Development of Sensor-based Automatic Colour Sorting System for Tomato

The present study was aimed to develop an automatic colour sorting apparatus for tomatoes by utilizing a microcontroller, colour sensor array, servo motors, and mechanical components. When an object was passed through the sensing region of the colour sorting system, a colour sensor array sent input signals, attenuation level of colours to a processing unit/microcontroller Arduino board. Further, the output signal (colour frequency) of microcontroller was sent to an actuator (servo motor) for sorting coloured objects into separate collecting pans. The process algorithm was programmed in Arduino IDE software. The detected colour frequencies were expressed in red, green, and blue on an LCD and computer screen along with the colour of the respective samples. The developed system was initially tested with six distinct coloured balls of 70 mm diameter, and calibrated at three different lighting conditions of a lit room, dark room, and daylight. Subsequently, tomatoes of 41.97–56.57 mm geometric mean diameter of three different colours, i.e., red, pink, and green, were used for automatic sorting. The system automatically separated tomatoes of a particular colour into three subclasses of large, medium, and small as per their colour values. Under all lighting conditions, the automatic sorting system precisely separated 1,800 sample.h-1.