The Institute - September 2018 - 5
E N J OY I N G T H AT
C H A R D O N N AY ?
THANK A ROBOT
Machines to help California
grape growers conserve water
B Y K AT H Y P R E T Z
I NTN E R S I N CALI FO R N IA'S
Central and Napa valleys are facing
two shortages: of water and of workers.
What's more, the state's recent drought
has caused a financial strain for growers thanks to the cost of irrigating their thousands of
hectares of vines. And stepped-up enforcement of
immigration laws, competition from less strenuous
higher-paying jobs, and an aging workforce have led to
a labor shortage, according to Wine Spectator magazine.
When researchers from the University of California met with grape growers to discuss how technology could help them, the growers asked if their
irrigation systems could be made more efficient and
with less human intervention.
"I'm a roboticist, so whenever there's a problem, I
study whether a robot could solve it," says IEEE Senior
Member Stefano Carpin, a professor of electrical engineering and computer science at UC Merced.
Carpin leads a team of researchers from UC
Berkeley, UC Davis, and UC Merced who are building the Robot-Assisted Precision Irrigation Delivery
(RAPID) system [left]. The system involves inexpensive, adjustable, plastic water emitters attached to
the holes in drip irrigation lines. Each emitter would
help regulate the amount of water discharged. And
because there aren't enough workers to adjust the
hundreds of emitters each vineyard is expected to
need, the group is designing rugged, battery-operated
robots to move around and handle the job.
The project, launched in 2016 and funded by a
nearly US $1 million grant from the U.S. Department
of Agriculture, is part of the National Science
Foundation-led National Robotics Initiative.
"This robotic system would make fine-grain
adjustments to deliver water on a per-plant level,"
Carpin says. "We would reduce water use while
preserving the quality of the grapes."
RAPID: THOMAS THAYER; PRETZ: RANDI KLETT
GROW I N G BASICS
Growing grapes is a tricky business. Their quality
depends in part on how much water is absorbed by the
vines' roots. Current drip-irrigation systems consist of
a rubber pipe pierced with holes laid down along a row
of vines. Ideally, vineyards should apply localized stress
irrigation, which customizes the amount of water delivered to each vine. But most drip-irrigation systems
can't deliver water with precision. The drip pipes
have emitters spaced from 300 millimeters to 900 mm
apart-which can't be adjusted.
Water dripping through the holes wets the fields
in uniform blocks, often of around 64 hectares.
"There's a lot of variability in these blocks in terms of
soil moisture, microclimate, and weather conditions,
so delivering the same amount of water in a fixed flow
to the whole block is not optimal," Carpin says. "Some
grapes end up with too much, some with too little."
With RAPID, each watering pipe is, in effect,
turned into a precision irrigation system.
The team is exploring a plastic emitter with a cap
that can be turned by a robot to adjust the water flow.
Each emitter would cost about 20 cents.
"It's a simple system," Carpin says. "Turn the cap
clockwise to increase the flow and counterclockwise to
decrease it." He says he can't estimate how much water
the system might save until it has been tested.
To help determine when an adjustment is needed,
RAPID will rely on data from field-monitoring systems
such as drone and satellite imagery, weather satellites,
and services including the California Irrigation
Management Information System. CIMIS is a network
of more than 145 automated weather stations to help
irrigators manage their water.
Carpin is trying out the four-wheel Husky ground
vehicle from Clearpath Robotics-basically an
open-topped box that carries the elements of the
robot. He expects his finished vehicle will be slightly
larger than the Husky to accommodate batteries
and an arm with a grasping hand. The robot also will
have a GPS receiver to map its route and an RFID
reader on board to direct the machine to the emitter,
he says. The robot will position itself and with its
grasping hand turn the cap to adjust water flow, he
says, guided by readings from a monitoring system
plugged into its flash drive.
By next year, Carpin says, he will have a prototype of his system, and an irrigation pipe pierced
with holes will be retrofitted with the adjustable
emitters. He expects the system to be tested on a
farm, which has already been selected, by the summer of 2020.
Carpin estimates that initially each system will
cost in the tens of thousands of dollars, depending on
the size of the farm.
You can read about an earlier version of RAPID in
"DATE: A Handheld Co-Robotic Device for Automated
Tuning of Emitters to Enable Precision Irrigation,"
available in the IEEE Xplore Digital Library. ◆
The Robot-Assisted Precision Irrigation Delivery (RAPID) system is designed to turn the caps of drip irrigation lines to
adjust water flow. The robot collects data from field monitoring systems, such as weather satellites and drones, to help
determine how much water is needed on the fields.
S EP TEM B ER 2018 TH E IN STITUTE
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