A Phase-Based Technique for Localization of UHF-RFID Tags Moving on a Conveyor Belt: Performance Analysis and Test-Case Measurements

TLDR

The authors introduce a phase‑based method for localizing and tracking UHF‑RFID tags on a conveyor belt, and validate its feasibility. The method employs a synthetic‑array radar framework that leverages known belt speed and path, combines synthetic‑array principles with knowledge‑based processing and reader‑tag signal exploitation, and can be implemented on standard readers without antenna changes. Experimental results on a real conveyor demonstrate centimeter‑level tag position accuracy even in a rich multipath environment.

Abstract

A new phase-based technique for localization and tracking of items moving along a conveyor belt and equipped with ultrahigh frequency-radio frequency identification (UHF-RFID) tags is described and validated here. The technique is based on a synthetic-array approach that takes advantage of the fact that the tagged items move along a conveyor belt whose speed and path are known a priori. In this framework, a joint use is done of synthetic-array radar principles, knowledge-based processing, and efficient exploitation of the reader-tag communication signal. The technique can be easily implemented in any conventional reader based on an in-phase and quadrature receiver and it does not require any modification of the reader antenna configurations usually adopted in UHF-RFID portals. Numerical results are used to investigate the performance analysis of such methods, and also to furnish system design guidelines. Finally, the localization capability is also demonstrated through a measurement campaign in a real conveyor belt scenario, showing that a centimeter-order accuracy in the tag position estimation can be achieved even in a rich multipath environment.