Aircraft Avoidance of Suborbital Debris Hazard Zone Based on Lazy Theta* Algorithm

During the intensive launch of suborbital vehicles, in order to meet the demand of short flight distance of civil aircraft and low workload of controllers, this paper proposes a redirect path planning method for suborbital debris hazard area based on Lazy Theta* algorithm. First, this paper uses the covariance propagation method to predict the propagation range of debris in a suborbital disintegration accident, converts the debris equation of motion into Gauss-Markov process, and constructs a probability ellipsoid using a probability density function to characterize the debris distribution. Second, this paper determines the mathematical boundaries of the projection of the probability ellipsoid of suborbital debris in the horizontal direction according to the acceptable risk probability for civil aviation and adopts the Divide-and-Conquer approach to delineate and extend the boundary of the suborbital debris hazard zone. Third, this paper considers constraints such as turning angle, flight segment length, and rerouting point, and uses the Lazy Theta* algorithm to plan a path with a short path length and few turns. Finally, the simulation results demonstrate that this method can quickly and effectively predict the propagation process of disintegrated debris of suborbital vehicles in complex atmospheric environments; in comparison with A* algorithm, the rerouting path length designed by the Lazy Theta* algorithm is reduced by an average of 2.35% and the number of rerouting points is reduced by an average of 92.04%, which meets the requirements of air traffic control.