Investigation of wireless magnetometer in sensing magnetic field changes at different car direction and speed

Chin Fhong Soon,Marlia Morsin,Chiok Chuan Lim,Siti Hajar Aminah Ali,Nafarizal Nayan,See Khee Ye,Kian Sek Tee,Munzilah Md Rohani

doi:10.11591/eei.v10i2.2707

Abstract

The embedment of induction loop underground for traffic volume monitoring caused damaging effects to the road and reduced road surface aesthetics. A wireless magnetometer implanted underground in a small uniform area was developed to detect three-axis magnetic flux changes due to the perturbation of vehicle passing over the sensor. In this project, a wireless magnetometer sensor system operating at a radio frequency of 2.4 GHz for detecting and transmitting Z-field data has been developed to investigate the patterns of magnetic field associated with the car directions and speed. This is the first report in revealing the responses of the sensor to different car speed and sensing directions. Field tests were conducted by car passes over in a direction in-line or countering the X and Y axes of the magnetometer. The results showed that the strong magnetic field density as low as -100 to -230 μT could be generated when a car passed over the sensor in a direction countering X and Y axes. The speed detection limit of the sensor is 60 kmph. The X, Y and Z flux patterns obtained is import in designing an algorithm for accurate detection and counting of vehicles.

Highlights

Underground electrical wire used as the induction-loop or piezoelectric traffic sensor is the present technique [1] commonly used to detect the presence of a vehicle, in which, the changes of magnetic field in the induction-loop sensors embedded underground are send via the electrical wire to an electrical meter and computer system
For the fundamental test of the magnetometer, it was found that the magnetometer is highly sensitive and generate inverting, non-inverting or biphasic magnetic field patterns in response to ferrous object passing over the sensor which is depending on the direction of the object and the coordinate system of the sensor Figure 7
A wireless magnetometer sensor node and gateway for recording the measured magnetic field strength and direction have been developed for vehicle detection

Summary

Introduction

Underground electrical wire used as the induction-loop or piezoelectric traffic sensor is the present technique [1] commonly used to detect the presence of a vehicle, in which, the changes of magnetic field in the induction-loop sensors embedded underground are send via the electrical wire to an electrical meter and computer system. This technology can be used for counting vehicles or traffic-actuated signal control.

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