Experimental study of a vehicle detector with an AMR sensor

This paper proposes a vehicle detector with an anisotropic magnetoresistive (AMR) sensor and addresses experimental study carried out to show the detector's characteristics and performance. The detector consists of an AMR sensor and mechanical and electronic apparatuses. Composed of four magnetoresistors, the AMR sensor senses disturbance of the earth's magnetic field caused by a moving vehicle over the sensor itself and then produces an output indicative of the moving vehicle. Experiments have been carried out with three stages. At the first stage, the outputs of the sensor have been analyzed to show the validity of the detector's circuit and the detecting method. At the second stage, the detector has been tested on a local highway in Korea. Through the field tests, the outputs of the detector in response to various kinds of moving vehicles have been collected and analyzed. At the final stage, to verify the performance of the detector, traffic volumes on the highway have been measured with the detector and compared with the exact traffic volumes in a highly congested traffic.