Fruit size determination by a new optical sensor

Resumen

A ring sensor system is being used to calibrate different kinds of fruit. The system consists of a feeding device –aligner- with two conveyor belts that convey the fruits to the optical sensor. The fruits are put on the aligner, and when they leave it, they cross the ring, which scans them, measuring length, volume and four diameters. Until now, the analysed parameter has been the maximum diameter of the largest cross section. In trials with models it has been proved that speed has no influence on that parameter. It has also been showed that the centered passing through the ring is not always the best option, but it depends on the object’s size. At fruit tests, it has been demonstrated that the best orientation is that carrying the fruits with their polar axis parallel to the line direction. Excellent results have been obtained at ‘Navelina’ orange -average coefficient of variation CV= 0.9% and average absolute error taken in absolute value |Ea|= 1.37 mmand ‘Primafiori’ lemon -average CV= 1.5% and average |Ea|= 1.12 mm-. Values not so good, although similar to those coming from a last generation computer vision system have been obtained on ‘Salustiana’ orange. Results with apples and tangerines are still pending to be analysed. The next step is to improve the feeding system, achieving a totally automated one with the fruits self-orientating, for commercial application.