TheEconomistFebruary 8th 2020 691S
lowly but surely, a spidery machine
about the size of a golf cart swings an
electrode over a tray of plants. Every few
seconds there is a small puff of smoke as a
weed keels over, having been zapped with a
high voltage. The device doing the zapping
is a prototype weeding robot developed by
the Small Robot Company, a new firm oper-
ating out of an old munitions depot near
Salisbury, in south-west Britain.
Such machines, called “agribots”, are
appearing in many shapes and sizes from a
variety of companies. Muddy tracks from
other prototypes lead into the Small Robot
Company’s workshop, where a row of 3d
printers make bright orange components
out of plastic. That makes parts easier to
find should they fall off in a field, which is a
sure sign that farmers are at work here,
with roboticists and scientists.
Weed control is essential for improving
crop yields, but it is getting increasingly
difficult. Some weeds are becoming resis-
tant to herbicides, which face stricter regu-
lation and in some cases are being banned.
On top of that, many consumers want or-ganic produce. And labour shortages mean
that repeatedly tilling the soil to disrupt
weed growth using a mechanical hoe
towed behind a tractor is costly, time con-
suming and not always practical.
Weeding is a chore that most farmers
would happily hand to robots. But for a ro-
bot to do the job properly it must be able to
distinguish a weed from what is being cul-
tivated. That is becoming easier with ad-
vances in computer vision. Artificial-intel-
ligence (ai) algorithms are getting better at
classifying images. Some phone apps can
now identify a plant from just a photo. Ro-
bots equipped with cameras will not only
weed but automate other farming roles.
Agribots, driverless tractors and other
types of farm automation form an industry
that is expected to grow at around 23% a
year and to be worth more than $20bn by2025, according to MarketsandMarkets, an
American research firm.
Having spotted a weed, there are several
ways to try to kill it. The Small Robot Com-
pany’s weeding agribot, called Dick, elec-
trocutes them. The robot’s wheels work
like an electrode to make contact with the
ground while another electrode is moved
to touch the plant. This makes a circuit
through the plant and creates heat, effec-
tively boiling the plant’s cells and killing it
from stem to root instantly. It can take sev-
eral thousand volts, although this is adjust-
ed according to the type of weed. The rem-
nants of the plant can then be left to
naturally decompose into the soil.Shocking
Dick will work with two other agribots,
Tom and Harry, all of them electrically
powered. The idea, says Ben Scott-Robin-
son, one of the company’s co-founders, is
that Tom will routinely scan fields to a level
of detail of just a few centimetres. Using its
cameras and other sensors, the spindly
four-wheel-drive machine can cover about
20 hectares a day, mapping the health of ev-
ery plant, along with soil conditions. When
weeds appear, Dick will be dispatched to
zap them. Harry, the third agribot, is under
development for tasks such as seeding and
applying precise levels of fertiliser to each
plant, a process known as microdosing.
Tom will go into commercial produc-
tion in August. Early versions are already in
use on some farms in Britain, including theAgricultureFarming with Tom, Dick and Harry
WEST DEAN
Using cameras and ai, agricultural robots are on the riseScience & technology
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