TagSense: Robust Wheat Moisture and Temperature Sensing Using RFID

Grain is a major source of food, while grain security has been considered as a strategic issue in many countries. Temperature and moisture as the two key properties affect the quality of stored grain. Most existing approaches for sensing these properties are expensive, time-consuming, and are difficult to deploy. In this paper, we design a TagSense system to sense the temperature and moisture level of stored wheat using commodity RFID devices, where tag’s impedance is exploited as a feature for target sensing at a low cost. Since impedance is sensitive to the signal propagation distance and incidence angle, we propose a distance-independent algorithm and an angle-agnostic approach to mitigate the impact of distance and angles on the sensing performance. Our extensive experiment results demonstrate that TagSense can achieve a satisfactory sensing performance at any distance and any angle within the sensing range.