Effect of Fruit Location on Apple Detachment with Mechanical Shaking

Apples are picked manually every year around the world presenting challenges due to uncertain availability and the high cost of labor-force. To reduce dependence on seasonal labor and minimize harvest costs, shake-and-catch harvesting methods have been investigated in the past. However, these methods are ineffective in removing sufficient percentage of fruit from the trees, primarily due to the insufficient level of energy transferred to the desired branch locations. The primary goal of this study was to investigate the efficiency in detaching fruit from different locations of tree limbs. A fruit location index was formulated in this study to identify the location of targeted apples on a limb. A dynamic test system was developed to measure the dynamic response of fruit under certain shaking modes. From the experiment, fruit acceleration was found to be larger than 5 g when fruit location index was smaller than 2.5. It was also found the fruit (“Envy” variety) could generally be detached when the acceleration was higher than 5 g within the first 5 s shaking. Two harvesting tests (one on “Envy” variety, the other one on “Pink Lady” variety) were also conducted to verify the dynamic test results. The results showed that the majority of unremoved fruit were located where the fruit location index was greater than 2.5. This study indicated that the relative location of fruit in a limb with respect to the shaking location has critical influence on the fruit detachment efficiency. The study provided baseline information for improving the fruit canopy management and fruit removal techniques to potentially improve fruit removal percentage.