Electrical Engineering Department, Faculty of Engineering, The Hashemite University, Zarqa 13133, Jordan.
Computer Systems Institute, 529 Main Street, Charlestown, MA 02129, USA.
Sensors (Basel). 2023 Feb 13;23(4):2100. doi: 10.3390/s23042100.
This paper focuses on building a non-invasive, low-cost sensor that can be fitted over tree trunks growing in a semiarid land environment. It also proposes a new definition that characterizes tree trunks' water retention capabilities mathematically. The designed sensor measures the variations in capacitance across its probes. It uses amplification and filter stages to smooth the readings, requires little power, and is operational over a 100 kHz frequency. The sensor sends data via a Long Range (LoRa) transceiver through a gateway to a processing unit. Field experiments showed that the system provides accurate readings of the moisture content. As the sensors are non-invasive, they can be fitted to branches and trunks of various sizes without altering the structure of the wood tissue. Results show that the moisture content in tree trunks increases exponentially with respect to the measured capacitance and reflects the distinct differences between different tree types. Data of known healthy trees and unhealthy trees and defective sensor readings have been collected and analysed statistically to show how anomalies in sensor reading baseds on eigenvectors and eigenvalues of the fitted curve coefficient matrix can be detected.
本文专注于构建一种非侵入式、低成本的传感器，可以安装在半干旱地区生长的树干上。它还提出了一种新的定义，用数学方法描述了树干的保水能力。设计的传感器测量其探头之间的电容变化。它使用放大和滤波级来平滑读数，需要很少的功率，并且在 100 kHz 频率下工作。传感器通过网关通过长距离 (LoRa) 收发器将数据发送到处理单元。现场实验表明，该系统能够提供准确的水分含量读数。由于传感器是非侵入式的，它们可以安装在各种大小的树枝和树干上，而不会改变木材组织的结构。结果表明，树干中的水分含量与测量的电容呈指数增长，反映了不同树种之间的明显差异。已经收集和统计分析了已知健康树木和不健康树木以及有缺陷传感器读数的数据，以展示如何根据拟合曲线系数矩阵的特征向量和特征值检测传感器读数异常。
