Comprehensive Risk-based Planning for Small Unmanned Aircraft System Rooftop Landing

The expected proliferation of Unmanned Aircraft Systems (UAS) has prompted many to question their safety and reliability, particularly in urban areas. Failures and anomalies can lead to the need for emergency landing, which in turn requires the UAS operator or autonomy to rapidly identify and evaluate the risks for possible landing sites and trajectories to reach these sites. This paper proposes a method to optimize the overall emergency landing site and flight path risks. Although sensors can scan an immediate area, no safe site might be observable in which case pre-processed data on more distant safe sites is required. For example, in urban regions, out of sight flat rooftops may pose less risk to people and property than landing in streets or sidewalks. This paper proposes the offline construction of a landing site database using a variety of public data sources, uniquely allowing for the assessment of risk associated with a rooftop landing. A real-time map-based planner is presented that demonstrates a novel trade-off between landing site risk and path risk and provides a heuristic to improve decision-making efficiency.