Acquiring system eigenfunction and signal feature value method

Abstract

A method of catching systematic eigenfunctions and signal eigenvalues under the condition of only response output available belongs to the parametric recognition technique in dynamic test field. The technique is a method of adopting cross spectral density functions of each response point instead of frequency response functions to perform time-frequency filtering and the parametric recognition of frequency domain, and includes the following steps: (1) carrying out analytic calculation of the cross spectral density functions of different metering signal of output points; (2) analyzing and calculating the nonorthogonal wavelets in the time-frequency domain according to the cross spectral calculating result; (3) inversing the fourier transformation to gain the time-frequency analyse coefficient; (4) adding a rectangular window to perform the time-frequency filtering; (5) calculating the cross spectrum of the output signal after filtering as the systematic function for recognition; (6) performing curvefitting to obtain the systematic parameter; the technique improves the recognition precision of the systematic parameters, precisely recognizes modal parameters, is simple and convenient, and is suitable for the dynamic analyses, the performance verification and the failure diagnosis of large civil engineering establishments such as large and complex mechanical equipments under operation status, high-rise buildings, bridges, etc.

Description

technical field [0001] The invention relates to a method for acquiring signal features based on cross-spectrum function and time-frequency filtering under the condition of only response output, which belongs to the field of dynamic testing and parameter identification. Background technique [0002] The problem of feature extraction with only output signals is a key technique for mechanical systems under operating conditions, dynamic testing and fault diagnosis techniques. The biggest advantages of using environmental excitation as the vibration excitation source of the test for modal identification are: (1) saving the cost and time of developing and installing special excitation devices; (2) all control surfaces can be excited at the same time, and symmetrical and opposing It is called the modal, eliminating the need for multiple tests; (3) greatly reducing the number of tests and cycles. [0003] It is inconvenient to use excitation equipment in the dynamic analysis, desig...

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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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