Design, construction and evaluation of an automatic apple grading system

A system was designed and fabricated to grade apple automatically based on their size using machine vision. The system included several unites to single out, orient and grade apple. A cylinder container with circular hole in bottom which was equipped with agitator was built to single out the apple. This mechanism delivered apple to orientation unit, one by one. Two wooden rails with a specific form which was located on the ramp via adequate slope was used to orient the apple during rolling. After the orientation, apple were placed below the camera to take its photo. The photos were transferred to computer for image processing to determine the apple grade based on their size. A belt conveyor carries the apples and set them in appropriate place regard to their grade. As a final point, the wind spray valve is opened and the apple is pushed to the marked box. In order to evaluate the constructed system, 10 red and golden delicious apples of each grade were chosen and the completely randomized design test was conducted. The results demonstrated that the most time consumed was related to image processing. Almost 85% of apples were properly oriented in the orientation unit and graded correctly. The overall system performance was appropriate. Thus, the system can be used to grade apple automatically