Research On Cooperative Task Assignment Method Based On UAV Formation

With the constant advances in unmanned aerial vehicles’ s technology and the rapid development of automation,unmanned aerial vehicles(UAVs)are becoming increasingly intelligent and their application scope is gradually broadened,especially in the military field.In line with the development of the contemporary trend,multi-UAV collaborative operation has attracted great attention from countries all over the world because it can improve the survival probability and mission efficiency of UAV,and multi-UAV collaborative task allocation is the foundation and key of multi-UAV collaborative operation.In this thesis,the collaborative task assignment problem of multi-UAV in dynamic environment is studied.Firstly,the related technologies of multi-UAVs collaborative task allocation are introduced,and several commonly used mathematical models and optimization algorithms are described and analyzed in detail.According to the characteristics and requirements of multi-UAV cooperative operation,the formation configuration of UAV formation is studied,and the drag reduction strategy of UAV formation is introduced.The cost function model,the gained benefit function model and the mission effectiveness model based on the cost function and benefit function are established under various constraints.Then,on the basis of the model,the improved contract network algorithm is used to solve the mathematical model.The contract net protocol realizes the task assignment among cooperators through four stages of "bid inviting-bidding-winning-signing".The traditional contract net protocol has some shortcomings in the selection of bidding task,the way and scope of bidding task publication,the conditions for bidders to participate in bidding and the bidding evaluation method of bidders,which leads to the heavy workload of UAV,the low efficiency of task allocation and the low efficiency of the system.Aiming at the problems existing in the traditional contract network algorithm,this thesis proposes an improved contract net protocol,including task selection strategy,bidding scope selection strategy,bidding strategy and bid evaluation method.According to the task urgency degree in the task selection strategy and the workload situation of the UAV,priority is given to the relatively urgent and heavy workload tasks for release;Before the bidding,the comprehensive capability of UAVs is evaluated,and UAVs with higher comprehensive capability are selected.Only those UAVs with higher comprehensive capability will be released the bidding information.The UAV that receives the bidding information will determine whether it becomes a bidder to participate in the bidding according to the bidding strategy;Finally,the bidder evaluates the bidding documents of the bidders according to the bidding evaluation method,determines the winning bidder and signs the contract.Finally,MATLAB simulation software is used to simulate and analyze the improved algorithm.The simulation results show that compared with the traditional contract net protocol,the improved contract net protocol not only balances the workload of the UAV system,but also significantly improves the task efficiency of the system.