Wi-Fi CSI-Based Foreign Object Detection in Designed Areas Under Vehicle Bodies Using L-Shaped Directional Antennas for Wireless Power Transfer

In wireless power transfer (WPT) systems for electric vehicles, metallic foreign objects near the power supply unit can overheat and pose ignition risks. Detecting such objects and shutting off the power is critical. Our previous study revealed that Wi-Fi channel state information (CSI) changes significantly when metallic foreign objects pass close to the antennas. In this study, we evaluated detection accuracy using an L-shaped directional antenna setup around a designed area representing a power supply unit. The detection accuracy of foreign objects was compared between the 2.4 GHz and 5 GHz bands using two types of antenna arrangement with and without an aluminum plate simulating a vehicle. The results showed that while the differences in accuracy owing to antenna arrangement and the presence or absence of the aluminum plate were very small, the detection accuracy was lower in the 2.4 GHz band than in the 5 GHz band.