Vision-based Calibration Line and Liquid Level Detection Method for Volumetric Flasks

Aiming at the defects of the traditional method of volumetric flasks constant volume, which is caused by human-induced uncontrollable factors and leads to large error and low efficiency, designs a vision-based algorithm of volumetric flask calibration line detection and liquid level detection. In the calibration line detection stage, an improved Canny algorithm is proposed for edge detection, and the position of the calibration line is extracted by detecting the horizontal straight line through Hough transform. In the liquid level detection stage, binarization and morphological processing are used to remove the noise interference, and the liquid level is identified through connectivity domain analysis; finally, the position matching between the liquid level and the calibration line is used to determine whether the constant volume is completed or not. The experimental results show that the proposed method has high accuracy and efficiency of constant volume, the absolute error of constant volume is within ±0.04 ml, 95.33% of which is within ±0.02 ml, and it can realize the automatic high-precision constant volume of volumetric flasks.