Design, Construction, and Evaluation of a Three-Dimensional Vibratory Harvester for Tree Fruit

Abstract

HighlightsThree-dimensional excitation response of tree can be generated by orthogonal eccentric blocks.The three-dimensional vibratory harvester prototype was built, and the vibration response and harvesting test were carried out.Three-dimensional excitation applied to single main branch of the tree can result in high vibration on the whole tree. Abstract. To solve the problems associated with the mechanical harvesting of fruit, improve the harvesting efficiency, and reduce the damage to trees in the process of harvesting, a three-dimensional shaking mechanism with orthogonal eccentric blocks was designed. Three-dimensional excitation is generated to ensure that the fruit trees are subjected to noncircular excitation forces in different directions and further improve the fruit harvesting percentage. Firstly, the overall structure of the three-dimensional shaking mechanism with orthogonal eccentric blocks was designed, and the steady state response of the vibration system was obtained by establishing the dynamics model of the shaking mechanism-tree system. According to the vibration amplitude of the fruit tree under the action of three-dimensional shaking mechanism, the mass moment of the eccentric blocks, which are the key parts of the harvester, was determined to be 0.56 kg·m, and the size of the eccentric blocks was calculated. The hydraulic motors and cylinders that drive the shaking mechanism of the harvester were specified. Then a vibratory harvester prototype was assembled, and a vibration response test was carried out. The results showed that different branches of the test tree could obtain large acceleration magnitudes with low dispersion degree, which verified the effectiveness of the three-dimensional vibratory harvester. Finally, a harvesting test was conducted on a grapefruit tree. When the speed of the hydraulic motor to drive the shaking mechanism was 470 rev·min-1 and the shaking time was 10 s, the harvesting percentage reached 76.5%. Keywords: Acceleration response, Fruit harvester, Hydraulic system, Orthogonal eccentric blocks, Three-dimensional shaking mechanism.