Urban airspace availability assessment framework and its applications using geometric and topological algorithms

Abstract

With the rapid adoption of operational concepts of Unmanned Aerial Systems (UAS) and Urban Air Mobility (UAM), low-altitude urban airspace has garnered greater attention from governments and industries. This low-altitude airspace contains an existing environment of people and surrounding structures that are inevitably exposed to the risks posed by emerging operations. In such environment, particular parts of airspace may not be available for operational use, in order to provide an acceptable level of safety. This thesis proposes a framework to assess available airspace in which vehicles can safely operate in highly urbanized areas, while incorporating the level of protection to infrastructure as well as operational requirements of vehicles. We define and identify free and available airspace by applying two types of geofencing. In Chapter 2, a significant reduction in the amount of available airspace was observed, even with small geofence parameters. It was also found that urban airspace consists of small and large segments connected to each other. In Chapter 3, we introduce a compact and robust data structure, skeletal graphs, to represent the 3D airspace of complicated geometry. Using skeletal graphs, we examine the topological properties of airspace, including horizontal and vertical connectedness of and among the segments. Topological analysis allows to identify airspace segments that are vulnerable to capacity loss when traffic is concentrated. The proposed skeletal structure can be also utilized for constructing air corridors in which traffic information can be stored and updated, as discussed in Chapter 4. The proposed framework not only is capable of evaluating airspace availability in an adaptive and intelligent manner but also can be adopted to identify departure/arrival locations and assess the capacity of urban airspace.