Conflict detection performance of non-cooperative sensing architectures for small UAS sense and avoid

The safe integration of Unmanned Aircraft Systems in the civil airspace requires the development of Sense and Avoid (also named Detect and Avoid) systems, which represent a technology needed to detect a threat (e.g., an intruder vehicle) and, consequently, command a maneuver suitable to avoid collision within a small amount of time. In this framework, this paper presents a quantitative assessment of conflict detection performance achievable by different sensing architectures, which can be designed and installed on board of small Unmanned Aerial Vehicles. The attention is focused on non-cooperative systems, which can rely on active sensors (such as radars and LIDARs), passive sensors (such as visual cameras) or multi-sensor-based solutions. The aim is to quantitatively identify the potentialities and limitations of each technological solution. The analysis is carried out by means of a numerical simulation environment able to reproduce horizontal collision scenarios. Specifically, conflict detection performance is expressed in terms of two probabilities, namely the probability of missed conflict detection and false conflict detection, which are evaluated as a function of three parameters which allow uniquely defining the collision scenario, i.e., the time to and distance at the closest point of approach and the azimuth of the intruder with respect to the velocity vector of the ownship. Since, the probability determination process includes the effect of tracking uncertainties (i.e., probability of firm tracking and false track generation), this analysis also allows highlighting the diverse but interconnected effects of sensing accuracy and detection range.