7/6/2023 0 Comments Pixel check mail frequency![]() ![]() In this study, the vibration signal of a system in operation was obtained from the images in an entirely distinct manner. Most of these works considered the spatial details of the images. Because the image signal closely relates to human eyes, numerous related studies can be easily accessed on the Internet. This is another work that proposes using image devices for practical applications. In a previous paper, we proposed such a system using an electret condenser microphone. Thus, there is potential to develop a data acquisition system using a notebook or PC and one of these peripheral devices as a sensor. Because all such peripheral devices are mass produced, they are often cheap yet still offer high quality. In addition, low-level high-speed digital video cameras with a price and frame speed of less than US$3,000 and 300 FPS, respectively, are also common products. 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.īecause of the rapid development of Web sites and computer software and hardware, peripheral devices such as electret condenser microphones and webcams are becoming increasingly popular. 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. Several factors were proven to have the effect of partially suppressing the non-physical modes, but they cannot eliminate them completely. 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. 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. 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. Two experimental designs, which involve using an LED light source and a vibration exciter, are proposed to demonstrate the performance. Using a simple model, frequencies of these modes are properly predicted and excluded. 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. ![]()
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