Drivers
can struggle to see when driving at night in a rainstorm or snowstorm, but a smart
headlight system invented by researchers at Carnegie Mellon
University’s Robotics
Institute can improve visibility by constantly redirecting light to shine between
particles of precipitation.

The
system, demonstrated in laboratory tests, prevents the distracting and
sometimes dangerous glare that occurs when headlight beams are reflected by
precipitation back toward the driver.

“If you’re
driving in a thunderstorm, the smart headlights will make it seem like it’s a
drizzle,” said Srinivasa Narasimhan, associate professor of robotics.

The system
uses a camera to track the motion of raindrops and snowflakes and then applies
a computer algorithm to predict where those particles will be just a few
milliseconds later. The light projection system then adjusts to deactivate
light beams that would otherwise illuminate the particles in their predicted
positions.

“A human
eye will not be able to see that flicker of the headlights,” Narasimhan said. “And because the precipitation particles aren’t being illuminated, the driver
won’t see the rain or snow either.”

To people,
rain can appear as elongated streaks that seem to fill the air. To high-speed
cameras, however, rain consists of sparsely spaced, discrete drops. That leaves
plenty of space between the drops where light can be effectively distributed if
the system can respond rapidly, Narasimhan said.

In their
laboratory tests, Narasimhan and his research team demonstrated that their
system could detect raindrops, predict their movement, and adjust a light
projector accordingly in 13 msec. At low speeds, such a system could eliminate
70% to 80% of visible rain during a heavy storm, while losing only 5% or 6% of
the light from the headlamp.

To operate
at highway speeds and to work effectively in snow and hail, the system’s
response will need to be reduced to just a few milliseconds, Narasimhan said.
The laboratory tests have demonstrated the feasibility of the system, however,
and the researchers are confident that the speed of the system can be boosted.

The test
apparatus, for instance, couples a camera with an off-the-shelf DLP projector.
Road-worthy systems likely would be based on arrays of light-emitting diode
(LED) light sources in which individual elements could be turned on or off,
depending on the location of raindrops. New LED technology could make it
possible to combine LED light sources with image sensors on a single chip,
enabling high-speed operation at low cost.

Narasimhan’s
team is now engineering a more compact version of the smart headlight that in
coming years could be installed in a car for road testing.

Though a
smart headlight system will never be able to eliminate all precipitation from
the driver’s field of view, simply reducing the amount of reflection and
distortion caused by precipitation can substantially improve visibility and
reduce driver distraction. Another benefit is that the system also can detect
oncoming cars and direct the headlight beams away from the eyes of those
drivers, eliminating the need to shift from high to low beams.

“One good
thing is that the system will not fail in a catastrophic way,” Narasimhan said. “If it fails, it is just a normal headlight.”

Source: Carnegie Mellon University