To be able to enhance and test vehicle applications like for example anti-lock braking system (ABS) and traction control system (TCS) there is an interest in characterizing winter road conditions in terms of surface material and structure. In this project an optical method is used to make these characterizations.
Different phases of water (ice, snow and their mixes) have different resonance frequencies and it has previously been shown that these differences are greatest at near infrared wavelengths (1-2 µm). Hence, a sensor with three different laser wavelengths in this span has been developed and tested on real winter roads. The results show that it is possible to distinguish between different road conditions like snow, ice and water on an asphalt road, see figure 1. Further, to determine the surface roughness a model of light reflection from soils is applied on the reflections in different directions from the surface. This results in a measure of the roughness, which together with the surface material is the most important parameter to correctly determine road friction.
The project has previously been a part of the IVSS-program (Intelligent Vehicle Safety System) but is now a project within CASTT (Centre for Automotive Systems Technologies and Testing).