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Underdetermined system modal identification method based on automatic frequency band segmentation

A technology of frequency band division and underdetermined system, which is applied in the field of modal identification of underdetermined system based on automatic frequency band division, can solve the problem of reducing the accuracy of the sparse component analysis method, and achieve the effect of improving the accuracy

Active Publication Date: 2020-09-11
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the degree of underdetermination of the blind source separation system is large, it means that the number of available measurements is much smaller than the number of modes participating in the vibration, and the accuracy of the sparse component analysis method will decrease

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Taking a 10-story linear shear building model, the floor mass and interstory stiffness of each floor are 1000Kg and 1.76108N / m respectively; mass proportional damping is adopted, the damping coefficient is 2, and the maximum damping ratio is 1.5%. The first two structural responses are used for modal identification by imposing initial conditions to generate free vibration responses.

[0027] Based on the above conditions, this embodiment provides an underdetermined system mode identification method based on automatic frequency band segmentation, including the following steps:

[0028] The first step: convert the acceleration response to the time-frequency domain;

[0029] The response of the vibration system is transformed into the time-frequency domain by short-time Fourier transform. The expression in the time-frequency domain is In the formula, and Respectively is the response and the modal response Short-time Fourier transform at frequency ω at time t; ...

Embodiment 2

[0042]This embodiment provides a civil engineering structure health status monitoring system based on automatic frequency band segmentation, including a remote server and an acceleration sensor for collecting acceleration data arranged on the main part of the civil engineering structure; the acceleration sensor may include a controller, GPS Module, thermometer, accelerometer, gyroscope, 3D compass, wireless transceiver and power module, the controller is connected to the wireless transceiver, accelerometer and power module respectively, and the GPS module, thermometer, gyroscope and 3D compass are connected to the accelerometer ; The acceleration sensor is connected to the remote server through a wired or wireless method, and the acceleration data collected by the acceleration sensor is transmitted to the remote server for mode recognition.

[0043] The remote server is used to perform the following steps:

[0044] The first step: convert the acceleration response to the time-...

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Abstract

The invention belongs to the technical field of civil engineering structure health monitoring data analysis, and particularly provides an underdetermined system modal identification method based on automatic frequency band segmentation. According to the method, the response of a vibration system is transformed into a time-frequency domain through short-time Fourier transform; therefore, the windowlength of the short-time Fourier is adaptively determined by utilizing the information entropy; a minimum value of a frequency spectrum is automatically searched according to a scale space peak detection method; the subsection points are determined as subsection points in a frequency range; then, a single-mode point on a time-frequency plane is detected in each frequency sub-band; according to the method, single-mode points are clustered to obtain a vibration mode matrix, because the number of measurements in each frequency sub-band is greater than the number of active modes, a time domain modal response is obtained through short-time inverse Fourier transform, and finally, a logarithm attenuation technology can be utilized to estimate the frequency and the damping ratio; according to themethod, the segmentation points on the frequency axis are automatically positioned, and sparse component analysis is used in the sub-bands, so that the segmentation points can be accurately identified under the condition that the underdetermined degree is relatively high.

Description

technical field [0001] The invention belongs to the technical field of civil engineering structure health monitoring data analysis, and relates to a mode recognition method in the case of a large degree of underdetermination, in particular to an underdetermined system mode recognition method based on automatic frequency band segmentation. Background technique [0002] Modal parameters include modal frequency, mode shape and damping ratio, which are important parameters to characterize the dynamic characteristics of civil engineering structures. The process of identifying modal parameters from vibration data is consistent with the principle of blind source separation method, so the modal identification method based on blind source separation theory came into being. The number of active modes of actual structures is often unknown, and the number of sensors may be limited, so the method of underdetermined blind source separation is suitable for mode identification of large stru...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06K9/00
CPCG06F2218/04G06F2218/08G06F2218/12Y02T90/00
Inventor 姚小俊杨欣赵少伟
Owner HEBEI UNIV OF TECH