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

Olive harvesting require a large amount of hand labour, mainly in sloped and traditional olive orchards that are difficult to be mechanize. Harvesting labour represents the main part of work; therefore, it should be the first target to improve olive growing mechanization. In the last 50 years, trunk shakers have become the most widespread method for olive harvesting, improving effective field capacity and reducing harvesting cost. However, to date, it is unclear how fruits are detached from bearing branches. To gather more information about fruit detachment principles, a high-speed commercial camera (240 frames per second) and bluish background were used to allow recognition of olive fruits. Video analysis was performed using free software (tracker, version 4.92), obtaining fruit movement parameters such as velocity, acceleration and stalk torsion. An orbital trunk shaker hitched to a low-power caterpillar tractor was employed to shake high-density olive trees (Olea europaea L. 'Frantoio') located in Perugia, Italy. Fruit harvesting was performed in the first week of November, while the Jaen fruit ripeness index was between 1 and 3. The results showed a complex pattern of movement during the shaking process, made up of linear movement of fruit, a pendulous and tilting movement of fruit to bearing branches, torsion of fruit to bearing branches, and a pendulous and tilting movement of the branch. Fruit torsion did not often exceed 90°, but it generated high bending and inertial forces that can have a significant impact on fruit detachment. Our results suggest that fruit movement patterns during tree shaking can play a role in fruit detachment by contributing to decreased fruit detachment force, which is currently only measured linearly.