The technology, which was devised through the EU-sponsored project Friction, allows vehicles to ‘see’ the road ahead by combining information from several sensors.
Swedish company Optical Sensors’ Road Eye device uses lasers to illuminate a spot on the road just ahead of the vehicle with two wavelengths of infrared light. A light-sensitive diode then measures the amount of light reflected back at each wavelength.
The Friction team demonstrated that Road Eye was good at discriminating between dry asphalt and asphalt covered with snow, ice or water, but found telling the difference between ice and water more difficult.
The researchers also looked at a camera that detects polarised light reflected from the road about 25m ahead. They found that the camera could see further than the Road Eye, but as it relies on ambient illumination it does not work as well under low-light conditions. However, tests showed that it can detect a wet or icy road with up to 80 per cent accuracy.
The group also experimented with a radar system operating at 24GHZ. They found that by comparing the amount of energy reflected back from the road at two different polarisation angles, they could tell the difference between a dry, wet, icy or snowy surface up to 30m ahead.
The researchers integrated this information with hardware that is capable of making hundreds of traction estimates a second.
It is expected that Friction’s automotive partners, Fiat and Volvo, and other manufacturers, will introduce friction-sensing features to their safety packages in a couple of years.