TagScan

Abstract

Target imaging and material identification play an important role in many real-life applications. This paper introduces TagScan, a system that can identify the material type and image the horizontal cut of a target simultaneously with cheap commercial offthe-shelf (COTS) RFID devices. The key intuition is that different materials and target sizes cause different amounts of phase and RSS (Received Signal Strength) changes when radio frequency (RF) signal penetrates through the target. Multiple challenges need to be addressed before we can turn the idea into a functional system including (i) indoor environments exhibit rich multipath which breaks the linear relationship between the phase change and the propagation distance inside a target; (ii) without knowing either material type or target size, trying to obtain these two information simultaneously is challenging; and (iii) stitching pieces of the propagation distances inside a target for an image estimate is non-trivial. We propose solutions to all the challenges and evaluate the system's performance in three different environments. TagScan is able to achieve higher than 94% material identification accuracies for 10 liquids and differentiate even very similar objects such as Coke and Pepsi. TagScan can accurately estimate the horizontal cut images of more than one target behind a wall.

Material Identification System with Sound Simulation Assisted Method in VR/AR Scenarios

“…Other than the acoustic-based material identification methods, other approaches utilized such as RF signal, pressure and deformation, etc. Wang et al [21] introduced TagScan, a system that can identify the material type and image the horizontal cut of a target simultaneously with cheap commercial off-the-shelf (COTS) RFID devices. However, it could only identify fluid materials and compositions, which cannot meet our demands to identify solid object materials.…”

Capacitivo

“…It can recognize passive and active objects as well as different parts of the body. Furthermore, TagScan [37] identifies different types of liquids using RFID. Unlike the existing work, where objects can only be detected at a single location of a rigid sensor, our technique is designed for soft fabrics to cover a broader surface area.…”

“…To understand how well the proposed technique may work for a wider variety of drinks, we extended our apparatus to six liquids, including Cold Water, Hot Water, Coke, Apple Cider, Milk, and Beer (Pabst blue ribbon). According to prior work [3,37], the permittivity of these liquids varies due to the difference in temperature and also in the concentration of sugar and salt. However, unlike the objects tested in the main study, liquids are different in a much more subtle way.…”