Real-Time Location Landing Autonomous System Using WiFi Antennas for UAVs

This work proposes a method for assisting the autonomous landing procedure in Unmanned Aerial Vehicles (UAVs) equipped with WiFi transmitter. The system estimates the angular displacement of the UAV with respect to the ground base on the X -axis $\left(\theta_{x}\right)$ and the Y -axis $\left(\theta_{y}\right)$. The angular shift is computed with the acquired RSSI from five commercial directive antennas connected to a WiFi MiMo Acces Point. Therefore, the system does not require phase or complex information. Four antennas in the system are tilted to generate two monopulse functions for estimating the Direction of Arrival (DoA) of the UAV in both axes. A novel two-dimensional DoA method combines several monopulse functions on the same axis. This amplitude monopulse method increases the accuracy and the Field of View of the system with regard to previous individual monopulse works. The field of view of the proposed system is $\left[-40^{\circ} 40^{\circ}\right]$ on each axis $\left(80^{\circ} \times 80^{\circ}\right.$ total), and a mean angular error of 3.22° and 4.34° in the X -axis and Y -axis, respectively, is achieved.