Soil apparent electrical conductivity (ECa) is a vital metric in Precision Agriculture and Smart Farming, as it is used for optimal water content management, geological mapping, and yield prediction. Several existing methods seeking to estimate soil electrical conductivity are available, including physical soil sampling, ground sensor installation and monitoring, and the use of sensors that can obtain proximal ECa estimates. However, such methods can be either very laborious and/or too costly for practical use over larger field canopies. Robot-assisted ECa measurements, in contrast, may offer a scalable and cost-effective solution. In this work, we present one such solution that involves a ground mobile robot equipped with a customized and adjustable platform to hold an Electromagnetic Induction (EMI) sensor to perform semi-autonomous and on-demand ECa measurements under various field conditions. The platform is designed to be easily re-configurable in terms of sensor placement; results from testing for traversability and robot-to-sensor interference across multiple case studies help establish appropriate tradeoffs for sensor placement. Further, a developed simulation software package enables rapid and accessible estimation of terrain traversability in relation to desired EMI sensor placement. Extensive experimental evaluation across different fields demonstrates that the obtained robot-assisted ECa measurements are of high linearity compared with the ground truth (data collected manually by a handheld EMI sensor) by scoring more than $90\%$ in Pearson correlation coefficient in both plot measurements and estimated ECa maps generated by kriging interpolation. The proposed robotic solution supports autonomous behavior development in the field since it utilizes the ROS navigation stack along with the RTK GNSS positioning data and features various ranging sensors.

翻译：土壤表观电导率（ECa）是精准农业与智慧农业中的关键指标，用于优化水分管理、地质测绘及产量预测。现有多种土壤电导率估算方法，包括物理土壤采样、地面传感器安装与监测，以及利用可获取近端ECa估算的传感器等。然而，这些方法在实际应用于较大冠层区域时，往往过于耗时或成本高昂。相比之下，机器人辅助的ECa测量提供了可扩展且经济高效的解决方案。本研究提出一种采用地面移动机器人的方案，该机器人配备定制化可调节平台，搭载电磁感应（EMI）传感器，可在多种田间条件下进行半自主、按需的ECa测量。该平台在传感器布置方面易于重新配置；通过多案例研究中的可通行性与机器人-传感器干扰测试结果，帮助建立传感器放置的合理权衡。此外，开发仿真软件包可快速便捷地评估与目标EMI传感器布置相关的地形可通行性。在多个田间开展的广泛实验评估表明，与手动手持EMI传感器采集的地面真值数据相比，机器人辅助ECa测量具有高度线性：在样点测量与通过克里金插值生成的ECa估算图中，皮尔逊相关系数均超过90%。所提出的机器人方案利用ROS导航栈、RTK GNSS定位数据及多种测距传感器，支持田间自主行为开发。