April 2020 / www.theengineer.co.uk
automot PRODUCT i v e FEATURE
t echnology
44
Night time is statistically the
most dangerous period on the
road. A study in the US found
that an alarming 75 per cent of
pedestrian fatalities occurred
after dark, while collisions
with large animals such as
deer also go up substantially at night.
In an effort to reduce these risks,
automotive manufacturers started
experimenting with night vision
systems back in the early 2000s. Since
then the technology has increased in
sophistication. And with the growing
importance of ADAS functions and move
towards self-driving cars, it’s no longer
just drivers that need to see in the dark.
Infrared sensing is the obvious
solution; it’s vastly cheaper than LiDAR,
more accurate than radar and better
in poor visibility than a conventional
camera. Historically, the only real debate
has been between active sensors, which
use a dedicated emitter to bounce
short-wave infrared off the target, and
passive systems, which detect long-wave
‘thermal infrared’ without the need for
illumination.
“Active systems are generally
cheaper, but the main advantage of
using a passive sensor is that it relies
completely on infrared emitted by
other objects,” comments Chris Posch,
director of engineering for automotive
applications at FLIR Systems. “If every
car on the road had an active night vision
system they’d all be blinding each other.”
FLIR supplies sensors to Swedish
firm Veoneer, which works with the
likes of Audi, Volkswagen and Porsche.
In recent years, these passive infrared
systems appear to have cornered the
market when it comes to driver-focused
night vision and they are also popular
with those working on self-driving cars.
The situation is a little different
when you look at ADAS systems, which
have to be affordable enough for even
the smallest city car. Here, radar is
generally used at present – sometimes
fused with visible light to improve
accuracy. Posch, however, predicts
that falling costs and more demanding
performance requirements will push
companies towards infrared: “There’s
been a lot of recent press on how poorly
some automatic emergency braking
(AEB) systems perform. The regulatory
bodies are likely to start making their
qualification tests a little harder, which
will nudge people towards more effective
systems.”
A recent test of four different AEB
systems by the American Automobile
Night riders
Automotive night vision systems can help drivers –
and cars – to see clearly when they need it most
Chris pickering reports
The night
vision system
on the Bentley
Continental GT
acquires data
using a thermal
camera mounted
on the front of the
grille
if every car on the road had
active night vision they’d all be
blinding each other
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