Energy Efficient Mechanism Of Flapping-Wing Aerial Vehicles In Formation Flight

With the rapid development of bionic techniques,bionic robots have attracted more and more attention among researchers all over the world.As a newly emerging branch in the field of bionic robots,the flapping-wing aerial vehicle(FWAV)has many advantages,such as,light weight,agility,low energy consumption and concealment.It is capable of flying stably at low altitude for a long time.Therefore,the FWAV has broad application prospects in the fields of military reconnaissance and civilian monitoring.In addition,in some complex application situations including long-time reconnaissance and long-distance rescue,it is difficult for a single FWAV to complete intricate missions due to its low duration and low efficiency.Thus,it is necessary to consider the energy efficient mechanism in formation flight to increase the duration capability in order for the successful accomplishment of the mission.In this paper,the optimal configuration of FWAVs is analyzed inspired by the formation flight mechanism of wild geese,and the theoretical results are verified through CFD(Computational Fluid Dynamics)simulation and wind tunnel experiment.Finally the energy efficient mechanism of FWAVs in formation flight is summarized.Specifically,the following main research works are carried out:(1)The wingtip vortex model and upwash model are established.Then,the relationship between lift and drag and relative distance is obtained by theoretical analysis.Upon this basis,a well-specified configuration of FWAVs with the least energy consumption is formulated,and a configuration switching mechanism is proposed such that the optimization and balance of the whole energy consumption are guaranteed.(2)The reasonable CFD(Computational Fluid Dynamics)simulation and wind tunnel experiment are designed.With the collected data,we analyze the effects of relative phase difference and relative distance between neighboring FWAVs in the efficiency of formation flight.Through meticulous data analysis,the regulations of generation and dissipation of the wingtip vortex are revealed,and an optimal longitudinal distance between two neighboring FWAVs is established.Based on these results,a more specific optimal configuration is obtained,thereby verifying the foregoing theoretical result.(3)Considering the vortex effects,a dynamic model of FWAVs is established,and a distributed controller is designed to form,maintain and switch the optimal configuration.Finally,by combining with the energy consumption model,the energy consumption optimization of the formation configuration and the effectiveness of the controller are verified by a simulation example.This research can provide the reliable theoretical and data support for the efficient mechanism of FWAVs,and further provide a novel research strategy for forming the optimal configuration in formation flight.