Vibration transmission analysis in monumental olive trees for precision pruning: the PULP system approach

Olive growing traditional areas are characterized by monumental olive trees. Mechanical harvesting is also applied to these trees using branch shaking machines, but incorrect tree architecture reduces applied vibrations transmission. A new pruning model can improve mechanical harvesting efficiency by focusing on the study of vibration transmission in the tree. Therefore, the aim of this study was to evaluate the transmission of vibrations, to develop a model of precision pruning. The PULP system (pruning of unvibrating localized portions) records the transmission of vibrations through a series of accelerometers placed on branches of different orders. The experiment was carried out in a commercial olive orchard in Apulia. An evaluation in pruning and harvesting was carried out followed by the measurement of yield and harvesting efficiency. During pruning, the highest decrement in vibration transmission was from secondary (4.56×10-4 V) to tertiary branches (1.74×10-4 V). Similar values were observed during harvesting, but vibrations transmission inside seemed different. The detachment index showed no significant differences before and after harvesting, highlighting no influence of fruits position inside the canopy. The trees, on which was recorded a yield of 108±7.08 kg tree-1, in the first 12 s of shaking led to a harvesting efficiency of 80±3%. These preliminary data were necessary to better understand the vibration transmission and the different branches’ behaviour. Further studies are necessary in the coming years to improve and use this prototype to realize a precision pruning method for trees harvested with trunk shakers.