Road condition detecting unit identifying state of road surface lying before moving motor vehicle - uses two adjustable light transmitting and receiving systems at different angles of elevation and supplying evaluation circuit correlating receiver signals

摘要

Light signals reflected from a road surface section (SB), illuminated by respectively assigned light transmitters, are detected and supplied to an evaluation unit (A). The two light transmitting and receiving systems (SE1, SE2) are so arranged at the vehicle, that the same road surface section (SB) is illuminated at different elevation angles and optically scanned. The evaluation unit (A) carries out a correlation of the signals detected from the two light receivers. The correlation peak values are compared with stored values derived empirically for various surface roughnesses. An appropriate reaction is activated if the comparison result indicates a condition of lower roughness, e.g. due to ice. ADVANTAGE - Alterations in road surface condition due, e.g. to rainfall or icing, can be detected.