Design and manufacturing of prototype for orange grading using phototransistor

Fruits are usually graded according to their quality. Grading process is classifying fruits according to size, shape, weight, color and ripening stage. Due to the lack of the small grading machines to fit small farms and higher prices of large grading machines, therefore this study aimed to design, manufacture and evaluate of a prototype for orange grading based on the fruit dimensions. The prototype uses different successively operating components, such as phototransistors and actuators, each performing a specific task. The operating principle depends on the phototransistor, signal gathering and output circuit for distributing unit. When it works, the system receives digital signals produced by fruits that shadow the light from a phototransistor sensor during fruit measuring. After digital signals processed by the electronic circuit, every fruit's sizing level is deduced. Then, the system will output switch signals to open the sorting switches according to fruit size. The prototype was evaluated concerned with three control factors which were conveyor chain velocity, sphericity percentage of fruit and stopping time and the affected parameters were grading efficiency, damage percentage and productivity. The optimum grading efficiency (92.2%) and minimum damage percentage (7.1%) was obtained at 0.15 m/s chain velocity and 1.5 s stopping time. The consumed energy was 16.2 W.h. The total operating cost was 4.9 L.E/h.