We study the problem of tracking mobile targets using a team of aerial robots. The robots are mounted with cameras that face downwards, and are used to detect targets moving on the ground. The overall goal is to plan for the trajectories of the robots in order to track the most number of targets, and accurately estimate the target locations using the images. The two objectives can conflict since a robot may fly to a higher altitude, thus potentially covering a larger number of targets but with lower accuracy.
We start by showing that k>= 3 robots may not be able to track all n targets while maintaining a constant factor approximation of the optimal quality of tracking at all times. Next, we study the problem of choosing robot trajectories to maximize either the number of targets tracked or the quality of tracking. We formulate this problem as a weighted, combinatorial optimization problem. A greedy algorithm yields a 1/2 approximation for this problem. Finally, we evaluate the algorithm and the sensing model through simulations and preliminary experiments.