Conflict Detection and Resolution

Rule-Based Conflict Resolution for Mixed Airspace

In most cases, UAVs are operated by preprogrammed decisions or remotely controlled by an operator from the ground or in the chasing aircraft. For that reason, UAVs have the possibility of being uncontrollable from unexpected events such as system failure and loss of data link, and threaten civilian aircraft. Currently, air traffic in airport areas are controlled by Air Traffic Control and aircraft in mid air operate under the Federal Aviation Regulations (FAR). To fly UAVs within the National Air Space, UAVs are required to meet an equivalent level of safety to manned aircraft in order not to interfere with civilian or commercial aviation or violate current air traffic control procedures in the National Air Space. In order to support the successful use of mixed airspace, conflict resolution act upon the extended flight rules (EFR) has been studied.

At this time, the EFR for the conflicts between two aircrafts in horizontal and vertical maneuver are developed. The EFR is based on the 'Right-of-way' rules of FAR and the extended rules for the FREER (Free-Route Experimental Encounter Resolution) project of the Eurocontrol. The concept of the EFR is to assign a priority to the aircrafts based on their current flight phase and the distance to the conflict (or the speed) of each aircraft. Also, conflicts for the above cases are solved by geometric optimization. For the conflicts in the horizontal maneuvers, the aircraft which has less priority alternate its path using heading angle change or heading angle and velocity change to avoid the overlapping of the protected zones of the aircrafts. Similarly, for the vertical maneuvers, change of the trajectory change point is used as a resolution method.

Sample figures of the simulation results for two aircrafts: