  Robot-assisted fruit harvesting has been a critical research direction
supporting sustainable crop production. One important determinant of system
behavior and efficiency is the end-effector that comes in direct contact with
the crop during harvesting and directly affects harvesting success. Harvesting
avocados poses unique challenges not addressed by existing end-effectors
(namely, they have uneven surfaces and irregular shapes grow on thick
peduncles, and have a sturdy calyx attached). The work reported in this paper
contributes a new end-effector design suitable for avocado picking. A rigid
system design with a two-stage rotational motion is developed, to first grasp
the avocado and then detach it from its peduncle. A force analysis is conducted
to determine key design parameters. Preliminary experiments demonstrate the
efficiency of the developed end-effector to pick and apply a moment to an
avocado from a specific viewpoint (as compared to pulling it directly), and
in-lab experiments show that the end-effector can grasp and retrieve avocados
with a 100% success rate.
