Hierarchical Four-Dimensional Trajectories Planning Method for Manned and Unmanned Aircraft Integrated Airspace

A waypoint-based trajectory planning framework is proposed. The motivation is to allocate capacity-constrained airspace resources for pretactical safe separation in the manned and unmanned aircraft integrated airspace. First, the spatial-temporal related aircraft with high conflict risks are clustered to reduce the scale of the problem induced by increasing traffic volumes. A two-stage optimization is further implemented. In the first stage, trajectories within each group are sequentially planned in order determined by a priority ranking mechanism, where the relative conflict-critical aircraft takes more deconflicting responsibilities. A distributed decision-making architecture is developed to account for aircraft heterogeneity in the sequential deconflicting process. In the second stage, the high-quality solutions of different groups are coupled together to obtain the overall trajectory distribution under system-wide resource capacity constraints. Empirical studies using operational data in China show that the proposed method reduces 95% of conflicts with low cost and few aircraft disturbance, which demonstrate superiority in deconflicting effectiveness and efficiency. In addition, the distributed decision-making process ensures scalability and flexibility by allowing aircraft to determine the optimal trajectories based on their internal tradeoffs. Several major conclusions and future work are presented based on the current investigation.