Copyright 2013 Optical Sensors
Road Eye    Updated in August 2014
A laser sensor concept for monitoring road state.
The Road eye is a patented (pat number SE 531949C2) contact less sensor concept for monitoring the road surface. The information from the sensor can for instance be used for warning a driver for low friction when there is ice on the road. The measuring principle is spectral analysis of  backscattered laser radiation from the road surface  using two lasers at  IR wavelengths where the radiation is absorbed by ice and water. One laser at a little shorter wavelength is used for reference. The sensors are not yet in serial production. We are preparing for volume production of two models.
 At LTU in Luleå, Sweden a lot of basic research has been done by Johan Casselgren et al on the optical properties of road surfaces covered with water, ice and snow. Johan C has also worked with algorithms for converting raw data to road state and also friction between tires and road. Johan's doctorial thesis is found via the following link http://pure.ltu.se/portal/files/32995443/Johan_Casselgren.pdf
The LTU group has been awarded with "Stora Trafiksäkerhetspriset 2012".
The sensor is made in two versions:  - one to be mounted on vehicles, Road eye Short Distance (SD) - and one Road Long Distance LD,  to be mounted at roadside.
The SD and LD sensors are able to identify some important road conditions like.
- Dry road (this is the most important one to identify since it is associated with the best friction - as soon as the road surface is not dry the road friction is reduced)
- Moisture on road
- Wet road
- Clear ice - i e ice without air bubbles, a very dangerous road condition
- Ice/Packed snow.

More information about the sensors is available at http://www.opticalsensors.se/slippery.html.
About the Short Distance model SD.
The range of the SD sensor is up to about 2 meters and the update time is about 60 ms which can be converted to a distance shorter than the length of a car for all possible speeds on public roads.
The Road eye SD sensor has been used in a lot of projects at LTU. LTU has for instance been strongly involved in the Intelligent road project. In that project it has for instance been demonstrated to map data from vehicles in real time on a web page. The SD type has been investigated in big road research projects like the IVSS projects www.ivss.se   The final report from the subproject Road Friction Estimate 2 is available at     www.ivss.se/upload/ivss_refll_slutrapport.pdf

The SD model has been tested by car manufacturers and suppliers and it has - as mentioned - been used in several research project.            
About the Long Distance model LD:
The LD model is designed to be mounted beside the road for monitoring the road state. The range is up to about 10 meters. It is demonstrated to integrate it with a camera so that the data will be available together with a real time picture. It is also demonstrated to make the information from the sensor and the camera available on the internet via a GPRS modem.