A Trajectory Control Strategy for any Number of UAVs in Passive Localization of Radio Sources

In this paper an optimal trajectory control strategy is presented for single and multiple unmanned aerial vehicles (UAVs) equipped with received signal strength (RSS) sensors to localize a stationary RF source. The RSS at each UAV is observed in specified time instances. Due to the additive Gaussian noise caused by the non-line of sight (NLOS) propagation condition the location of the source is estimated using the extended Kalman filter (EKF). The objective is to determine the waypoints of the UAVs that minimize the source location uncertainty. The determinant of the Fisher information matrix (FIM) which is inversely proportional to estimation variance is applied to generate UAVs’ trajectories. The FIM is approximated at successive waypoints according to the estimated source location. To compensate the lack of adequate number of sensors when applying one or two UAVs the previous information is included in FIM calculations. The effectiveness of the proposed approach is depicted in simulation examples.