|Authors: ||J. Hemming, B.A.J. van Tuijl, W. Gauchel, E. Wais|
|Keywords: ||greenhouse, adaptive jaws, Fin Ray effect, lip-type, grasping, gripper|
This paper focusses on field experiments with two different types of end-effectors for robotic harvesting of sweet-pepper fruits.
One of the major issues is to reach, grasp and detach the fruit efficiently, without damaging it, while avoiding obstacles in the environment.
End-effectors for harvesting fruit must be able to adapt to different fruit sizes and geometries.
Two types of end-effectors were designed and realized.
The first one had four fingers which utilized the “Fin Ray” effect to grip the fruit.
A scissor-like cut mechanism on top of the fingers was used to cut through the fruit peduncle.
The second, a lip-type end-effector first stabilized the fruit using a suction cup after which two rings enclosed and cut the peduncle with a circular blade integrated in the upper lip.
Both end-effectors had integrated miniature cameras with a LED illumination system: one Time of Flight camera and the other a colour camera.
To study the performance of the end-effectors a number of harvesting experiments were performed in commercial sweet-pepper greenhouses.
Special attention was paid to the following aspects: positioning at the target fruit, separation of the fruit from the plant, fruit damage, leaf damage and plant stem damage.
Both end-effector designs had their strengths and weaknesses.
The Fin ray type end-effector harvested a maximum of 80% of the fruits on the plant, the lip-type end-effector a maximum of 76% of the fruits.
In none of the experiments more than 64% of the fruit could be harvested without fruit damage.
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