A road surface condition sensing system for Advanced Cruise-Assist Highway System (AHS) has been researched since 1996. Although road surface conditions are indicated with qualitative expressions such as dry, wet, snow-covered or frozen, for vehicle control application, it is necessary to provide information by converting to quantitative values such as road surface friction coefficient. Thus, it is necessary to detect or recognise the degree of dryness or wetness of the road surface. Fuzzy inference is an effective method for quantifying the state that is indicated by the degree of the road surface condition. Therefore, a road surface condition sensing system that employs fuzzy inference in the basic algorithm was developed. Laser radar was used as the sensor head that is able to measure the distance from round trip travelling time of pulsed laser beam and the intensity of the reflected light simultaneously. The system and the inference algorithm are outlined. In addition, the effectiveness of this sensing system for collecting road maintenance information was investigated.
Abstract