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

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