Agriculture Reference
In-Depth Information
7.4.1 H
ORTICULTURAL
A
SPECTS
OF
R
OBOTIC
H
ARVESTING
Modifications and improvements of cultural practices for mechanization are con-
tinually being made through research and experience (Sims, 1969). To have a suc-
cessful automated/mechanized system, the cultural practices must be designed for
the machine and the variety (Davis, 1969). A systems development approach must
be followed to ensure that the cultural practices are suited for the crop variety and
machinery systems being considered (Sims, 1969). The major aspects related to cul-
tural practices that affect fruit and vegetable mechanical harvesting include field con-
ditions, plant population and spacing, and plant shape and size. Efficient harvesting
mechanization cannot be achieved by machine design alone. Establishing favorable
field conditions for the harvesting system under development has to be considered
before the harvesting system can be effectively developed (Wolf and Alper, 1983).
Peterson et al. (1999) developed a robotic bulk harvesting system for apples. They
trained the apple trees using a Y-trellis system and found them to be compatible with the
mechanical robotic harvesting. Fruit was trained to grow on the side and lower branches
to improve fruit detection and removal. They further suggested that pruning could
enhance the harvesting process by removing unproductive branches that block effec-
tive harvesting. Further research was suggested to determine the variety and rootstock
combinations most compatible with the training and harvesting system. The concept of
designing groves for optimal economic gain requires an optimal combination of varie-
ties, rootstocks, grove layout, production practices, and harvesting methodologies.
7.4.1.1 Plant Population and Spacing
Harvesting equipment can operate at maximum productivity when the workspace has
been organized to minimize inefficient obstacles, standardize fruit presentation, pro-
vide sufficient alleyways, and maximize fruit density on uniform growth planes.
Certain tree species and even certain varieties within species have an optimal sub-
sistence area for best fruit production, which provides a proper ratio between the num-
ber of leaves needed to produce carbohydrates and other organic compounds, and the
number of developing fruits (Monselise and Goldschmidt, 1982). The woody mass—
roots, trunk, scaffolds, and branches—support the tree canopy, but contribute mini-
mally toward fruit development once nutrient uptake and moisture demand are met.
However, they continue to use the tree's resources to maintain themselves, presenting
obstructions to robotic harvesting. Ben-Tal (1983) suggested that maximum yield per
unit area would be achieved by a large number of relatively small trees, indicating that
smaller robotic systems may actually provide a better economic return.
Scalability of robotic systems is an important economic factor that impacts the
design of the plant growth system. The productivity of large multiple arm systems
versus smaller more agile humanlike robots is an important economic question.
Large equipment systems require wide row spacing, whereas smaller systems can
work in a more confined grove configuration. Optimally, the fruit should be grown
in a hedge row configuration where the plants produce a maximum number of fruits
over the surface area (Ben-Tal, 1983). This suggests that trees or plants be grown at
a close spacing so that the growth plane is uniform with minimal scalloping of the
hedge between plants.
