Research On UAV Navigation Based On Bionic Algorithm And UAV Array Beamforming

Since the historical record,China has been a country with frequent natural disasters.After natural disasters such as earthquakes and floods,areas are often faced with signal interruption and power interruption caused by the destruction of communication equipment.In order to quickly carry out rescue and disaster relief work,it is necessary to establish an emergency communication system as soon as possible.Unmanned aerial vehicle（UAV）,as a small aircraft,is regarded as the best choice for emergency communication platform due to its strong mobility,versatility and low deployment cost.However,extreme weather usually leads to weak satellite navigation signals in disaster areas,which are vulnerable to interference and cannot work normally.At present,the autonomous navigation of UAVs mostly relies on satellite navigation technology.In order to reduce the dependence of UAV emergency communication platform navigation on satellite signals,it is necessary to study the bionic navigation algorithm.Then,the UAV emergency communication platform needs to complete the task of information transmission,and the antenna is an important medium for information transmission with the outside world.According to the needs of UAV communication system,the antenna should have the characteristics of broadband,low profile,flexible beam coverage and anti-interference.Therefore,the research on broadband,low-profile,circularly polarized antenna array and beamforming technology has very important practical significance and application value for UAV communication system.The main research contents and conclusions of this paper are as follows:1.By studying the biological characteristics and hypothesis model of grid cells in animal brain,and drawing on map composition characteristics of grid cell,a hybrid-scale navigation topology construction method based on grid cells is proposed,and then the bionic navigation algorithm is realized by using the continuous image sequence recognition matching algorithm to identify the nodes of the navigation topology.Finally,the UAV experiments with straight and broken lines are designed to verify the effectiveness of the UAV bionic navigation algorithm.The experiments show that the flight path error of the bionic navigation algorithm using the hybrid-scale navigation topology is smaller,more stable and less time-consuming than that using the single-scale navigation topology.2.A broadband ridged microstrip patch antenna for UAV and ground communication is designed.By using air medium and adding ridge operation to the ground floor of the typical microstrip patch antenna,the bandwidth is expanded.It was reinforced for practical application.|S₁₁| of the antenna is less than-10 dB in 2.16 GHz～4.38 GHz,and the relative bandwidth is 66.8%,and the maximum gain is 7.7 dBi at 2.4 GHz.The antenna is placed under the UAV for integrated simulation analysis.According to the simulation results,the H-plane pattern of the antenna has a small dent in the φ=180° direction,and the gain is reduced by 0.5 dB.The metal parts of the UAV have only a slight impact on the antenna.3.A circularly polarized antenna array composed of four broadband printed dipole antenna units is designed for the communication between UAV clusters.A broadband printed dipole antenna element is designed by adding two L-shaped broken lines on the basis of the traditional printed dipole antenna,and then the antenna element is placed on the four arms of the unmanned aerial vehicle by sequential rotation of 90 degrees to form a circularly polarized antenna array.The circularly polarized array realizes 41.2%of the 10 dB return loss bandwidth,and the 3 dB axial ratio bandwidth reaches 25.1%.At 2.4 GHz,the maximum gain of right-handed circular polarization is 7.6 dBic,the 3 dB beam width reaches70 degrees,and the profile height is 0.016λ.4.The competitive differential evolution algorithm is applied to the beamforming problem of UAV array antenna.The beam of a single UAV circularly polarized array antenna is optimized by the competitive differential evolution algorithm.The simulation results show that the beam direction switching can be realized flexibly by using single UAV antenna array,and the beam coverage ability of UAV antenna array is improved,and the competitive differential evolution algorithm obtains a lower sidelobe compared with the numerical algorithm.On this basis,the anti-interference technology of UAV array antenna,UAV cluster linear array and UAV cluster plane array is studied.The competitive differential evolution algorithm is used to simulate the wide null beamforming of a single UAV array antenna and a distributed array composed of UAV clusters.The simulation results show that the competitive differential evolution algorithm can achieve wide null beamforming in a certain range of interference directions.Compared with the traditional differential evolution algorithm,the competitive differential evolution algorithm gets deeper null depth and faster convergence rate.