Research On3D Real Time Positioning System Based On RFID Sensor Networks

The rapid development of CPS (Cyber Physical Systems) and loT (internet of things) has greatly promoted the development of location based service (LBS). The key technology-positioning-in LBS has been widely applied in scientific research, military, commercial, and many other fields. Radio frequency identification (RFID) technology, with advantages of quick response speed, long identification distance and low cost, combined with wireless sensor networks(WSN), has been widely used in the positioning and management system of goods and personnel.With constant expansion of application fields, the demand of indoor3D positioning is increasing rapidly. However, most currently employed RFID positioning system are limited to2D planar, and some3D positioning system that under study are too complicated to be used, thus, a3D position service with high precision and great real-time response fails to be provided.For providing a practical solution, the thesis aims at finding out a RFID sensor networks positioning method, further developing a relatively simply structure system with high precision and good real-time in actualizing the indoor RFID positioning. The key technology of3D indoor positioning system has been studied, and the main work in this article is as follows:(1) By summaries on the environmental features of the emergency hospitals and analysis on particular requirement that toward the positioning of staff and material, an indoor RFID sensor networks positioning system, including the software and hardware platform, is established subsequently, therefore, experimental environment and verification platform are also built for the research on the positioning methods consequently.(2) Most of traditional RFID positioning systems are limited to2D planar and some of the existing3D positioning systems are complicated. To overcome these defects, a positioning method based on space division using passive RFID was proposed. The location of the target is acquired gradually form2D to3D, and the positioning system has low cost and is not complicated. The positioning precision is higher than the traditional LANMARC system.(3) As the precision demand of3D indoor positioning system in practical application is increasing continually, a target position error modulation method based on gradient decent and residual weighting function was proposed. It can optimize the target location and improve the three-dimensional positioning effectively.Application demonstration in hospital and simulation results of system and method proposed in this article show that it can position the target in3D space in an acceptable range that compared with the classic LANDMARC system, it improved the positioning precision by8times. The positioning precision can be further improved by using the error modulation method with an appropriate initial coordinates.