The Research And Implementation Of A RFID Localization System

RFID location systems have special research significance in locating and tracking areas due to their high security,low cost and flexibility features.They also have high practical values in military and commercial fields.The proposed indoor position system was researched based on the real time human tracking and monitoring application.The hardware,localization algorithm and software were implemented to meet the particular project requirements.The performance of the hardware and algorithm is concluded in the end.The main work can be summarized as follows:(1)The proposed wearable RFID location device with the function of position banding was developed.The anti-dropped method was implemented by using the heart rate measuring method and anti-picked watchband with circuit inside.To overcome the power sensitivity problem,the ultra low power components were selected,the current consumption was analyzed and calculated,and the redundant units were avoided.The power supply of the LCD was determined by human arm posture which achieved by the three-axis accelerometer.The wearable feature was met by selecting small size components,minimizing PCB and using 3D printing technology.The communication protocol and software drivers were accomplished.(2)The virtual referenced tag based fingerprint localization algorithm and software were researched and implemented.The algorithm adopted the idea of pattern matching,and can be described as two steps.In off-line stage,the RSSI(Received Signal Strength Indicator)data of the RFID location tag in a series of fixed points,these points are averagely selected according to the given granularity,are recorded to form a RSSI fingerprint database,the RSSI in a position called the fingerprint.In on-line stage,the RSSI data of the location tag are received,and matched with the fingerprint database,the position is calculated by weighted average method.The experimental result showed that the maximum communication range between the wearable location card and the location base station was 250m;the location card’s battery life was about 62h which was 44%longer than the same device without using the low power method,and 244%longer than an heart rate smart watch;The device can achieve ±3BPS heart rate measuring precision and 100%dropping detection accuracy;The location error of the system was lower than 3.5m by 70%.The accuracy and stability were increased by 38%and 51%compared with the range-based localization algorithm;The average system delay was 3s.The system has achieved the design indexes.