I. Introduction
Nowadays, unmanned aerial vehicles (UAVs) are witnessing an increasing use in different applications, from military and security services to public and industrial facilities [1], [2]. In this large segment of applications, navigation and path planning are continuing to be a challenging task, especially in urban environments where the UAV is easily vulnerable to collisions. In addition, battery limitations of the UAV adds another factor of complexity to the problem. These elements together make the development of reliable and persistent UAV navigation algorithm be of a great importance.