of developing and installing special excitation devices; (2) It can excite all control surfaces at the same time, and simultaneously excite symmetry and opposition. It is called modal, eliminating the need for multiple tests; (3) greatly reducing the number and cycle of tests. [0003] It is inconvenient to use excitation equipment in dynamic ana...

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Problems solved by technology

[0003] It is inconvenient to use excitation equipment in the dynamic analysis, design performance verification and fault diagnosis of large and complex mechanical equipment, high-rise buildings, bridges and other large civil engineering facilities under operating conditions. Compared with other excitations (such as sweep frequency and pulse excitation), the environmental excitation intensity Weak, low signal-to-noise ratio, which greatly increases the dispersion of system parameter identification, and the feature extraction of the system is very difficult and greatly affected by noise

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