December 1, 2007
Measuring the amount of fruit detachment force and its distribution throughout the tree canopy under real harvesting conditions can assist in improving the existing harvesting machines. The goal of this study was to evaluate the detachment force exerted on individual oranges located in different tree canopy positions during harvesting by a tractor-driven, canopy-shaking harvesting machine. Multi-node, ZigBee-based wireless sensors equipped with tripleaxis accelerometer sensors were developed for this study. Sensors were placed at various locations in tree canopies in different groves. The maximum vibration and detachment forces for fruit detachment at different canopy positions were measured, and the force distribution pattern within the tree canopy was characterized. The force exerted on the fruit was dependent on the location of the fruit in the canopy. The average maximum detachment force for 'Hamlin' was 25.3 kg-f (force) and 23.9 kg-f for 'Valencia' oranges. In addition to maximum force, the duration of shaking is an important factor determining efficiency of fruit detachment.