Assessment of aerial and underground vibration transmission in mechanically trunk shaken olive trees

Abstract

The present study analyses the transmission of vibrations generated from a multidirectional trunk shaker to olive tree structure considering both the aerial zone (trunk and branches) and the underground zone (the coarse root). The vibration characterization was conducted by measuring acceleration on several points of the tree during harvesting operations. The influence of two different heights of shaker head clamping was analysed. In addition, a dynamic probing was performed in order to evaluate soil compaction. The results showed that the vibration performed by the trunk shaker head, corresponding to an acceleration resultant of approximately 77 ms–2 with a dominant vibration frequency of 18 Hz, increased up to 106% in branches and decreased up to 90% in trunks. At root level, where the analysis was carried out at 1/3 and 2/3 of the coarse root length, the acceleration values diminished significantly to 17 ms–2 and 12 ms–2, respectively. Soil dynamic resistance was lower (36 kg cm–2) near the trees than between the trees (53 kg cm–2). The vibration transmission to the aerial and the underground parts diversely influences the dynamic behaviour of the olive tree, considering an operational frequency of a commercial trunk shaker. The assessment of vibration transmission to the aerial part could contribute to improve fruit detachment and reduce branch breaking and leaf detachment. While vibration transmission to the underground part rises new challenges considering soil compaction in olive groves.

Configurable trunk shaker for the mechanical harvesting of different fruit branches

“…The lowest transmissibility values were obtained in the case of almond trees, which is in line with what has been studied in the case of pistachio (Ma et al, 2022), another similar nut. In the case of olive branches, the amplification factor is close to 100%, matching with the behaviour they exhibit in the field (Sola-Guirado et al, 2018). It should be noted that the actual joints of branches with trees are considerably more complex than those shown in this work due to the variability of the biomechanical properties of the whole assembly (Théckès et al, 2015).…”

“…The acceleration values obtained by several researchers at the trunk point (Torregrosa et al, 2010; Leone et al, 2015) are higher than the ones measured at the post in the grip, but they are not comparable as, in our case, an artificial metal pole is used as a kind of tool to anchor the different species of tree branches. What is important for the purpose of this work are the values recorded in the branches, and in this part, the values recorded in the resultant accelerations of the branches do show a great degree of similarity with other works: 40–120 m s −2 at 15–20 Hz in pistachio trees (Homayouni et al, 2022); 121–430 m s −2 at 15 Hz in oranges (Torregrosa et al, 2010); and 80–100 m s −2 at 17 Hz in olives (Sola-Guirado et al, 2018). In all these cases, acceleration transmissibility has values similar to those shown in Figure 8.…”

Fruiting, Morphology, and Architecture of ‘Arbequina’ and ‘Calatina’ Olive Branches

“…The main problem in this type of planting system is the marked alternate bearing, favored by the age and size of the plant and the decay of the wood, the lack of irrigation, and severe pruning every 3-5 years [17,18]. Mechanical or mechanized harvesting is difficult due to the size of the trees [19][20][21], the location of the orchard (areas unfavorable to reach), and the layout of the land (high slopes) [22]. Therefore, because of low profitability, most of these traditional, extensive olive orchards were abandoned in the last years, causing dangerous losses of genetic resources and a reduction in chemical and sensory diversification of the oils available in the market [23].…”

Re-shaping pruning improves the dynamic response of centuries-old olive trees to branch-shaker vibrations application

“…The harvest is executed by collecting the olives from the ground every 2 weeks for 4-5 months, for the production of lamp oil (Famiani et al, 2014). The use of shaking machines to mechanize olive harvesting from the crown is particularly significant owing to the exceedingly positive effects in oilquality improvement (Clodoveo et al, 2014;Sola-Guirado et al, 2018). When the olive tree size is too large, it is better to apply the vibrations to the easily accessible primary branches (Tombesi, 1990).…”