| 摘要 |
PROBLEM TO BE SOLVED: To accurately discriminate the condition of a road surface independently of different vehicle types. SOLUTION: A sound sensor is used for detecting the sounds of a vehicle travelling on a road. Fourier transform is applied to the intensity of the sounds. The intensity of each frequency component of the sounds of each vehicle passing within a preset time is converted into total intensity to calculate the intensity of all band frequencies. Based on a vehicle extraction threshold value, the sounds of each vehicle is extracted. Standardizing processing is given to the frequency property of the extracted sounds of each travelling vehicle with a high-pass filter frequency to calculate the intensity of standardized frequencies for all vehicles. In accordance with the intensity of the standardized frequencies of all vehicles with the standardizing processing, a first threshold value is set between the wet condition and the dry condition of the road surface, and a second threshold value is set between the dry condition and the snow pressed condition of the road surface. When the intensity of the standardized frequency is the first threshold value or greater, the wet condition of the road surface is determined. When it is between the first threshold value and the second threshold value, the dry condition of the road surface is determined. When it is smaller than the second threshold value, the snow pressed condition of the road surface is determined. COPYRIGHT: (C)2008,JPO&INPIT |
