Study On Flight Conflict Detection And Resolution Algorithm Of Low-attitude Airspace Based On ADS-B

Flight collision avoidance system is a last resort to resolve conflicts between aircrafts, which is divided into the ground and airborne equipments. Resolution process is coordinately carried out by ground controllers and pilots. However, in the low-altitude and non-controlled airspace, collision avoidance is mainly completed by the subject of flying which depends on airborne TCAS because of free flight in future. New technologies such as ADS-B for general aviation at low-altitude airspace will greatly improve the accuracy of surveillance and provide technical basis for study on the topic that conflict detection and resolution between aircrafts at low-altitude airspace.Firstly, the basic theories of ADS-B system, low-altitude flight and collision avoidance system are introduced, and features of low-altitude flight surveillance where ADS-B system is applied are analyzed from the relationship between ADS-B system and low-altitude flight. Then the perspective that hybrid surveillance by ADS-B and TCAS is future trend of airborne collision avoidance system is pointed out.Secondly, considering the targets confusion and track uncertainty, the algorithm of multi-target and multidimensional filtering before conflict detection and the trajectory prediction algorithm for retained targets after being filtered are proposed. The filtering algorithm for conflicting targets is to preliminarily determine whether there is the possibility of conflict according to the speed, heading and other basic state information of them, and the unpossible conflicting targets are filtered. Effectiveness and necessity of filtering algorithm is proved through Monte Carlo experiments. Trajectory prediction is completed by the strategic prediction and tactical prediction. The long-term track is roughly estimated through strategic perdition and short-term track can be precisely estimated by tactical prediction. Results of simulation have proved that the effect of trajectory prediction algorithm is good.Thirdly, an improved conflict detection algorithm which is applicable to the flight feature of low-altitude airspace is given. The algorithm can effectively and accurately predict the collision probability of surveillance targets, and provide advisory for the target whose value of collision probability is higher than threshold. Then resolution is divided into early route optimization and under hybrid surveillance by ADS-B and TCAS, and early resolution is deeply analyzed based on ADS-B IN technology. Simulation results show that the improved collision detection algorithm has much better detection ability.Finally, a global optimization horizontal resolution algorithm of collision domain is proposed according to ADS-B and TCAS hybrid surveillance. Through two aspects of ideal model and general model considered separately, the different corresponding resolution conditions are acquired. The HRA is the core part of resolution scheme under hybrid surveillance, which can guarantee security of collision targets at the last moment. The validity and reliability of HRA is confirmed by simulation and analysis results.