Virtual sensors for smart farming: An IoT- and AI-enabled approach

Smart farming relies on precise environmental data to optimize agricultural practices, with key metrics such as air temperature, humidity, rain, ambient light, ultraviolet (UV) radiation and soil moisture to play a crucial role in agricultural decision-making. However, the vast spatial coverage of agricultural fields and the high cost of deploying numerous physical sensors pose significant challenges, particularly for small and medium-sized farms. To address these issues, virtual sensors – machine learning models that predict sensor values based on data from relevant physical sensors – offer a cost-effective and scalable alternative. In this research, a number of Arduino-based IoT devices are designed and deployed equipped with various physical sensors, a lithium-polymer battery which recharges continuously using a 6 W waveshare solar panel, and a Real-Time Clock (RTC) module that synchronizes data logging. The IoT devices operated across two agricultural fields over a span of almost three months. The data collected form the basis for evaluating multiple machine learning models as virtual sensors. Furthermore, the use of open weather data to develop a hardware-free solution is explored. Experimental results show that virtual sensors provide a cost-effective and accurate method for replacing physical sensors. The Light Gradient Boosting Machine emerged as the most accurate model for virtual sensors, achieving prediction errors of less than 1% in most of the cases. This makes it a valuable tool for enabling cost-effective and data-driven farming in resource-constrained IoT devices.