On-the-Fly Coordination of Maneuvers for Separation Assurance of UAM Aircraft in Congested Airspace

Urban air mobility (UAM) is an emerging aviation concept envisioned to provide urban transportation with safe and on-demand air travel for both passengers and cargo. In UAM, maintaining a minimum separation between aircraft is a safety requirement that becomes challenging to meet amidst congested air traffic and off-nominal conditions, such as Loss of Control In-flight (LOC-I) of aircraft. Often, separation loss caused by LOC-I results in subsequent separation losses, triggering domino effects as one aircraft maneuvers to avoid another aircraft experiencing LOC-I in congested air traffic. This paper therefore presents an on-the-fly, integrated decision-making and trajectory planning framework to address the separation losses caused by LOC-I. A Behavior Tree-based decentralized decision-making is employed to execute a separation assurance task assigned by the provider of service to UAM (PSU), coordinating and selecting the necessary maneuvers based on Federal Aviation Administration (FAA) right-of-way rules to resolve the encountered separation losses. To execute the selected maneuver, an optimization-based receding horizon trajectory planning is employed to generate safe and optimal trajectories by taking into account the aircraft dynamics, maneuver direction, and minimum safe separation distance between aircraft. Further, a UAM simulation environment is developed for verification and testing of UAM traffic management algorithms, allowing the implementation of on-the-fly conflict detection, tasking, and planning algorithms to resolve the separation losses. The effectiveness of the proposed framework is demonstrated by considering various separation loss scenarios arising from LOC-I, such as overtaking, converging, and head-on separation losses, within the developed UAM simulation environment.