Effect of fruit location on apple detachment with mechanical shaking

Fresh market apples are picked manually around the world. To reduce dependence on seasonal labour and minimise harvest costs, shake and catch harvesting methods have been investigated (no commercialised product). During shaking, certain amount of fruits could not be detached primarily due to insufficient level of transferred energy. The primary goal of this study was to investigate the efficiency in detaching fruit from different locations of tree branches in modern trellis-trained trees. A fruit location index was formulated and estimated to identify the location of targeted apples on a branch by considering the geometric dimensions of fruit bearing twig (twig index) and excited branch (branch index). A dynamic test system was developed to measure the response of fruit under certain shaking modes. The weights of twig index and branch index were optimised with maximizing R2 of regression model between fruit acceleration and fruit location index. This study indicated that the fruit location has a critical influence on fruit detachment with shaking. Test fruits ('Envy' variety) could generally be detached within 5 s of shaking when fruit acceleration was higher than 5 g, and the corresponding fruit location indices were 0.071, 0.06, and 0.061 in three test frequencies. Harvesting tests showed that over 90% of fruits with location index greater than 0.06 were detached under 20 Hz shaking. Fruit quality assessment was not included in this study. The study provided baseline knowledge and information for improving the fruit canopy management practices to obtain high fruit removal efficiency.