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Sensors 2012, 12(10), 13871-13898; doi:10.3390/s121013871
Article

Frequency Identification of Vibration Signals Using Video Camera Image Data

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Received: 22 August 2012; in revised form: 4 October 2012 / Accepted: 10 October 2012 / Published: 16 October 2012
(This article belongs to the Section Physical Sensors)
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Abstract: This study showed that an image data acquisition system connecting a high-speed camera or webcam to a notebook or personal computer (PC) can precisely capture most dominant modes of vibration signal, but may involve the non-physical modes induced by the insufficient frame rates. Using a simple model, frequencies of these modes are properly predicted and excluded. Two experimental designs, which involve using an LED light source and a vibration exciter, are proposed to demonstrate the performance. First, the original gray-level resolution of a video camera from, for instance, 0 to 256 levels, was enhanced by summing gray-level data of all pixels in a small region around the point of interest. The image signal was further enhanced by attaching a white paper sheet marked with a black line on the surface of the vibration system in operation to increase the gray-level resolution. Experimental results showed that the Prosilica CV640C CMOS high-speed camera has the critical frequency of inducing the false mode at 60 Hz, whereas that of the webcam is 7.8 Hz. Several factors were proven to have the effect of partially suppressing the non-physical modes, but they cannot eliminate them completely. Two examples, the prominent vibration modes of which are less than the associated critical frequencies, are examined to demonstrate the performances of the proposed systems. In general, the experimental data show that the non-contact type image data acquisition systems are potential tools for collecting the low-frequency vibration signal of a system.
Keywords: image data acquisition; vibration signal; insufficient frame rate; time frequency analysis image data acquisition; vibration signal; insufficient frame rate; time frequency analysis
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Jeng, Y.-N.; Wu, C.-H. Frequency Identification of Vibration Signals Using Video Camera Image Data. Sensors 2012, 12, 13871-13898.

AMA Style

Jeng Y-N, Wu C-H. Frequency Identification of Vibration Signals Using Video Camera Image Data. Sensors. 2012; 12(10):13871-13898.

Chicago/Turabian Style

Jeng, Yih-Nen; Wu, Chia-Hung. 2012. "Frequency Identification of Vibration Signals Using Video Camera Image Data." Sensors 12, no. 10: 13871-13898.



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