Liquid level measurement and control in dark environments with computer vision-based phosphorescent marking method

The main purpose of this study is to perform liquid level measurement control processes of experimental liquid flow systems used in chemistry, agriculture and biology using computer vision. Within the scope of the purpose, a laboratory type liquid flow system consisting of storage liquid tanks, process tank, pumps, camera and electronic circuits was designed. The system was used to measure liquid level and pump flow rates in bright and dark environments. Liquid temperature data was converted to visible light and the data was captured by the camera. Image analysis, measurement and control software for liquid processes was developed. In level measurements made in bright environments, distorting effects such as light reflection, parallax effect and liquid stains in the images caused erroneous measurements. A new method was proposed to reduce these effects. The method is to mark the liquid surface in the dark using a phosphorescent float. Before the measurement, the float, which is stimulated with UV light for 5 seconds, glows in the dark and is detected by the camera for 120 seconds. The level and volume of the liquid were measured by determining the location of the glow with computer vision. The liquid level was measured using the RGB color space of the image, line profile and thresholding operations. The measurement results were compared with the actual measurement results and the measurement error was calculated as ±3 mm and the accuracy was %98.23. Using the method, a mixing process of two different liquids at certain rates was applied. The method simplified the complex image processing algorithms and mathematical operations in liquid level detection. It facilitates the development processes of FPGA or microcontroller-based software using image processing techniques in liquid level measurement. It is a low-cost and easy-to-implement measurement method. It has a wide application potential in laboratory processes for the purpose of monitoring and controlling liquid level changes.