An RFID-Based Wireless Vibration and Physical-Shock Sensing System Using Edge Processing

This article presents energy-efficient edge processing for an ultrahigh-frequency (UHF) band radio-frequency identification (RFID)-based vibration frequency/ physical shock sensing system. This system is especially useful for long-term measurements. In this edge processing system, an RFID reader has a standby mode operating at a low duty cycle and an active mode operating at a high duty cycle. With these modes, an RFID reader achieves both energy-efficient operations and accurate sensing performance. The standby mode is useful for reducing energy consumption, preventing overheating, and reducing greenhouse gas emissions because a low duty cycle leads to a short radio wave irradiation time. Reducing the heat generation of the RFID reader, especially for long-term measurements, the standby mode makes the RFID reader durable. If vibration/physical shocks are applied to the RFID sensor tag, then the standby mode triggers the active mode. The standby mode samples the presence of the RFID sensor tags within an experimentally determined sampling period to detect the beginning of vibration/physical shocks. A high-duty cycle in the active mode results in an increased number of RFID sensor tag readings. Because the proposed edge processing keeps measured data only for the active mode, the amount of data uploaded to the Internet-of-Things (IoT) cloud is reduced. The proposed method was experimentally evaluated by monitoring walking behaviors and a refrigerator. The vibration sensing capability was mainly validated by monitoring a refrigerator, and the physical shock sensing capability was evaluated by monitoring walking behaviors by a human examinee.