Tracking of RFID Tags Moving on a Conveyor Belt Using Inverse SAR Approach

摘要

This paper proposes a novel method for tracking the moving items attached with ultrahigh frequency (UHF) radio frequency identification tags (RFID) on a conveyor belt. The localization method is based on phase measurements which is sampled from the radio signal backscattered from the tag antenna to reader antenna. The basic idea behind our method is that a virtual antenna array can be built by exploiting the priori knowledge that the speed and trajectory of the conveyor is known in advance. Thus an inverse synthetic aperture (SAR) can be formed. In order to alleviate the device heterogeneity, phase difference is leveraged to calculate the holographic image, which can be used to reconstruct the tag's absolute trajectory moving on a conveyor belt. Our approach is illustrated in numerical simulations. Finally the performance of our method is also investigated in a real conveyor belt scenario. The experimental results demonstrate that our design is robust to device heterogeneity and is able to achieve fine-grained localization.