Road surface discriminator and apparatus applying same
US5652655A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 1995 |
| Grant date | Jul 29, 1997 |
| Priority date | — |
| Expiry date | Dec 19, 2015 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB60T2210/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Light is projected upon a road surface (LD) from a light source (11) for illuminating the road surface. Diffuse reflected light from the road surface (LD) is received by light sensors (31A, 31B) through a spatial filter, and the resulting light-reception signals are applied to a differential amplifier circuit (51). A center-frequency component corresponding to the spatial frequency of the spatial filter is extracted by a tracking band-pass filter (52), and the intensity (Da) thereof is detected by an amplitude detector circuit (54). Low-frequency component intensity (Db) corresponding to a spatial frequency lower than the spatial frequency of the spatial filter is detected by a tracking low-pass filter (55) and an amplitude detector circuit (56). The condition of the road surface is judged to be snow, gravel or asphalt in a discriminating circuit (60) based upon the center-frequency component intensity (Da) and the low-frequency component intensity (Db).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.