Design And Implementation Of The Magnetoresistive Sensor-based Traffic Monitoring System

With the rapid development of economic and the improvement of people’s living standards, the number of cars has also continued to increase. This leads to large traffic pressure on urban roads and is prone to traffic accidents resulting in huge economic losses. Therefore, Intelligent Transportation System comes into being. Traffic information collection is the most critical aspect in intelligent transportation system, whether real-time traffic information and accurate collection is sent to the server or not is the key to intelligent transportation system.In this thesis, the traffic monitoring system is based on magnetoresistive sensor. Thesis analyzes several domestic and foreign common traffic monitoring technology, and utters the advantages and disadvantages. Secondly, the system involves an analysis of related technologies. It introduces the principle and the principle of the vehicle detecting of the magnetoresistive sensor, the wireless transmission communication of monitoring system, and the relevant knowledge of wireless sensor networks. Finally, and it designs and implements algorithms, software and hardware of the system.This system mainly uses the HMC5883 L triangle magnetoresistive sensor to detect the magnetic field of the earth, when the vehicle passes the sensor, the magnetic field near the sensor will change, this change is determined by detecting whether a vehicle passes or not. This paper proposes a detection algorithm based on state machine dynamic baseline adaptive threshold, the algorithm can accurately detect the presence or absence of the vehicle. Using two sensors, it can detect the speed of the vehicle. While the monitoring nodes receive traffic data, it will be sent via GPRS and stored on the server. Thesis designed a software while users can access the traffic information on the server from query software in order to gain relevant traffic information data.The system is tested, and the results show the algorithm monitor road traffic accurately due to high precision, correct hardware circuit design and simple and beautiful interface of the software.