Research On Electrostatic Spray Technology Of Multi-rotor Plant Protection UAV

Multi-rotor UAV(Unmanned Aerial Vehicle)plant protection technology has been widely used in a variety of complex crop plant protection scenarios.And the operation efficiency has been greatly improved,but the utilization rate of pesticides still need to be improved.For planting with a certain depth,fog droplets were difficult to be adsorbed on hidden parts of plants,which resulting in an unsatisfactory effect of insect and disease prevention.Electrostatic spraying technology makes use of electrostatic effect to adsorb fog drops to the hidden parts of plants,which can effectively improve the adsorption effect of fog drops,increase the deposition rate of fog drops on the front and back of the target.And thus improving the utilization rate of pesticides.Therefore,the combination of UAV plant protection technology and electrostatic spray technology can improve the operation efficiency and application effect.As the deposition effect of spray drops is different under different spray parameters,it is necessary to study the deposition effect of electrostatic spray drops of plant protection UAV under different conditions and explore the optimal theoretical spray parameters.And it was of great significance to achieve zero growth of pesticides in China.In this paper,the research on electrostatic spray technology of multi-rotor plant protection UAV was mainly carried out from the following aspects:(1)Analysis of influencing factors of droplet deposition effectThe influencing factors of droplet deposition were analyzed.The deposition effect of fog droplet mainly includes the deposition density,coverage rate and uniformity of fog droplet,he influencing factors of droplet deposition are mainly divided into spray parameters and plant target characteristics,among which spray parameters mainly include spray pressure,spray hole diameter,charged voltage,etc.and target characteristics include target shape and size,surface structure,surface roughness,etc.Among them,spray parameters are controllable factors.This paper mainly analyzed the theoretical influence of spray parameters on the deposition effect of fog drops,and established the corresponding influence equation for the deposition effect of fog drops.(2)Simulated spray designBased on the theoretical analysis of droplet deposition effect,the equivalent equation of charged effect was established.The effect of charged voltage on the droplet characteristics is equivalent to the comprehensive effect of spray pressure and nozzle diameter on the droplet characteristics.Based on CFD(Computational Fluid Dynamics)technology and combined with computer design and establishment of spray model,the turbulence model in the spray model adopts the standard turbulence model,and particle tracking technology was adopted to consider the influence factors such as droplet gravity and evaporation.The spray height was set according to the actual scene,and the deposition surface was the trap type to realize the collection of fog drops.The spray model design established a simulation environment for subsequent spray simulation experiments.(3)Design of the platform for testing the deposition effect of fog dropsThe platform for measuring the deposition effect of fog drops was designed.The testing platform for droplet deposition effect mainly included the testing platform for droplet load to mass ratio,the testing platform for droplet particle size and droplet deposition density,and the platform for electrostatic spray system.The load-mass ratio test platform was a software and hardware platform designed based on the principle of mesh target test.The number of mesh layers was 3,and the number of mesh from the upper layer to the lower layer is 400,250 and 100 respectively.The testing platform for droplet particle size and droplet deposition density was a self-designed software platform,which mainly dealt with binary processing,droplet calibration,adhesion droplet separation,droplet count and other processing of droplet images.The spray model design platform was ANSYS software platform.The principle flow of spray model design using the software was introduced.Finally,the electrostatic spray system of plant protection UAV based on the principle of inductive charge was introduced.The system design included device selection,system construction and so on.(4)Droplet characteristic testThe droplet deposition effect under different spray parameters was studied by experiments.By designing the test scheme,the experimental data of droplet deposition effect were obtained and the influences of different parameters on droplet characteristics were analyzed.At the same time,the characteristics of droplet deposition distribution under different conditions and parameters were studied by simulating electrostatic spray test,and the prediction equation of droplet deposition distribution was established.Then an actual spray test was carried out to verify the error between the theoretical model and the actual droplet deposition distribution.Finally,indoor static electrostatic spray test and outdoor dynamic electrostatic spray test were carried out respectively,in order to verify that the electrostatic spray system can be effectively applied to the actual operation scenarios.