Isotropic and Directional DOA Estimation of the Target by UAV Swarm-based 3-D Antenna Array

In this paper, the efficient use of swarm UAVs as a flying three-dimensional (3-D) antenna array is explored. In particular, we propose a method consisting of both azimuth and elevation (2-D) DOA estimation, tracking, and intervention of the unwelcome target via UAVs swarm-based antenna array. Firstly, UAVs swarm fly in a 3-D polyhedral formation that can provide 2-D isotropic DOA estimation to detect a target with curvilinear motion with variable-velocity. In the second step, once the target is detected, the swarm transition to the formation of the ULA antenna array with high antenna array gain. Finally, in the intervention phase, the swarm transition to the formation of the UCA antenna array in order to surround the target. In order for providing energy sensitive formation switching during each phase transition, we also applied the Jonker-Volgenant (JV) global nearest neighbor assignment algorithm to the re-formation of the swarm with the shortest total path. Simulation results show that the detection, tracking, and intervention of randomly moving targets can be done effectively with swarm-based antenna array formations.