Robotization in fruit grading system

A grading robot system, which automatically provides fruits from containers and inspects all sides of the fruits was developed. The robot system consists of two fruit providing robots and a grading robot. Both robots had 3 DOF Cartesian coordinate manipulators, and 12 suction pads as end-effectors for transporting fruits. The grading robot had 12 color TV cameras, and 28 lighting devices as a machine vision system. The grading robot sucked 12 fruits up at a time and 12 bottom images of all the fruits were acquired during the manipulator moving from a halfway stage to carriers on a conveyor line. Before releasing the fruits to the carriers, 4 side images of each fruit were acquired by rotating the suction pads for 270°. The stroke of the manipulators was about 1.2 m and it took about 4.3 s to move back to the initial position that meant that this robot could grade three fruits per second. This grading robot system made following effects: (1) Labor substitution, (2) Objective grading operation without human subjective judgment, (3) Data accumulation on fruit grading for traceability and farming guidance to producer.