The Research And Applications Of Vehicle Detection Algorithms Based On Wireless Sensor Network

In recent years,with the rapid growth of car ownership,the traffic congestion problem is becoming increasingly serious in the center of the city.So there is an urgent demand for construction of the real-time traffic monitoring and parking management system.Wireless sensor network(WSN)has the characteristics of low cost,low power,and miniaturization.So it is gradually used in the traffic information collection system.Magnetic sensor uses the geomagnetic disturbance detection principle to realize vehicle detection.Deployment the sensor nodes on the road,and the roadside parking spaces,the WSN system can realize the traffic information collection.Currently,the traffic detection technology based on WSN is not mature.The vehicle detection accuracy is not high.Based on the existing research results,the thesis proposes a traffic information acquisition system,which includes parking space occupancy,vehicle count,and vehicle speed information detection.Research in this thesis will significantly improve the accuracy of traffic information detection.The main contributions of this thesis are as follows:1)It proposes a parking vehicle detection algorithm.Firstly,we propose the feature extraction method based on analysis of the magnetic signal.Then an algorithm based on the threshold and state machine was designed for parking vehicle detection.Using the threshold detection mechanism is to reduce the computational requirement of the algorithm so that it can be implemented on the sensor node's processor and generate detection results in real time.2)By using the arithmetic mean method,a dynamic vehicle detection algorithm is proposed.The algorithm can be used for dynamic vehicle detection and speed estimation.Time synchronization is the key factor affecting the accuracy of speed calculation.This chapter presents a low-cost,high-precision time synchronization mechanism.Router is responsible for the time synchronization and the vehicle speed estimation.Experiment verifies the accuracy of the vehicle speed detection algorithm.3)This work has constructed an experimental platform.The wireless sensor network is composed of sensor nodes,router nodes,and base station.We developed a server system using Java language and MySQL database.Using the graphical client interface,user can check the parking space status,the average traffic flow and vehicle speed.4)By running the experiment system for several months in the city road.We observe that the accuracy rate of the parking vehicle detection algorithm is better than 98%.The dynamic vehicle detection accuracy rate is more than 97%,and the accuracy rate to estimate speed of the vehicle is more than 90%.