Research On RFID-Based In/Out Detection Method

Automatic detection of the identity and moving direction of people passing-through a door has practically importance for many application scenarios in daily life.For example,it can help track the distribution of workers in multiple rooms,then determine better task allocation.However,the existing solutions usually have to work with many special constraints,which are difficult to be satisfied in the factories.For example,the solution based on computer vision requires that the sight between the camera and the face should not be blocked by objects,while the biometric technology needs limited features like very clean fingerprints to play a good role in in and out detection.In this paper,we use RFID technology to propose a kind of barrier-free personnel passing detection system called RF-Monitor,which can accurately detect the identity situation of people entering and leaving the entrance.Specifically,we deploy an RFID antenna on one side of the entrance and two reference tags on the other side of the entrance.At the same time,each person has an RFID tag on his/her hat/helmet.When the RFID tag wearer passes through the entrance,the reader antenna continuously receives the signals from the reference tags and the human body tag.The human body will block the direct path between RFID reader and the reference tags when he/she passes through.The signal propagation path changes and will cause the change of the received reference tag signal.By filtering the RFID signal waveforms caused by relevant personnel and reference tags,and then analyzing and summarizing the processed waveforms,the RF-Monitor system can accurately tell us the identity of corresponding personnel and its moving direction(in or out).The experimental results show that the detection accuracy of the RF-Monitoring system can reach more than 90% under various conditions,achieving reliable environmental adaptability and practicability.