An Experimental Study and Mathematical Modeling of Vibration Transfer in Pistachio Trees Using an Inertia-Type Trunk Shaker and Field-Adapted Wireless Sensors

Ma, Ruijun; Homayouni, Taymaz; Toudeshki, Arash; Ehsani, Reza; Zhang, Xiaohua

doi:10.1155/2022/9966848

Cited by 5 publications

(4 citation statements)

References 24 publications

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“…We observe the highest degree of transmissibility in the case of citrus, which coincides with results reported by Castro-Garcia et al (2020). 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).…”

Section: Discussionsupporting

confidence: 92%

Configurable trunk shaker for the mechanical harvesting of different fruit branches

Sola-Guirado

Sanchez-Cachinero

Tombesi

2023

Journal of Vibration and Control

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Trunk shakers perform a forced vibration that should be set according to tree species and architecture to efficiently detach fruits. However, manufacturing companies produce designs that are poorly customisable according to different trees. This work presents a prototype that is configurable in amplitude and frequency of vibration, which has been developed to generate the different vibration patterns required by various fruit trees. To study the feasibility of the developed technology, we built a test bench with a post, to which we fixed olive, almond and orange tree branches, and tested different configurations of the machine (frequencies from 12.25 to 20.75 Hz and eccentricities from 58 to 86 mm). Acceleration values were recorded at different points: the trunk shaker, the post in the grip, the top of the post, and in each branch. We recorded a large loss of acceleration transmissibility between the shaker and the post (20%–60%) due to existing frictions that dissipate energy through heat loss. There is a non-linear increase between vibration frequency and the resultant acceleration value recorded, as well as with increasing eccentricity. The shaker was able to provide a different vibration pattern in each configuration, affecting the transmission of vibration in each of the branches studied, for which mean acceleration transmissibility ranged between 82% (almond), 104% (olive) and 136% (orange).

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Section: Discussionsupporting

confidence: 92%

Configurable trunk shaker for the mechanical harvesting of different fruit branches

Sola-Guirado

Sanchez-Cachinero

Tombesi

2023

Journal of Vibration and Control

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“…The kinetic energy transferred by the shaker to the main branch of significantly large trees is essentially dissipated because of the complex transmission vibration mechanism among the branches, the leaf drags, and the internal energy losses within the wood and root/soil system (Leone et al, 2015;Ma et al, 2022). Notably, the aerodynamic drag forces of the foliage in the air (hydraulic damping), the interaction of the side branches attached to the main limb (mass damping), and the damping effects within the stem and root system (viscoelastic damping) strongly attenuate the vibration produced by the shaker (Upadhyaya et al, 1981;D'Agostino et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2023

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IntroductionThe Mediterranean basin is home to centuries-old large olive trees; high-vigor cultivars are widespread, with training forms poorly adapted to mechanical harvesting by trunk/branch shakers. The significant quantity of leaves, the considerable tree height, and the presence of multiple dichotomous hanging branches reduce the transmission of vibrations applied by the branch-shaker machines. Thus, re-shaping pruning may improve the performance of this modern mechanical harvesting method by focusing on removing both the hanging branches and those forming dichotomies. The goal of this study was to evaluate the dynamic responses of large-sized olive trees to pruning (or not) through various field tests under different excitation forces. We hypothesized that more rational pruning could significantly increase vibration transmissions.MethodsTo assess the transmission of vibrations, tests were conducted before and after the pruning on representative trees. Tri-axial accelerometers packed in a small titanium housing were used. Trees were assessed before and after the re-shaping pruning. This study reports the first data about the dynamic behavior of centuries-old tree skeletons, in the context of very large-sized olive trees, while taking into account the effects of two different vibrations application modes: a realistic one represented by the system vibration head-tree, originated when the gripper of a shaking machine wrapped and fastened the main branch of the olive trees, and a more speculative one, represented by a single impulse of a short-duration force originated by a hammer.ResultsAfter pruning, spectral density increased 10 fold in the tertiary branches of pruned trees (ranging 1.0–10 m s−2) compared to that of not-pruned ones (ranging 0.1–1.0 m s−2) at frequency >50 Hz under vibration excitation. Moreover, vibrational decay times (120–150 ms) and amplitude (>10−1 m s−2) were higher under single-impulse excitation.DiscussionA more rational pruning applied to ancient large-sized olive trees significantly increased the vibration transmission under both impulse and vibratory excitation forces, without affected their typical “look”. Moreover, these insights are helpful in turn in achieving maximum fruit-removal efficiency. These insights could be applied to various horticultural conditions which would improve the economic sustainability of monumental olive trees, a key portion of the Mediterranean landscape and cultural heritage.

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“…Maximum fruit removal with a shaker is achieved when the shaking frequencies approach the tree's natural frequency. However, the proper shaking frequency varies for each individual tree, as the tree's natural frequency is a function of its size, age, morphology, wood properties, moisture content, and leaf density [11,12]. The tree's natural frequency can even shift during the harvest season due to mass changes during harvesting [13].…”

Section: Introductionmentioning

confidence: 99%

“…Olive trees significantly damp trunk vibrational energy due to their wood properties and branch orientation (Figure 2). the tree's natural frequency is a function of its size, age, morphology, wood properties moisture content, and leaf density [11,12]. The tree's natural frequency can even shift dur ing the harvest season due to mass changes during harvesting [13].…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Trunk and Canopy Shaking Improves Table Olive Harvester Efficiency versus Trunk Shaking Alone

et al. 2023

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Production of California table olives has declined significantly in recent years due to hand harvesting costs, often over 60% of gross return. Mechanical harvesting could sharply decrease harvest costs, increasing economic viability. Mechanical harvester efficiency is a combination of the percentage of the total fruit on a tree removed by a harvester, and the time required to do so. A comparison between an experimental canopy contact shaker and a commercial trunk shaker demonstrated low harvest efficiencies and no significant differences in harvester efficiency between the two, averaging no more than 8%. However, simultaneously combining both shaking methods increased fruit removal to an economically feasible 75% and produced better fruit quality. Combining both shaking methods increased the price per ton by 63% versus trunk shaking and 35% versus canopy shaking. These results suggest a mechanical olive harvester that simultaneously combines trunk and canopy shaking is more efficient than either shaking method alone, and, has potential for economically feasible mechanical table olive harvesting.

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An Experimental Study and Mathematical Modeling of Vibration Transfer in Pistachio Trees Using an Inertia-Type Trunk Shaker and Field-Adapted Wireless Sensors

Cited by 5 publications

References 24 publications

Configurable trunk shaker for the mechanical harvesting of different fruit branches

Configurable trunk shaker for the mechanical harvesting of different fruit branches

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

Simultaneous Trunk and Canopy Shaking Improves Table Olive Harvester Efficiency versus Trunk Shaking Alone

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