A Fast UHF RFID Localization Method Using Unwrapped Phase-Position Model

A novel ultrahigh-frequency (UHF) radio frequency identification (RFID) localization method is proposed in this paper, by which the location of a static passive tag can be easily obtained using a mobile RFID antenna. An unwrapped phase-position model with three parameters is built, and the location of the tag can be pinpointed through an ordinary nonlinear least-squares algorithm. The main advantage of this method is that it is cheap in computation cost compared with the existing grid-based methods. The experimental tests confirm that the proposed method can localize the RFID tags with a competitive computational efficiency and accuracy performance, i.e., millisecond-level computing time and centimeter-level location accuracy. The proposed UHF RFID localization method is well suited to the pervasive location-aware applications, searching RFID-tagged item in the intelligent warehouse by the mobile robot with an onboard RFID system, for example. Note to Practitioners Ultrahigh-frequency (UHF) radio frequency identification (RFID) has become an efficient booster for the warehouse logistics management due to its low cost, battery-free, and unique identification. The location-aware technology based on RFID is an enabling technology for intelligent warehouse logistics. This paper proposes a passive UHF RFID tag localization method, by which the tags can be easily localized by the use of a mobile RFID system. The experimental results show that the proposed method can localize the static tags with good performance, especially low computation cost. The proposed localization method contributes to the pervasive location-aware application, in which their computation ability is usually limited. For example, mobile robots with the RFID system autonomously seek the RFID-tagged stocks in a warehouse.