Simulation Study of Citrus Tree Canopy Motion During Harvesting Using a Canopy Shaker

Current canopy shaker harvesting machines were designed and optimized based on experimental studies about their fruit removal efficiency. To further improve the performance of canopy shaker harvesting machines, a better understanding of the interaction between the shaker and the tree is needed. Simulation studies for an entire tree or fruit-stem subsystems are available for trunk shaker mechanical harvesters, but no such study has been reported using a canopy shaker. The goal of this study was to develop and evaluate a simulation framework for predicting the interaction between the tree and the canopy shaker using finite element methods. A field experiment was conducted on three Late Navel citrus trees using a tractor-drawn canopy shaker at 180 and 230 cycles per minute (cpm) frequencies. The acceleration data from this experiment were used for simulation validation. In this study, the trees were modeled using SolidWorks and simulated using ANSYS. The input force was estimated using the acceleration of points on the tines of the canopy shaker. The mechanical properties of the citrus tree wood were determined under the assumption that it is isotropic in nature. The three citrus trees were modeled, and the acceleration data from the simulation were compared against the experimental data. Adjusted R2 values of 0.6 at the lower frequency (180 cpm) and 0.54 at the higher frequency (230 cpm) were observed between the two datasets. It was also observed that for both the experimental and the ANSYS simulation data, the equivalent stress and resultant acceleration were greater for the higher frequency than for the lower frequency.