Patent ID: 6040916
Filing Date: 2000-03-21
Classification: B60G,B60T,G01B

Abstract:
A process for determining a condition of a road surface, comprising:beaming light onto the road surface, said light including a first light fraction having a first wavelength range which is not significantly absorbed by water/ice, and a second light fraction having a second wavelength range which is significantly absorbed by water/ice, said first light fraction including first light components with differing wavelengths;detecting backscattered light from the road surface;analyzing the backscattered light from the road surface to obtain a spectral intensity distribution curve;determining an approximation reference curve for spectral intensity distribution of the backscattered light when the road is dry using spectral data of the detected backscattered light;calculating a difference between spectral data of light backscattered from the second light fraction and corresponding data of the approximation reference curve for at least one wavelength of the second wavelength range, to obtain a difference curve; anddetermining the condition of the road surface based on the calculated difference curve; whereinthe second light fraction contains a plurality of different wavelengths; andthe difference between the spectral data of the second backscattered-light fraction and the corresponding approximation reference curve data is determined as a difference curve between a measured spectral curve of the backscattered light and the approximation reference curve in the second wavelength range.