UAV Remotely-Powered Underground IoT for Soil Monitoring
Yu Luo, Lina Pu
Abstract
This article introduces a practical approach to wirelessly charge underground Internet of Things (IoT) (UIoT) for soil monitoring using ultra-high-frequency (UHF) radio energy. In the proposed system, UIoT nodes do not require batteries or any aboveground attachments (e.g., solar panel). Instead, they harvest 915 MHz radio energy emitted from a UAV for semiperpetual operation. The UIoT nodes utilize the harvested energy to measure soil parameters and transmit data back to the UAV using ZigBee protocol. After collecting the data from UIoTs, the UAV uploads it to a cloud server for online soil quality analysis. The system has been optimized for efficient operation, with a UAV transmit power as low as 2 W. Startup, drive, and power management circuits have been designed to ensure reliable operation of UIoT nodes, even with low incident energy. According to experimental results, the developed radio frequency charging-enabled underground IoT system can successfully power up and transmit more than 1 kB of data within 10 s of wireless charging, followed by an additional 1.7 kB of data every 1.6 s thereafter.