Optical flow tracking method for vibration identification of out-of-plane vision

Yu, Qibing; Yin, Aijun; Zhang, Quan; Ma, Shiyang

doi:10.21595/jve.2017.17771

Cited by 5 publications

(1 citation statement)

References 25 publications

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“…Ji and Chang 65 were able to use an optical flow method for the detection of small cable vibration by analyzing an image sequence of a vibrating cable segment captured by one single camera. Yu et al 66 were able to use the Lucas-Kanade optical flow method combined with a pinhole camera mode for detecting the transverse vibration of a cantilever beam. Due to advances in integrated-chip technology, high-speed cameras have much higher resolution and frame rates than ever before.…”

Section: Background Of Signal/image Processing For Vibration-based Da...mentioning

confidence: 99%

Vibration-based hidden damage imaging using stereo cameras with digital image correlation

Wang,

Abbott,

Fong

et al. 2023

Structural Health Monitoring

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This paper explores a full-field non-contact optical sensing technique using a stereo camera for imaging hidden damage based on vibration-based damage detection methodology in structural health monitoring. The technique utilizes a pair of digital cameras to capture dynamic operational deflection shapes (ODSs) over the region of interest (ROI) of a structure’s surface via digital image correlation (DIC) when subjected to vibrational excitation. This research overcomes bottlenecks in using high vibration modes for imaging the hidden damage area by (1) applying DIC to operational modal analysis with simple pick-peaking techniques to gather natural frequencies and operational mode shapes in plate structures, while (2) using wavelet analysis to reveal the image of the damage region as a means for baseline-free global damage quantification. In the feasibility study, four cases with two aluminum plates with large damage regions were investigated with a vibration shaker generating a frequency sweep up to 1 kHz. The stereo camera imaged the speckled surface of the plate with white light. Once the dynamic ODSs in the ROI were observed using DIC, the natural frequencies and associated operational mode shapes were extracted using a peak-picking technique in the frequency spectrum. Natural frequencies and operational mode shapes from finite element analysis correlated well with the experimental observations from three-dimensional DIC for all 12 vibration modes respectively. A wavelet transform mode shape curvature (WT-MSC) technique to obtain the modal shape curvature via a two-dimensional continuous wavelet transform with a Mexican Hat analyzing wavelet was then implemented on each of the first 12 vibration mode shapes. A damage image condition that incorporates all weighted wavelet coefficients is proposed to image the damage region. The hidden damage was visualized clearly with WT-MSC, as the technique is much less sensitive to noise than the use of MSC alone, and the use of high vibration modes exhibiting larger mode shape curvatures provided a greater sensitivity for imaging the damage region. Hidden damage regions were successfully visualized in all four cases.

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Section: Background Of Signal/image Processing For Vibration-based Da...mentioning

confidence: 99%

Vibration-based hidden damage imaging using stereo cameras with digital image correlation

Wang,

Abbott,

Fong

et al. 2023

Structural Health Monitoring

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Synchronous monitoring of axial vibration and rotation speed of rotating cylinder by linear array scanning

Deng

Zhang

et al. 2022

Mechanical Systems and Signal Processing

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Vision vibration measurement based on coded illumination in a single frame

Zhang

Liang

et al. 2021

J. Opt. Soc. Am. B

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A vision-based mechanical vibration measurement method is presented and verified by experiments in this paper. The coded illumination is projected on the objects by a digital light processing projector with a digital micromirror device in it. The projection patterns are designed to be concentric. In one integration time of the camera, the projector is exposed several times, which embeds temporal information in the images. A single frame can be divided into subframes by separating the coded concentric patterns. The centroids of the coded concentric patterns are fitted, and the centroids are treated as virtual feature points with vibration information. The acquisition devices are common low-speed cameras, and they record the vibration whose frequency exceeds the camera frame rate. The temporal resolution is increased by 10 times, corresponding to the 400 Hz sampling frequency in the experiment. We can measure the vibration of multiple points with different sampling frequencies. The frequency measurement accuracy is in the subhertz level in low-frequency measurement, relative error is always slightly greater than 0.01 in high-frequency measurement, and the amplitude resolution is 130 µm.

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Optical flow tracking method for vibration identification of out-of-plane vision

Cited by 5 publications

References 25 publications

Vibration-based hidden damage imaging using stereo cameras with digital image correlation

Vibration-based hidden damage imaging using stereo cameras with digital image correlation

Synchronous monitoring of axial vibration and rotation speed of rotating cylinder by linear array scanning

Vision vibration measurement based on coded illumination in a single frame

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