Vehicle Monitoring System Based On AMR Sensor

With the rapid development of economic, and a sharp increase in road vehicles, traffic problems have become increasingly serious. In this context, Intelligent Transportation System (ITS) is evolved, which is based on modern technology and information. The vehicle detection technology is both the foundation of ITS and decision-making basis, and is an important part of ITS. Road usage, traffic flow, speed, vehicle classification, vehicle distance, the forward direction, vehicle weight and other basic traffic flow parameters all can be obtained through the vehicle detection.Most vehicles are ferromagnetic structures, which can be seen as bipolar magnets in the local magnetic field, the disturbance of the geomagnetic field is different as the vehicle speed and direction of movement is different. Vehicle detection system based on magnetic field sensor is to detect vehicle by measuring the disturbance of the geomagnetic field and with information processing, vehicle recognition, vehicle detection technology. AMR sensor has the characteristic of anisotropic magnetoresistive effect, high precision, low power consumption, easy integration, which is design for working in geomagnetism and calculating vehicle speed, distinguishing vehicle classification.This paper presents a vehicle detection system based on AMR sensor HMC1043. The main Work is as follows:(1) A vehicle detection system is present based on AMR sensor, by analyzing the current vehicle detection methods. The basic structure and characteristics of the AMR sensor is also be introduced.(2) The hardware circuit of the system is designed, which is including the hardware of magnetic field measurement modules and data acquisition processing center. The hardware includes signal conditioning circuit, A/D circuit, CPU peripheral circuit, memory circuit, power circuit, communication circuit, t clock circuit, etc.(3) A vehicle model fuzzy recognition algorithm is proposed based on magnetic disturbance curve. The algorithm is simple and effective and fit for AMR system.(4) The embedded software is designed, by using IAR integrated development environment. According to the basic functions of the detection systems, we realize the design of each application module, and give part of the program flow chart.The vehicle detection system is initially completed, which based on AMR sensor. As a practical system, there are many areas need to improve, they need further work to study and improve.