Nissan's Automatic Headlight System Tells Evening From Shadows

Aug 11, 2008
Naoshige Shimizu, Nikkei Electronics
The Smart Auto Headlight automatically turns on headlights at twilight.
The Smart Auto Headlight automatically turns on headlights at twilight.
[Click to enlarge image]
Accidents most frequently occur in the time zone ending approximately one hour before the sunset.
Accidents most frequently occur in the time zone ending approximately one hour before the sunset.
[Click to enlarge image]
Illumination sensor on the right side of the dashboard
Illumination sensor on the right side of the dashboard
[Click to enlarge image]

Nissan Motor Co Ltd developed a new automatic headlight system that turns on about 30-40 minutes earlier than the existing automatic headlights at twilight and does not turn on in the shadows of a tree or a building.

In order to turn on the headlights earlier than the existing systems at twilight, the company increased the sensitivity of the illumination sensors by dozens of times and revised the control logic that determines the surrounding environment.

Aiming to reduce the number of car accidents, Nissan plans to commercialize the new headlight system within 2008. The automatic headlights equipped in existing Nissan models will be replaced by the new system, the Smart Auto Headlight, the company said.

According to Nissan's data about the fatality and serious injury rates by time of day, accidents most frequently occur in the time zone ending approximately one hour before the sunset. The new system is designed to reduce the accident rate during this accident-prone time zone by automatically turning on the lights to warn other vehicles.

The system determines the surrounding environment based on the values obtained by the illumination sensors. Those values are constantly changing. In addition to the improvement of illumination sensor performance, the threshold and other values used by the decision logic circuit can be set in details this time, enabling the system to recognize the shadows of a tree or a building.

For example, when the value decreases sharply, the system determines that the vehicle is going into a tunnel. When the value decreases gradually, the system determines that it is before the sunset.

Moreover, the new system has a function to turn on headlights in concert with the operation of the wipers.