Dynamic Speed Limit LED Sign System Based On Real-time Detection Of Ice And Snow Road Surface

Taking Xinjiang as a typical representative,the northwest cold region of China has a long winter time,a large amount of snowfall,long mileage and large proportion of low-grade highways,and the snow is not cleared in time,so the road surface is prone to snow,ice and other adverse driving phenomena.When encountering such icy and snowy roads,it is difficult for drivers to independently control safe speeds,which often results in various traffic accidents,and traffic managers often find it difficult to enforce the law.Therefore,it is particularly important to detect the ice and snow conditions on different roads in real time,and to provide drivers and traffic managers with safe speed limit authority values under the current road conditions in the form of dynamic speed limit signs.At present,the research of domestic and foreign scholars on the detection and recognition methods of ice and snow road conditions mostly focuses on ground sensing contact and multi-weather fusion,and this type of detection method requires high detection circuit integration accuracy and large investment.It is not universally applicable to low-grade highways in the wide area of western China.In addition,the existing highway speed limit in our country is still mainly based on static retro-reflective signs.If the driver still drives at this speed limit in an icy and snowy road environment,it is very easy to produce "speeding" in the technical sense.Therefore,to explore a dot matrix LED dynamic speed limit sign technology which can provide safety warning for drivers in real time is the key to achieve the goal of safe speed control for drivers.Aiming at the characteristics of low-grade highway ice and snow road surface,according to the principle of ultrasonic detection and recognition,this paper proposes a dot matrix LED dynamic speed limit sign system based on ultrasonic road ice and snow state detection.The system uses ultrasonic transceiver module to detect the road ice and snow state in real time.The detection information data is applied to the digital analog formula of the safe vehicle Velocity,and the value of Velocity is calculated,and then displayed to the dot matrix LED dynamic speed limit sign to warn the driver of the safe driving speed under the road condition.The main contents of this paper are as follows:(1)Extract three typical ice and snow road conditions common in low-grade highways: new snow,compacted snowboard,and ice board,and combine the three elements of people,vehicles and roads to analyze the three state roads Carry out safe driving speed modeling and judge three kinds of safe driving speeds on icy and snowy roads immediately;compares and analyzes existing ice and snow pavement detection and identification methods,and proposes ultrasonic Wave detection and identification method,and its application feasibility and related physical parameters are analyzed;(2)Based on the principle of ultrasonic detection and recognition,the ultrasonic echo reflection model is established,and the reflected echo waveforms and characteristic parameters of the three ice and snow road conditions collected through field experiments are differentially extracted.Then,the echo amplitude and voltage of three typical ice snow pavement states are analyzed and determined as follows: ice plate voltage > snow plate voltage > snow snow voltage;(3)According to the speed limit values of the three icy and snowy road conditions,the principle of ultrasonic detection and recognition,and system installation and application requirements,the system hardware circuit,software program and system peripheral component structure are designed,and the hardware circuit of the detection system is simulated and analyzed by the software Multisim,and the expected effect of each part of the detection system function design is achieved;(4)Based on the design of static speed limit sign,the structure of LED dynamic speed limit sign panel is designed.The uniformity of illuminance distribution of LED dot matrix light source on sign panel is verified and simulated by experimental test and optical simulation software trace / Pro.Finally,the "8" LED lattice,which is often used in dynamic speed limit signs,is taken as an example to simulate the software.It is verified that the illumination distribution of LED dot matrix speed limit sign meets the requirement that the non-uniformity of LED dot matrix speed limit sign is less than 10%,and the design technology of dot matrix LED dynamic speed limit sign is summarized.