Targets tracking by UAVs in an urban area

In this work we address the problem of autonomously tracking a group of ground static targets in an urban area using fixed wing unmanned aerial vehicles (UAVs). In this scenario, UAVs are equipped with sensors that are subject to the constraints of urban area occlusions. Information regarding the line of sight (LOS) occlusions in the urban area is assumed available. Each UAV, considering the dynamic constrains arising from the fixed wing, is modeled as a Dubins car. The motion planning of searching the shortest path for UAVs, namely Dubins path, is a NP hard problem. We propose an algorithm, which can provide sub-optimal Dubins path, hence can bring a closed-loop path for UAVs to continuously track the group of static targets and minimize the time of loss track. The proposed algorithm is validated through simulations on a visual database that is based on the CBD in Singapore.