Research On Flight Safety Separation Control Technology Of Task-oriented Unmanned Aerial Vehicle Formation

The increasing congestion of the ground traffic environment and the pursuit of more convenient and high-quality life have inspired people’s enthusiasm to use low altitude airspace.The unmanned aerial vehicle(UAV)industry is developing rapidly.With the continuous maturity of civil drone technology,it is possible to use drone formation for logistics transportation.UAV formations are faster and more flexible than traditional logistics methods.The use of drone formations can greatly improve the efficiency of logistics.However,there are still some problems to be solved in the current logistics UAV formation technology.The logistics drone formations have small flight separation and are easy to conflict with each other.And it is complicated to plan and calculate.In response to these problems,this paper focuses on the safety separation control technology based on the event trigger mechanism.This paper mainly focuses on the rapid identification technology of formation unsafe separation and the re-planning technology of formation trajectory.The unsafe separation detection inside the logistics drone formation is transformed into a pattern recognition problem.We use the Monte Carlo method to build a conflict database.The key feature indicators of the conflict are refined and a probabilistic neural network is constructed based on the key features.Then,the conflict database is learned by the neural network.The simulation results show that the method can realize real-time identification of unsafe separation within large-scale UAV formations.And the recognition accuracy is high.Then,trajectory planning technology is used to solve the problem of safety separation control of logistics UAV formation.The re-planning of the formation trajectory is divided into two steps:path planning and speed planning.In terms of path planning,the preview distance adaptive algorithm is constructed to achieve an effective balance between the path length,turning frequency and tracking error.The control parameterization and time discretization(CPTD)method was improved during the speed planning process.A differential zone velocity planning method under rasterized airspace(DIPR)is proposed and the algorithm is improved.The simulation results show that the proposed method can improve the efficiency and quality of speed planning while increasing the minimum separation of trajectories.Moreover,the calculation result of the minimum separation of the trajectory by the DIPR method is more accurate,which makes the trajectory more secure.