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THECOMMERCIAL GREENHOUSEGROWER • MAY 2018
• RO"OTS
Camera-basedplant sensing systems and robots for
harvesting, sorting andgradingdifferent greenhouse
cropswere themain topics of a tour of the greenhouse
researchdepartment of theDutchWageningenUniversity
&Research, writesStevenVale.
Organisedby the greenhousedivisionof the country’s
National Technical Association (NVTL), the informativeday
beganwith a tour of theAgroFoodRobotics labs at the
WageningenUniversity&Research (WUR) campus.
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researchdepartment was adarkened labwherework is
underway to seek an answer to thequestionof howmuch
earlier a camera candetect plant diseases than the
naked eye?
Theproject stems from an earlier one at the turnof the
century to remotely detect lycopene content in tomatoes.
Now, theywant to use similar hyperspectral camera
technology to seewhether aplant is sick or healthy,
and at the time of our visit the focuswas ondetecting
diseases onpotatoplants, but it shouldbepossible touse
the technology for greenhouse crops.
A standard cameraproduces colour images consisting
of red, green andbluepixels (visible spectrumbetween
400nm and800nm).WUR computer processes images
from two types of hyperspectral ‘new technology
cameras’ - one in the range 400-1000nm (visible light and
nearby infraredVIS-NIR), and the other in the range 900-
1700nm (shortwave infraredSWIR).
It is still early days, and they are still searching for the
best combinationof lights. Currently halogen types
are used, but theplan is to trial a number of LED
combinations in the future. Also, the cameras currently
useddo not gobelow 400nm, something they hope to
change in the future.
The next stopwas the agrorobotics andmechantronics
labwhere senior researcher and robot specialist Jochen
Hemming spoke about a number of projects. He joined
WUR in2000 and arrivedmidway through the cucumber
harvesting robot project.
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1998.When it ended in 2001, the robot coulddetect 94%
of fruits andharvest 74%of them, and someparts of
this robot technologywere used in subsequent projects,
includingonewith sweet peppers.
Around1.3billion sweet peppers aremanually harvested
inEurope each year, reason enough to try todevelop a
robotic harvester. Oneproject included theEuropean
CROPS (Clever robots for Crops), which ran from
2010-2014.
Automating the harvestingof sweet peppers is not easy,
saidMr Hemming. “There is notmuch space tooperate,
andwith a high temperature andRHmore than 70%, this
is a hostile environment for high-tech kit,” he said.
InCROPS, a robotic armwas developed in conjunction
with the Technical University ofMunich, inGermany.
The use of plasticpeppers allowed the experiments to
continue year-round. Several different grippers andplastic
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company calledFesto.
HELPINGHANDS
WUR researchers are using computer processed camera
images todetect plant diseaseproblems.
