Understanding Safety for Unmanned Aerial Vehicles in Urban Environments

When Unmanned Aerial Vehicles (UAVs) autonomously operate in urban environments, it is especially important for these systems to behave safely and not harm anybody or anything. However, it is challenging to ensure that these systems behave safely in all possible situations and to clearly define this "safe" behavior for each situation. In this work, we provide a methodology for testing the safe behavior of UAVs while considering their environment with the help of scenario-based testing and search-based techniques. Additionally, we explore two cases throughout the paper: (i) A safety distance is specified, and we can use it for testing. (ii) No safety distance is defined, but we still aim to test the safe behavior of UAVs. In our experiments, we show the effectiveness and applicability of the proposed methods by discovering several safety distance violations and questionable behaviors of the tested UAV for both cases and four scenarios that represent all alternatives to avoid an obstacle.