Geomagnetic Vehicle Detection Technology Based On Wireless Sensor Networks

Vehicle detection technology is the main research content of intelligent traffic system, and is an important basis for the optimization of traffic signal control and vehicle traffic flow guidance system. Recently, traffic jam and traffic pollution have become serious problems we are facing, which urgently requires intelligent traffic signal control technology to improve the road capacity. Accurate and real-time traffic flow data would provide basic data for the adaptive signal control. There are many drawbacks in vehicle detection’technology at present, for instance that the loop vehicle detector has difficulty in installing, and there is also a problem of video detector in accuracy influenced on the environment.The project proposed a design method for the geomagnetic vehicle detection system based on wireless sensor network to satisfy the requirements of current vehicle detection, under the background of Internet of Vehicles. Moreover, this paper has designed the wireless geomagnetic vehicle detector, which support detects32vehicle detection nodes synchronously. The paper mainly includes the following three parts:Firstly, this paper have analyzed and processed the signals from geomagnetic sensor, and designed the algorithm of Adaptive thresholds for state machines based on the tri-axis magnetic signal fusion to detect the state of vehicle accurately. The system filtered out the interference in identification caused by the error data with the algorithm of signal-processed and signal variance classification. The detector improved the accuracy of detection node in a complex multivariate environment through real-time updating the original signal, and designed the high-accuracy vehicle detector with the function of self-tuning and self-adaptive.Secondly, the system optimized the communication in Wireless Sensor Networks. Taking into account the vehicle detection system has the characteristics of long distance communication, frequent wireless transmission, and large capacity of network, we designed the wireless sensor network in band of433MHz based on time division multiple access (TDMA) mode. The network completed the management of the detection node accessing and information transmission, to ensure the reliability of transmission of multi-nodes synchronously. The wireless communication protocol and time synchronization algorithm which uses automatic adjustment function based on the offset can also be applied, it can maximize the reduction of th e detection-node energy-costing under the condition of stable wireless communication.Thirdly, according to the transport protocol and time synchronization mechanism with self-adjusting offset method in ensuring the quality of wireless communication, maximize lower energy costs.The system completed the wireless magnetic vehicle detector systems platform, which includes vehicle detection nodes, wireless sensor network gateway, hardware and software of data conversion unit, wireless protocol, design for network architecture and issuance management software of the detection information. It reduced power consumption of detection nodes adopting dynamic power optimization strategies, and provided a method based on multiple detection nodes interconnected sensing characteristics and traffic flow models to calculate the queue length using Multi-sensor fusion algorithm.At the end of the work, the author tested and evaluated the wireless magnetic vehicle detector in the actual environment. The result shows that the wireless magnetic vehicle detector would detect the vehicles with the characteristics of real-time, accurate and efficient. On the other hand, the detection accuracy and communication range of the detector was able to satisfy the needs of the detection system with the feature of low power, self-correcting, adaptive, small volume, high precision, avoiding broken roads. It has high value to research and application.