In many fields, exact and fast information about the specific environmental conditions are required so as to initiate an appropriate response to the detected environmental conditions. For instance, an adequate assessment of the environmental conditions on road surfaces may significantly contribute to enhanced traffic safety, since corresponding decisions made by road administrators may be based on this information. In particular, any information on road sections having ice or moisture formed thereon may help to significantly improve traffic safety.
Thus, one of the key components of modern Road Weather Information Systems (RWIS) is the monitoring of the current road surface conditions, wherein the detection of water, snow, ice and the beginning formation of ice, is one of the most important pieces of information for traffic safety. For these reasons we developed a new sensor system to detect the presence of water or ice films on surfaces based on a patented technology researched by the Neuronica Laboratory.
The system is based on a multi-frequency capacitive measurement and the effect that water and ice have different dielectric constants. Accumulation of ice or water on the sensing surface of the sensor leads to a change of the effective capacitance value of the sensor. The change of the dielectric constant is measured using a sophisticated, high-sensitive, differential capacitance measurement circuit, able to classify the substance on the surface of the sensor in the complete interesting frequency domain, namely in the range of 50 Hz to several MHz.
This capacitive system is particularly interesting for road surface conditions monitoring, because it doesn’t need electrodes or others electrical parts to be exposed to the stress of i.e. cars. Its durability and accurate sensing, allowing the system to find applications in other fields such as ice detection on airplane wings or any type of surface where ice accretion has to be detected. Experimental results reveal that the system cannot only detect the presence of ice or water but also the exact point of ice formation, which is one of the most important information for road security.