A Study on Intercepting Falling Fruits with Canopy Penetrating Rods

Abstract. Commercial tree shakers cause excessive fruit damage, largely due to fruit collisions with tree limbs during fruit drop. Machine prototypes featuring a multilevel fruit catching system with rods were developed in the 1970s to reduce such damage. The rods penetrated the canopy, and fruits either trickled through or rolled down the rods. Although the developed prototypes were promising, further optimization on their design was not pursued, partly due to decline in funding for mechanization research.

Optimizing the percentage of fruits intercepted by canopy-penetrating multi-rod catchers requires varying design parameters such as number, dimensions and positioning of rods. A simulation was developed to study the percentage of fruits landing on the rods before hitting a branch as the number of rod layers and their optimal vertical placements varied. The simulation utilized 3D computer models of trees and fruit positions, which were created via digitization.

Tree and fruit models were available for high density pear and cling peach trees. Without any rods, 36% of pears and 21% of peaches hit a branch as they fell through the canopy. For pears, the number of impacted fruit could be reduced to 22% with one layer of rods, down to 12% for four layers. For peaches, collisions could be reduced to 13% with one layer of rods, down to 8% for four layers. The number of non-impacted fruits decreases asymptotically as more rod layers are added, i.e., there is a diminishing return as more rod layers are added; hence, trade-offs would need to be considered.