Paolini Giacomo, Guermandi Marco, Masotti Diego, Shanawani Mazen, Benassi Francesca, Benini Luca, Costanzo Alessandra
DEI-Department of Electrical, Electronic and Information Engineering "Guglielmo Marconi", University of Bologna, 40136 Bologna, Italy.
ARCES-Advanced Research Center on Electronic Systems "Ercole De Castro", University of Bologna, 40125 Bologna, Italy.
Sensors (Basel). 2021 Jan 8;21(2):386. doi: 10.3390/s21020386.
This work describes the design, implementation, and validation of a wireless sensor network for predictive maintenance and remote monitoring in metal-rich, electromagnetically harsh environments. Energy is provided wirelessly at 2.45 GHz employing a system of three co-located active antennas designed with a conformal shape such that it can power, on-demand, sensor nodes located in non-line-of-sight (NLOS) and difficult-to-reach positions. This allows for eliminating the periodic battery replacement of the customized sensor nodes, which are designed to be compact, low-power, and robust. A measurement campaign has been conducted in a real scenario, i.e., the engine compartment of a car, assuming the exploitation of the system in the automotive field. Our work demonstrates that a one radio-frequency (RF) source (illuminator) with a maximum effective isotropic radiated power (EIRP) of 27 dBm is capable of transferring the energy of 4.8 mJ required to fully charge the sensor node in less than 170 s, in the worst case of 112-cm distance between illuminator and node (NLOS). We also show how, in the worst case, the transferred power allows the node to operate every 60 s, where operation includes sampling accelerometer data for 1 s, extracting statistical information, transmitting a 20-byte payload, and receiving a 3-byte acknowledgment using the extremely robust Long Range (LoRa) communication technology. The energy requirement for an active cycle is between 1.45 and 1.65 mJ, while sleep mode current consumption is less than 150 nA, allowing for achieving the targeted battery-free operation with duty cycles as high as 1.7%.
本文描述了一种用于在富含金属、电磁环境恶劣的条件下进行预测性维护和远程监测的无线传感器网络的设计、实现及验证。通过一个采用共置的三个具有保形形状的有源天线系统，在2.45 GHz频率上无线供电，该系统能够按需为位于非视线（NLOS）和难以到达位置的传感器节点供电。这消除了定制传感器节点的定期电池更换需求，这些传感器节点设计得紧凑、低功耗且坚固耐用。在实际场景（即汽车发动机舱）中开展了测量活动，假设该系统应用于汽车领域。我们的工作表明，在照明器与节点之间距离为112厘米（NLOS）的最坏情况下，一个最大有效全向辐射功率（EIRP）为27 dBm的单射频（RF）源（照明器）能够在不到170秒的时间内传输4.8 mJ的能量，以完全为传感器节点充电。我们还展示了在最坏情况下，传输的功率如何使节点每60秒运行一次，其中操作包括1秒的加速度计数据采样、提取统计信息、传输一个20字节的有效载荷，并使用极其稳健的长距离（LoRa）通信技术接收一个3字节的确认。一个活动周期的能量需求在1.45至1.65 mJ之间，而睡眠模式下的电流消耗小于150 nA，这使得在占空比高达1.7%的情况下能够实现无电池运行的目标。
