INVESTIGATION OF THE MAXIMUM FREQUENCY THAT CAN BE DETERMINED WITH THE NIKON P900 VIDEO CAMERA

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Eren M.

1st International Conference on Frontiers in Academic Research, Konya, Türkiye, 18 - 21 Şubat 2023, cilt.1, ss.154

  • Yayın Türü: Bildiri / Özet Bildiri
  • Cilt numarası: 1
  • Basıldığı Şehir: Konya
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.154
  • Yıldız Teknik Üniversitesi Adresli: Evet

Özet

Structural health monitoring is essential to determine the structure's reaction to the loads it is exposed to and to predict possible structural damage. Many measuring devices, from accelerometers to video cameras, are used to determine the dynamics of the building. This study aims to extract the movements of the shaking table at different frequencies with the video camera and investigate the maximum frequency the camera can detect. In this context, 50 FPS video recordings of the handmade mini shaking table movement were made with a Nikon brand and P900 model camera (83x optical zoom). The speed of the shaking table can be increased or decreased with the help of the control. Recordings were obtained by increasing the frequency at intervals of about 2 minutes (3.125, 5.029, 9.277 and 13.75 Hz). The displacement data was obtained by data processing of the images in the MATLAB 2018b software, and the frequency values were calculated by performing the FFT analysis in the MATLAB 2018b software. It was seen that these values were compatible with the frequency values set by the control. However, according to the Nyquist sampling frequency, the video camera had problems capturing 13.75 Hz motion when it should have captured 25 Hz. In the examination, it was observed that the contrast of the video frames decreased depending on the speed. There was a problem in determining the movements during the data processing phase. It is foreseen that this problem will be solved by processing the image of the parts with lower linear velocity in the fixed parts caused by the moving part of the shaking table. In data processing, the frequency of 13.75 Hz could be determined with the help of the image taken from the points mentioned above. This experiment revealed that the camera could detect higher frequencies with the image taken from regions with lower linear velocity for measurement; the maximum frequency it can measure in the moving part of the shaking table is 10 Hz.