Computer Architecture Department, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain.
Independent Researcher, 08034 Barcelona, Spain.
Sensors (Basel). 2022 May 23;22(10):3964. doi: 10.3390/s22103964.
The use of low-cost sensors in conjunction with high-precision instrumentation for air pollution monitoring has shown promising results in recent years. One of the main challenges for these sensors has been the quality of their data, which is why the main efforts have focused on calibrating the sensors using machine learning techniques to improve the data quality. However, there is one aspect that has been overlooked, that is, these sensors are mounted on nodes that may have energy consumption restrictions if they are battery-powered. In this paper, we show the usual sensor data gathering process and we study the existing trade-offs between the sampling of such sensors, the quality of the sensor calibration, and the power consumption involved. To this end, we conduct experiments on prototype nodes measuring tropospheric ozone, nitrogen dioxide, and nitrogen monoxide at high frequency. The results show that the sensor sampling strategy directly affects the quality of the air pollution estimation and that each type of sensor may require different sampling strategies. In addition, duty cycles of 0.1 can be achieved when the sensors have response times in the order of two minutes, and duty cycles between 0.01 and 0.02 can be achieved when the sensor response times are negligible, calibrating with hourly reference values and maintaining a quality of calibrated data similar to when the node is connected to an uninterruptible power supply.
近年来，将低成本传感器与高精度仪器结合用于空气污染监测已显示出可喜的成果。这些传感器的主要挑战之一是其数据的质量，因此主要努力集中在使用机器学习技术对传感器进行校准，以提高数据质量。但是，有一个方面被忽视了，即这些传感器安装在节点上，如果是电池供电，则可能存在能源消耗限制。在本文中，我们展示了常见的传感器数据采集过程，并研究了这种传感器的采样、传感器校准的质量以及所涉及的功耗之间的现有权衡。为此，我们在原型节点上进行了实验，以高频测量对流层臭氧、二氧化氮和一氧化氮。结果表明，传感器采样策略直接影响空气污染估计的质量，并且每种类型的传感器可能需要不同的采样策略。此外，当传感器的响应时间为两分钟左右时，可以实现占空比为 0.1，而当传感器的响应时间可以忽略不计时，可以实现占空比为 0.01 到 0.02，通过每小时的参考值进行校准，并保持与节点连接到不间断电源时相似的校准后数据质量。
