| RFID technology is a wireless non-contact system, which uses electromagnetic waves to transmit data from a tag attached to an object, so as to achieve automatic identification and tracking. In recent years, with the rapid development and wide application of RFID technology, the research on object positioning and tracking gets more and more attention of scholars at home and abroad. As the most closely ocaasion in human production and life, the research on indoor positioning has an important practical significance. However, the traditional positioning technology can not meet environmental requirements due to the complex indoor environment. For its high accuracy, low latency, non-contact, low cost and other characteristics, RFID indoor wireless positioning technology becomes the preferred technique for indoor positioning. It can work in converting station intelligent management, mine positioning and other industrial areas, besides that, it can be also applied to common civil areas and military areas, such as vistor control、position information achievement in shopping malls and airports、the prision and defend. With the gradual improvemrnt of quality of life, people’s demand for location information is more and more urgent. But the existing RFID positioning systems still have many problems on positioning, cost and accuracy and other aspects, such as high positioning errors, high system costs and so on.To solve the existing problems of the current RFID positioning technology, this paper studies the indoor wireless positionging control method based on RFID, and the work mainly includes the following four aspects:(1) This paper takes RFID as the technical realization of indoor positioning and respectively introduces the development process, research status and future trends of the wireless positioning technology, RFID technology and RFID positioning technology.(2) This section describes the indoor positioning technology-related works in detail, including indoor positioning algorithm mathematical models based on distance and their respective advantages and disadvantages; the more popular indoor wireless positioning technology and the particle filter used for indoor wireless location tracking problem of nonlinear model.(3) Aiming at the problems of slow data transmission, high system costs, and low location precision in RFID positioning system, an indoor positioning hybrid approach of Ultra High Frequency RFID is proposed in this paper. This approach takes the Angle of Arrival as the core and integrates the idea of Time Difference of Arrival. Moreover, the stepping motor is used instead of antennas array to make Ultra High Frequency RFID reader whirl around an axis with a constant angular rate. Therefore, it is easy to scan each tag and estimate their locations. The results indicate the improved algorithm acquires better positioning performance than separate positioning algorithm above.(4) Finally, to address the difficulty in tracking indoor mobile targets, applying Particle Filter algorithm to estimate target state. However the particles are easy to loss the diversity, so a RFID indoor tracking algorithm based on improved particle filter is proposed. It treats Received Signal Strength Indication values received from readers as observation parameter directly to establish a nonlinear state space model, while a new adaptive partial systematic resampling algorithm with Markov chain Monte Carlo move step is presented. The new algorithm resamples after classifying the particles with a measure function and the MCMC move step is joined after resampling steps to improve the diversity of particles. Applying the improved algorithm to simulate the nonlinear single variable static model and nonlinear tracking model mentioned above, and compared with other resampling measures, the improved algorithm performs better. |
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