Tracking olive fruit movement and twisting using video analysis during harvesting process

Olive harvesting requires a high hand labour mainly in traditional olive orchards difficult to be mechanized. It was due to, currently, is not possible to detach all fruits from the tree only by using mechanical harvesting, but it requires aid from operators with long poles or hand held devices to reach high harvesting efficiency rates. Therefore, detachment process should be the first target to improve harvest efficiency. Currently, fruit retention force (FRF) is used as the main parameter to describe how difficult is to detach fruits from the tree, and it only measures traction force. However, until now it is unclear how FRF, acceleration or tree architecture are involved in fruit detaching process. In order to give more information about mechanic behavior of olive stalk, trial was carried out during ripening process in two main olive (Olea europaea L.) cultivars: Frantoio and Arbequina. FRF under traction force was measured applying different stalk spinning angles (0, 90, 180, 270, 360, 540, 720º) before traction. FRF was considered to be 0 when fruit was detached from the bearing branch during the spinning process. Results showed that FRF was significantly reduced when stalk turning was applied before to pull out the fruit. FRF reduction increases when stalk spinning was higher. Differences were kept along fruit ripeness process. Significant differences (P<0.05) were commonly found over 180 º of stalk turning, and when ripeness process was advanced, fruits were detached only by applying an stalk spinning over 540 º. In addition different behavior between olive cultivars was described, which can be related to stalk length. In conclusion, trunk shaker should be improved to generate stalk spinning during detachment process in order to get higher harvesting efficiencies without need of aid by other harvesting methods such as long poles or hand held canopy shakers.