Novel Bridge-Loop Reader for Positioning With HF RFID Under Sparse Tag Grid

We propose a novel method of positioning using a high-frequency radio-frequency identification (HF RFID) system for navigating autonomous vehicles when a sparse grid of floor tags is employed. For this, we propose a novel triangular multiloop-bridge reader antenna which generates an error signal in the form of bridge potential that is a function of the tags´ location. The proposed positioning algorithm combines the information from the reader database with the error signals generated by the bridge loop and couples them with any available data from the wheel encoders of an autonomously moving object to deduce its position and orientation. The accuracy and efficacy of the proposed algorithm are evaluated using both simulations and experiments using an autonomous wheelchair. The results indicate that the proposed method offers a significant improvement over existing HF-RFID-based positioning methods for larger floor-tag-grid separation.