Smart Headlights Improve Visibility in Rain

Carnegie Mellon researchers develop smart headlights that shine between raindrops to improve visibility at night.

The system employs a high-speed camera to predict within milliseconds where raindrops will fall and then deactivates light beams that otherwise would bounce off the precipitation and impair visibility.

“If you're driving in a thunderstorm, the smart headlights will make it seem like it's a drizzle,” says Srinivasa Narasimhan, associate professor of robotics. “A human eye will not be able to see that flicker of the headlights. And because the precipitation particles aren't being illuminated, the driver won't see the rain or snow either.”

He says the researchers analyzed rain with high-speed cameras and determined precipitation is made up of discrete drops with lots of space between them. They then created a smart system that effectively distributes light between the raindrops.

Conducting tests with a weather chamber in their lab, the researchers were able to adjust headlight illumination in a mere 13 milliseconds. That's good enough to effectively eliminate between 70%-80% of visible rain in a heavy storm with only a 5% or 6% loss of light.

Narasimhan says the team will need to cut the system's response time to just a couple of milliseconds to be effective in snow and hail at highway speeds and is confident of the feasibility of accomplishing that.

The Carnegie Mellon apparatus uses a camera with an off-the-shelf DLP projector. A university spokesman says the researchers believe they will have a prototype system capable of being mounted in a vehicle for testing in three years.

The smart headlight system never will eliminate all precipitation from the driver's field of view, the researchers admit. But they claim it can reduce reflection and distortion and minimize distraction.

A bonus benefit is that the system can detect oncoming cars and direct the headlight beams away from the eyes of those drivers. That would eliminate the need to switch from high to low beams. “One good thing is that the (smart headlight) system will not fail in a catastrophic way,” Narasimhan says. “If it fails, it is just a normal headlight.”

Carnegie Mellon says the Office of Naval Research, National Science Foundation, Samsung Advanced Institute of Technology and Intel helped fund the research.