Vibration analysis of the fruit detachment process in late-season 'Valencia' orange with canopy shaker technology

The mechanical harvesting of juice oranges can be achieved by the application of forced vibration to the tree canopy to detach fruit. Among the available harvesting technologies, canopy shaker systems have the advantage of working without stoppages between trees, with rods that penetrate the tree canopy generating low-frequency, high-amplitude movement. The objective of this work is to analyse the fruit detachment process to improve the design and management of canopy shaker systems, reducing the risk of damage to tree and fruit during the mechanical harvesting process. Three different canopy shaker systems were used to remove oranges in a well-adapted intensive orchard during the harvesting period. The fruit detachment process was recorded with a triaxial accelerometer sensor with a datalogger inserted into each tested fruit. Fruit movement displayed a similar frequency value as harvester rods (4.1-4.9 Hz), while the resultant acceleration depended on the interaction of the tree-machine system (38.8-60.4 m s−2). The fruit detachment event occurrence required a vibration time ranging between 1.45 and 5.75 s, which can limit the machine's maximum speed. After the detachment event, fruit presented a short mean time (0.28 s) with no contact with other fruit, branch or machine. The vibration of fruit during the harvesting process was greater, in terms of maximum acceleration, after the detachment event (527.6 m s−2) than before (401.0 m s−2). The use of a catch frame to collect fruit and of padding material in the machinery are fundamental measures to reduce the damage caused to fruit with canopy shaker technologies.