Research On Multi-UAV Cooperative Trajectory Planning Based On Improved PRM Algorithm

Multi-UAV collaborative path planning,as one of the key technologies of UAV collaborative task control,forms the basis of multi-machine interaction capability,It is of great significance to improve the survivability in the aircraft battlefield and multi-machine cooperative combat effectiveness.Based on the improved Probabilistic Path Maps(PRM)algorithm,this paper studies the stand-alone planning and multi-UAV cooperative planning.Firstly,we establish the UAV trajectory planning model according to the practical operational requirements,which is solve by the improved PRM algorithm.In order to solve the problem of collaborative planning,the centralized pre-planning collaborative strategy and decentralized re-planning coordination strategy are designed,and finally the function and performance of the algorithms and strategies analyzed and verified through simulation.The study provides a technical idea for multi-aircraft collaborative trajectory planning.The main research work and innovations are summarized as follows:(1)Establishing a UAV trajectory planning model.Through the analysis of the battlefield environment,the model of battlefield threat is established and the comprehensive cost evaluation function is given.The description of maneuverability constraints of UAV taken into consideration,the UAV trajectory planning model is established.(2)Designing a track planning method based on the improved PRM algorithm.Aiming at resolving the shortcoming of PRM algorithm in terms of high time complexity during the collision detection process,a composition strategy based on complete random sampling is devised.It not only avoids the collision detection of the composition stage,but also uses route search in the query phase considering the threat cost of the obstacle to avoid the obstacle,It ultimately avoids the shortcomings of the regenerative or local reconstruction of the road map when the dynamic changes of the threat barrier are made.The improved PRM algorithm is applied to static track pre-planning and local track re-planning respectively,Simulation results show that the improved PRM algorithm increases the efficiency of track planning.(3)Designing a centralized planning coordination strategy and re-planning coordination strategy based on decentralized control.The time coordination requirements of UAVs is considered in the centralized pre-planning collaborative strategy,a double-layer(collaborative planning layer and track planning layer)control structure is designed to achieve the lowest cooperation cost flight path and speed for each UAV.As for the influence of the sudden threat to the multi-machine coordination in task execution,a decentralized coordination re-planning strategy is designed.The coherence algorithm is used to coordinate the flight speed of the unmanned aerial vehicles after the sudden threat to achieve the goal of simultaneous arrival.The simulation results verify the effectiveness of the planning algorithm and the cooperative strategy.