Night
vision devices attached to vehicles there by reduces the chances of accidents
both on and off the roads. Many leading car manufacturers have diverted their
full R&D towards developing accident prevention technologies rather than
going for higher efficiencies or higher torque production.
Electromagnetic
Spectrum
Before
going into the night vision systems it is necessary to understand something
about the electromagnetic spectrum. Humans are visible only to the rays felling
under the visible region of electromagnetic spectrum and are invisible to both
the infra-red as well as the ultra violet region of the electromagnetic
spectrum.
But
night vision technology makes it possible for the humans to view the rays
felling in the infra-red region of the electromagnetic spectrum, that is
generally the night vision systems used in automobiles captures the infra-red
image of distant obstacles on road as every object emits infra-red rays (heat
rays) even during night. This image is viewed in a screen and the driver can
thus apply the brakes as required.
Two Types Of Night Vision Technologies On The Market
Far
Infrared (FIR) and Near Infrared (NIR) .FIR detects the radiation which all
objects emit, while NIR detects the reflected illumination in a frequency just
outside the visible range of a human being. All cars today have an acceptable
"night vision" system. That is the high beam headlights of the
vehicle. Even though they could be improved theirperformances are at least
acceptable. However, in many areas, highbeams are of very limited use due to
oncoming traffic. The insufficient night-time visibility originates in the fact
that the high beam headlights are rarely possible to use. A Night Vision system
must therefore be a system that increases visibility in situations where only
low beam headlights can be used today.
Fir And Nir Night Vision Systems
Both
NIR and FIR technology offer substantial benefits in different conditions. Both
types of systems can also be used together with high beam headlights. The
benefit of NIR systems together with high beams may be limited, as NIR systems
could be compared with driving using high beams, but without blinding the other
road users. The longer range of FIR systems would also make them very effective
on dark roads as complements to the high beams of the vehicle. However, as
concluded the previous section. Pedestrian detection while facing other
vehicles with oncoming headlights should be the main evaluation criteria of a
Night Vision system.
The Human-Machine Interface
The
population group likely to benefit the most of all from the extra information
provided is elderly people due to the degradation in vision this group
experience with age (see table 1). However, it has also been shown that this
group is less likely to accept, or utilize, the extra information. The
Human-Machine Interface (HMI) between the system and the driver is fundamental
for successful acceptance, especially among elderly drivers. Proper
understanding of the required performance of the system and the expectation of
the driver is a prerequisite for designing a good HMI. The primary issue should
not be the type of display, but what information to provide to the driver and
how it should be done.
A Night Vision System May Operate In Following Modes
Use
the system as a look-ahead display to increase the preview — an extended view
into the road ahead.
1)
Use the system as a look-ahead display combined with a warning that directs the
driver's attention to thedisplay when a risk has been identified.
2)
Use the system as a look-ahead display but highlighting risky objects like
pedestrians.
3)
Use the sensor as a data source only and provide a warning when a risk exceeds
a given threshold.
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