A typical problem for magnetic surveys with small Unmanned Aerial Systems (sUAS) is the heading error caused by undesired magnetic signals that originate from the aircraft. This can be addressed by suspending the magnetometers on sufficiently long tethers. However, tethered payloads require skilled pilots and are difficult to fly safely. Alternatively, the magnetometer can be fixed on the aircraft. In this case, aircraft magnetic signals are removed from the recordings with a process referred to as magnetic compensation, which requires parameters estimated from calibration flights flown in an area with magnetically low-gradients prior to the survey. We present open-source software fully written in Python to process data and compute compensations for two fundamentally different magnetometer systems (scalar and vector). We used the software to compare the precision of two commercially available systems by flying dense grid patterns over a 135 × 150 m area using different suspension configurations. The accuracy of the magnetic recordings is assessed using both standard deviations of the calibration pattern and tie-line cross-over differences from the survey. After compensation, the vector magnetometer provides the lowest heading error. However, the magnetic field intensity recovered with this system is relative and needs to be adjusted with absolute data if absolute intensity values are needed. Overall, the highest accuracy of all suspension configurations tested was obtained by fixing the magnetometer 0.5 m below the sUAS onto a self-built carbon-fiber frame, which also offered greater stability and allowed fully autonomous flights in a wide range of conditions.

中文翻译：

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无人机系统磁力测量：用于评估和比较不同传感器系统、悬架设计和补偿方法的精度的软件

使用小型无人机系统 (sUAS) 进行磁测量的一个典型问题是由来自飞机的不需要的磁信号引起的航向误差。这可以通过将磁力计悬挂在足够长的系绳上来解决。然而，系留有效载荷需要熟练的飞行员并且难以安全飞行。或者，磁力计可以固定在飞机上。在这种情况下，通过称为磁补偿的过程从记录中去除飞机磁信号，这需要从在调查之前在具有低磁梯度的区域飞行的校准飞行估计参数。我们展示了完全用 Python 编写的开源软件，用于处理数据和计算两种根本不同的磁力计系统（标量和矢量）的补偿。我们使用该软件通过使用不同悬挂配置在 135 × 150 m 区域上飞行密集网格图案来比较两个商用系统的精度。使用校准图案的标准偏差和调查中的联络线交叉差异来评估磁记录的准确性。补偿后，矢量磁力计提供最低的航向误差。但是，该系统恢复的磁场强度是相对的，如果需要绝对强度值，则需要使用绝对数据进行调整。总体而言，通过将 sUAS 下方 0.5 m 处的磁力计固定在自建碳纤维框架上，获得了所有测试悬架配置的最高精度，这也提供了更高的稳定性，并允许在各种条件下进行完全自主飞行。