Design and evaluation of a two-section canopy shaker with variable frequency for mechanical harvesting of citrus

Canopy shaking is one of the most commonly used techniques for mechanical harvesting of citrus fruits in orange juice industry.However,tree damage and low harvesting efficiency are the top concerns of growers in adopting the existing harvesting equipment on a large scale.The purpose of this research was to develop a novel canopy shaking system to minimize tree damage and maximize fruit removal for mechanical citrus harvesting.In this study,a two-section canopy shaker composing of top and bottom shaking systems mounted on two rotating drums was proposed and developed.It was configured with two sets of flexible bow-shaped shaking rods in a staggered distribution,which can shake the top and bottom zones of the tree canopy independently.The shaking system was designed based on a linked crank-rocker mechanism.Kinematic simulation analysis was conducted to verify the quick return characteristics and differential properties of this mechanism.Vibration test showed that the frequency of the shaking rod could be adjusted within a range of 1.1-8.8 Hz related to hydraulic motor speeds.The field tests of the shaking system with an average frequency of 4.7 Hz achieved a fruit removal percentage of 82.6%and tree damage rate of 5.4%under a tractor speed of 3 km/h.By contrast,the combined shaking frequency of 4.7 Hz&4.1 Hz of the canopy shaker produced less tree damage with a percentage of 3.9%.This study indicated that the two-section canopy shaker with an optimized frequency combination could be adaptable to the different zones of the tree canopy,and obtain lower tree damage and higher fruit removal percentage.

Selection and experimental evaluation of shaking rods of canopy shaker to reduce tree damage for citrus mechanical harvesting

Canopy shaking system is one of the research hotspots for large-scale mechanized fruits harvesting.Shaking rods considered as one of the essential components of canopy shaker are responsible for transferring mechanical energy from shaking mechanism to different regions of tree canopy.This transfer depends on the characteristics of the shaking rods that directly strike the tree canopy.In order to evaluate the effects of the shaking rods on tree damage level and fruit removal percentage,three kinds of shaking rods with different materials or shapes were selected.Based on the results of bending deformation tests,it was proven that the rigid shaking rod(R_(1))with the material of Polyvinyl Chloride(PVC)did more resistance against producing bending deformation in comparison with the other two types of shaking rods with the material of Polyamide Nylon 12(PA).By contrast,the position close to the free end of the flexible shaking rod was easier to be deformed by less external force.In addition,dynamic analysis and vibration performance tests indicated that the rigid shaking rod could produce stronger vibration with higher shaking frequency of 4.8 Hz and maximum acceleration of 31.4 m/s^(2).Finally,the results of field trials indicated that the flexible bow-shaped shaking rod(R_(3))has a better widespread performance to achieve comparative higher fruit removal percentage up to 82.6%while producing lower tree damage rate of 5.36%.This study demonstrates that the materials or shapes of the shaking rod could significantly influence the fruit detachment rate and tree damage level.This study would provide an essential reference for the application of shaking rods for canopy shaker.

Performance evaluation of lateral canopy shakers with catch frame for continuous harvesting of oranges for juice industry

Citrus is mainly oriented to fresh consumption,and harvesting is usually performed manually.However,the high cost of harvesting and the low availability of labour can compromise the profitability of the crop when it is destined to juice industry.The development of citrus mechanical harvesting for industrial processing is conditioned to reach a high fruit removal efficiency,with a reduced damage to both fruit and trees.The current machines available are very large,requiring extensive plantations with long rows of trees to be efficient.In this study,two lateral canopy shakers equipped with a catch frame were evaluated to harvest independently both sides of the hedge on intensive citrus plantations with the main objective of determining their performance and feasibility.The lateral canopy shakers tested were three tractor-drawn machines,one commercial machine and two prototypes.The tested machines reached a mean value of 78%of fruit removal.Besides,the prototypes,equipped with a catch frame,were able to recover a mean value of 70%of yield.Although the results were promising,for achieving an efficient result,the application of this harvesting technology still requires a process of improvement,and the adaptation of both the machine and the plantation.The machines should reduce the amount of post-harvest ground fruit(5.9%-10.4%).Tree damages generated by the contact of the catch frame with the trunk and the metal rods with main branches were the most relevant.Therefore,it is still necessary to increase the ground speed of the machinery and improving the design of the rods,regulating the rod penetrating deep in the canopy to improve the fruit recovery and limit the damage caused to the trees.