Researchers in the US have come up with a solution to the problem of headlight glare reducing driver visibility in the rain. It is a problem with which anyone driving on UK roads in the last three months will be more than familiar. Scientists at Carnegie Mellon University have developed a smart headlight that can shine "around" rain.

The idea is that the headlight will be able to predict where rain falls and adjust light beams accordingly.

Prototype success

Using low-cost, off-the-shelf components the researchers set about developing a system that switches off rays of light that hit raindrops. The smart headlight consists of a projector, camera and beam-splitter.

The camera takes images of the raindrops, a processor uses a predictive algorithm to work out where rain will fall, and then the projector switches off light rays that would have normally hit the raindrops.

The process from capture to reaction takes about 13 milliseconds. The result is a slightly dimmer headlight, but one that blocks out glare from falling rain and snow. An early prototype, tested in the lab in conjunction with artificial rain, found that the system worked better at slower speeds.

The researchers simulated different car speeds and rainfall intensity and found that in severe thunderstorm rain, the system had a 79% success rate in making raindrops invisible when the car travelled at 30km/h, while at 100km/h that fell to around 20%.

Carnegie Mellon's computer science professor Srinivasa Narasimhan, part of the team working on the project, admitted that the system had some way to go before it could be used in real cars.