Visual feedback guidance of manipulator for eggplant [Solanum melongena] harvesting using fuzzy logic

This study was conducted as a first step in the development of the robotic harvesting system for eggplants. The robotic harvesting system with hand-eye structure was fabricated and the visual feedback fuzzy control model to operate the manipulator was developed. The control model was examined in terms of manipulator guidance to the fruit, estimation of the fruit maximal diameter for selective harvesting and estimation of the fruit angle for the picking movement. From the results of the approach experiment, the control model enabled the manipulator end to reach a fruit 300 mm away with 6 to 10 feedback signals. The manipulator trajectory varied in vertical direction with fruit location and the control model actuated the manipulator end slightly upward than the target region. The control model could estimate the fruit maximal diameter with an accuracy of 29.0±17.9%. However, it still has a low standard of performance as a visual sensor for selective harvesting. Moreover, it could estimate the fruit angle in row direction with an error of 3.6±2.60. The visual feedback guidance ot the manipulator was confirmed to be an effective method for a robotic eggplant harvesting.