Research And Design Of Height–detection System For Vehicles On Expressway

With the trend of developing extrude traffic in modern city, there are more and more means of transportation such as trestle,viaduct,passenger foot-bridge,tunnel,system of street lamp lighting and so on.In one hand,these establishments enhance the capacity of the transportation and remit the pressure of the traffic jams,but in the other hand,they make the composition of road neet verge to complex and bring abut some latent hidden troubles of traffic safety,and then impact the city's lifeline such as cable root,communication line,way's current,lighting facalities and so on,and so far as to emperil the life security of the mass. With the rapid development of traffic in modern city,traffic accident happens frequently, especially the accident like wedging or hitting bridges caused by some high vehicles .Though most traffic administrative departmens adopt measures such as increasing constraction hight permitted sign,this kind of traffic accident still happens occasionally.In order to reduce such accidents, a new design of height–detection system for vehicles is introduced in this paper. The design has the follow feathers: the convenience for installation, cheap, strong ability of interference-resistant. It can also accurately reflect the height of vehicles. This text introduces the background of the research,the current developing situation of height–detection system for vehicles,and states reseachful contents,sense and applying value.The system is mainly consisted by singlechip, photoelectric switch, and coupler, multivibrator and so on. In this paper, the design of hardware and software are expounded in detail. Hardware design mainly includes singlechip minimum system design, launching and receiving circuit design, signal processing circuit design and laser-alignment circuit design. This text mainly introduces the smallest components and the structure of parts of MC9S12DG128, principle and structure of landing and receiving circuit, and signal processing circuits are mainly expounds the principle of light modulation and demodulation.Software design includes launching module and the receiving module. Launch module introduces methods to control produce and emission of cycle time delay signal by process.It also describes the pulse width measurement methods and height measurement. The interference- resistance measures are presented and the causes of error are analyzed. Through the visual system conducted experiments, this paper proved that the vehicle high detection system design was successful, and analyses the causes of the system error and the maximum error of measurement. Experiments show that this design can judge whether the vehicle is more than limit ,and can measure the hight,withthe measurement accuracy for specific height of±5cm. Finally,the paper summarizes the research achievements, and made a further state of the existing problems and places needs improve.The innovations are as follows:1,To measure the vehicle's actual height, a screen composed by launching sensor array and receiving sensor array is used to complete the measurement and the center distance between adjacent sensors is 5cm. The method improves the measurement accuracy and low the cost.2,Phase method is proposed to overcome interference between the photoelectric switches, which not only reduces the error of measurement, but also improves the accuracy of the system.3,Designs the light modulation circuit and the demodulation circuit, solves the problem caused by interference of light and improves measurement accuracy of. System.4,with a view of real-time and precision of the system, 16-bit microcontroller is used for analysing and processing data, improving data processing speed and completing dynamic measurement.5,According to the design complished the production of real, through the experiment obtained accurate data, this paper verifies designed of the vehicle height detection system.6,Analyses the causes of the system error and the maximum error of measurement.