System and method for testing structure mode of vibration based on digital image recognition

Patent metadata

Field	Value
Publication number	US-12130209-B2
Application number	US-202117524750-A
Country	US
Kind code	B2
Filing date	Nov 12, 2021
Priority date	May 28, 2020
Publication date	Oct 29, 2024
Grant date	Oct 29, 2024

Abstract

Disclosed is a system and method for testing a structure mode of vibration based on digital image recognition, which comprises a camera, targets, a bridge, a vertical acceleration sensor and a lateral acceleration sensor; the camera is arranged near the bridge head of the bridge; the bridge is equipped with a plurality of targets equidistantly inside guardrails on both sides; and the vertical acceleration sensor and the lateral acceleration sensor are fixedly arranged on the camera. The present application avoids the arrangement of a large number of sensors and complicated wiring in the bridge vibration detection, saves time and reduces economic cost, is convenient to operate, has relatively high precision, and has broad application prospects.

First claim

What is claimed is:

1. A method for testing a structure mode of vibration based on digital image recognition, being performed by a system for testing a structure mode of vibration based on digital image recognition including a camera ( 1 ), targets ( 2 ), a bridge ( 3 ), a vertical acceleration sensor ( 4 ) and a lateral acceleration sensor ( 5 ), where the camera ( 1 ) is arranged near a bridge head of the bridge ( 3 ), the bridge is equipped with a plurality of targets ( 2 ) equidistantly inside guardrails on both sides, and the vertical acceleration sensor ( 4 ) and the lateral acceleration sensor ( 5 ) are fixedly arranged on the camera ( 1 ), comprising the following process that:
the camera ( 1 ) captures images containing all targets ( 2 ) in real time, and the vertical acceleration sensor ( 4 ) and the lateral acceleration sensor ( 5 ) monitor the vibration of the camera ( 1 ) itself in real time; and
when the bridge ( 3 ) is subjected to random excitation to produce vibration, the targets ( 2 ) and the camera ( 1 ) vibrate together with the bridge ( 3 ), and the lateral vibration curve, longitudinal vibration curve and torsional vibration curve of the bridge ( 3 ) are calculated by the images containing the targets ( 2 ) and the camera ( 1 ) vibration information to realize the testing of bridge ( 3 ) vibration,
wherein the process of calculating the lateral vibration curve, longitudinal vibration curve and torsional vibration curve of the bridge ( 3 ) by the images containing the targets ( 2 ) and the camera ( 1 ) vibration information comprises:
capturing the center of each target ( 2 ) from the images containing the targets ( 2 ), obtaining the pixel displacements of the target ( 2 ) center at different moments, and converting into a unit of length, and then obtaining the lateral relative vibration displacements and longitudinal relative vibration displacements of the measuring points where the targets are located;
unifying the units of the lateral relative vibration displacement and longitudinal relative vibration displacement of each target ( 2 ) and the units of the lateral relative vibration displacement and longitudinal vibration displacement unit of the camera ( 1 ), and subtracting the reverse displacement caused by camera vibration from the relative vibration displacement of the measuring point to obtain the absolute vibration displacement of the measuring point;
drawing a lateral time history curve and a vertical time history curve of the measuring point corresponding to each target;
using the lateral time history curve and the longitudinal time history curve of the measuring point corresponding to each target to obtain the natural frequency of each order, and obtain the lateral vibration amplitude-frequency characteristics and longitudinal vibration amplitude-frequency characteristics of the bridge ( 3 );
calculating the real-time torsion angle of the measuring point and drawing a time history curve through the longitudinal absolute vibration displacements of measuring points of the two lateral targets ( 2 ) in the longitudinal direction of the bridge ( 3 ), and obtaining the torsion amplitude-frequency characteristic curve of each measuring point by using the real-time torsion angles and time history curves of all measuring points; and
using the obtained torsion amplitude-frequency characteristic curve of each measuring point to obtain the lateral vibration curve, longitudinal vibration curve and torsional vibration curve of the bridge ( 3 ).

2. The method for testing the structure mode of vibration based on digital image recognition according to claim 1 , performing denoising preprocessing on the absolute vibration displacement data of the measuring point corresponding to each target by filtering, and drawing the lateral time history curve and longitudinal time history curve of the measuring point corresponding to each target.

3. The method for testing the structure mode of vibration based on digital image recognition according to claim 1 , performing the fast Fourier transform and spectrum analysis on the lateral time history curve and longitudinal time history curve of the measuring point corresponding to each target to identify the natural frequency of each order, and obtain the lateral vibration amplitude-frequency characteristic and longitudinal vibration amplitude-frequency characteristic of the bridge ( 3 ).

4. The method for testing the structure mode of vibration based on digital image recognition according to claim 1 , after calculating the real-time torsion angle of the measuring point and drawing the time history curves, performing the fast Fourier transform and frequency spectrum analysis on the time history curves, and performing the same processing on the data of the measuring points corresponding to all targets to obtain the torsional amplitude-frequency characteristic curve of each measuring point.

5. The method for testing the structure mode of vibration based on digital image recognition according to claim 1 , using the obtained amplitude-frequency characteristic curve of each measuring point, calculating the damping coefficient based on a half-power spectral density method, calculating the impact coefficient of the bridge by a weighting method, and drawing the lateral vibration curve, longitudinal vibration curve and torsional vibration curve of the bridge ( 3 ).

Assignees

• Changan Univ

Inventors

• Zhou Yongjun
• Zhao Yu
• Wang Yelu
• Han Yi
• Jing Yuan
• Xue Yuxin
• Li Ranran

Classifications

• G01H9/002

  for representing acoustic field distribution (sonar systems for imaging G01S7/56, G01S15/89; acoustic holography G03H3/00) · CPC title

• G01H9/00

  Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means · CPC title

• G01M11/081

  by using a contact-less detection method, i.e. with a camera · CPC title

• G01M5/0008

  of bridges · CPC title

• G01M7/025

  Measuring arrangements · CPC title