Target Tracking by UAVs Under Communication Constraints in an Adversarial Environment

In this paper, we present a cooperative strategy for multiple UAVs under communication constraints to follow a moving target in an area with multiple threat sources. The main goals of the cooperative strategy are, (i) to ensure that UAVs do not enter restricted regions (ii) to maintain the pursuit of the target by at least one UAV (iii) to minimize the threat exposure level of each UAV (iv) to maintain the relative distance between UAVs within the communication range, and (v) to generate commanded heading and speed within the dynamic constraints of each UAV. Exposure of the UAVs to threat is modelled by using multidimensional Gaussian Law. When the UAVs are within the communication range, they send their own position and target measurements to other UAVs. The time delay during the data transmission between the UAVs is taken into account by the strategy and estimation algorithm. During the pursuit, the UAVs estimate the position of the target using the position measurements of both UAVs if they are within the communication range. When the target is out of a UAV sensor range, that UAV uses the information from the other UAV as long as they are within communication range. When the UAVs are out of communication range, they only use their measurements. The linear least-squares estimation is used to estimate the position and to predict the target position by processing the position measurements considering the time-delay. Speed and heading of the target was also calculated from the estimated positions by using kinematic equations.