An accurate close-range positioning and navigation system is the key to autonomous cruise and the fine operations of multi-rotor UAVs. In this paper, a dynamic electromagnetic positioning system is designed and implemented to accurately navigate a UAV to a very small landing zone. The system is composed of three quasi-static electromagnetic field generators (EGs) installed around the landing zone, and one electromagnetic field sensor (ES) mounted on the UAV. The ES adaptively controls its gain and adjusts the power of the EGs, so it can detect electromagnetic signals under a high SNR (signal-to-noise ratio) condition and has an anti-saturation ability. Consequently, the coordinate and azimuthal angle of the UAV can be measured during the process of the UAV approaching the landing zone. Hardware experiments demonstrate that the prototype system can effectively navigate a UAV to a small landing zone that is slightly larger than the size of the UAV, and the terminal positioning error is less than 2 cm.

中文翻译：

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用于多旋翼无人机精确近距离导航的动态电磁定位系统

精准的近距离定位导航系统是多旋翼无人机自主巡航和精细作业的关键。在本文中，设计并实现了一种动态电磁定位系统，以将无人机准确导航到非常小的着陆区。该系统由安装在着陆区周围的三个准静态电磁场发生器（EG）和一个安装在无人机上的电磁场传感器（ES）组成。ES自适应地控制其增益并调整EG的功率，因此它可以在高SNR（信噪比）条件下检测电磁信号并具有抗饱和能力。因此，可以在无人机接近着陆区的过程中测量无人机的坐标和方位角。