Research On Detection Method Of Road Meteorological State Based On Multi-wavelength Laser Measurement

Detecting state aims to obtain highway road surface meteorological whether against traffic safety,such as water,freeze,etc,Accurate identification of these conditions,as well as accurate measurements of surface water and icing thickness,can ensure that the traffic department efficient scheduling traffic,highway department maintains the roads accurately,and drivers know the traffic conditions in real time.It is an important link of realizing highway intelligence and unimpeded travel.To meet the development needs of smart roads,based on the existing pavement meteorological state detection technology,this paper around laser measurement technology,from optical path characteristics to detection principle,and from structural design to performance analysis,a non-contact road weather detection sensor based on multiple shortwave infrared laser co-detection is systematically developed.Firstly,according to Lambert’s law,The formula model for measuring the thickness of pavement water was deduced,a thickness measurement method based on the dual wavelength co-detection is proposed.In addition,the propagation characteristics of Gaussian beam in lens system are studied,which provides a theoretical basis for the design of sensor detection optical path.The detection technology of weak signal is summarized,and the working principle of digital phase-locked amplifier is studied,which provides technical support for the development of upper computer.Then,the optical path structure is designed according to the propagation characteristics of Gaussian beam.We using the simulation software Trace Pro,to simulate and optimize the optical path,the light gathering efficiency of the backward scattering light can reach more than 90% no matter what Angle the system is used to detect.At the same time,we using Lab VIEW to developed the upper computer system,and combined with the light path structure,a physical platform has been built.Then,through infrared spectrum analysis,we have selected three wavelengths for use in the probe: 1064 nm,1310nm and 1550 nm,among them,1310 nm and 1550 nm are used to distinguish the meteorological state of road surface and measure the thickness of road surface ice;1064nm and 1310 nm are used for measuring the thickness of pavement water.We carried out simulation experiments on different road meteorological conditions on the experimental platform,by introducing the state parameter S,an effective state identification method is proposed,when the road is dry: S = 1;when there is water on the road: S ≤ 0.1425;when the road is icy: S > 0.1425 and S≠1.Finally,according to the simulation experiment,the parameter Q used to measure the thickness of pavement water was studied and calibrated,and multiple detection angles of different thickness of water were analyzed.When the sensor was measuring the thickness of pavement water,the accuracy reached the relevant national technical standards,and the effective detection Angle was 5°-20°;the detection range is greater than 3m;the water measuring range is greater than 8mm;the measurement accuracy of water thickness is±0.2mm.In addition,the method of measuring the thickness of road icing is also explored.When the degree of frost on the ice surface is weak,the thickness of the measured ice cover is greater than 3mm.