| In the present, the expressway of china is in rapid development. At the same time,the bad road surface condition such as wet、icy or snowy condition is causing moreand more traffic accidents, as the friction coefficient of road surface declines underbad weather. However, the main way of detecting road surface condition in china isstill artificial patrol, which is neither convenient nor real-time. The cost of abroadequipment which can distinguish the road surface condition is so high that it could notbe used extensively while there is still not mature product in the domestic. This paperis based on the sub project which is “study of road surface condition for highwayweather monitor”.This paper develops a non-contact road surface condition sensor based ondouble-wavelength detection and solves a few key technical problems which candistinguish the following road surface condition: dry、wet、icy and snowy condition.At the same time, six equipments had been installed on G50expressway road inChongqing and they have already been tested for a year. In order to fulfil the task, thefollowing thing has been done:1. The principle exploration of road surface condition detection. Take advantageof geometry optics to build the theory model of road surface and explain therelationship between scattered light power and road surface weather condition. Byusing double wavelength, the road surface condition can be effectively detected.2. Modulation of laser and PID temperature control. The laser is modulated toisolate the DC light signal from sunlight, at the same time, the detector works in aconstant-temperature environment to make the system stable.3. Amplification of weak signal and lock-in method. The weak light signal needto be amplified in a low-noise, big magnification way. The effective signal is obtainedby lock-in method.After the outdoor test for a year, the non-contact road surface condition system isin normal situation and the accurate rate comes to the design request. |
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