Numerical Simulation And Experimental Research On The Obstacle Avoidance Spray Of Four-rotor Plant Protection UAV

This article aims at the four-rotor plant protection UAV to avoid obstacles in a circular arc near the obstacles,and uses a combination of numerical simulation and experimental verification to obtain the laws of the rotor wind field and the deposition of spray droplets in the obstacle avoidance state.Through experiments,the uniformity and effective deposition of droplets near the obstacle are optimized,so as to achieve the goal of uniform droplet deposition near the obstacle and reduce respray.The main research contents are as follows:Ⅰ.Research on the rotor wind field of a four-rotor plant protection UAV under obstacle avoidance state(1)In terms of the influence of the obstacle avoidance speed v on the rotor wind field,the wind field as a whole is inclined to the side close to the obstacle.As the obstacle avoidance speed increases,the deviation of the wind field toward the obstacle side becomes more obvious;close to the obstacle The wind speed under the rotor on one side is obviously greater than the wind speed under the rotor on the side far from the obstacle,and the wind speed under the rotor on the side close to the obstacle is the highest.(2)In terms of the impact of the obstacle avoidance height H on the rotor wind field,it can be seen from the wind speed under the front rotor that the wind speed under the rotor far away from the obstacle is slightly higher than the wind speed under the rotor near the obstacle,while the rear rotor is close to the obstacle.The wind speed under the rotor on the object side is significantly greater than the wind speed under the rotor on the side away from the obstacle.Ⅱ.Research on spray droplet deposition under obstacle avoidance state of fourrotor plant protection UAV(1)In terms of the impact of obstacle avoidance height H on the deposition of obstacle avoidance spray droplets.The amount of droplets deposited on the side close to the obstacle is much higher than that on the side far away from the obstacle;as the height of the obstacle avoidance increases,the uniformity of the droplet deposition becomes better,and the effective deposition range shows a tendency to gradually move away from the obstacle.The obstacle avoidance velocity v is the same as the above rules for the deposition of obstacle avoidance spray droplets.(2)In terms of the effect of droplet size VMD on the deposition of obstacle avoidance spray droplets.As the VMD of the droplet size increases,the uniformity of droplet deposition becomes better,and the effective deposition range shows a tendency to gradually move away from obstacles.(3)Obstacle avoidance spray test results are basically consistent with the numerical simulation results and meet the engineering requirements.The calculation results of the numerical calculation model of the four-rotor plant protection UAV obstacle avoidance spray are reliable.Ⅲ.Research on droplet deposition of four-rotor plant protection UAV obstacle avoidance spray(1)Obstacle avoidance height and obstacle avoidance speed have a significant influence on the coefficient of variation of droplet deposition uniformity,and the interaction between the two factors has a significant effect on the coefficient of variation of droplet deposition uniformity.(2)The obstacle avoidance height has a significant influence on the farthest effective deposition distance,and the obstacle avoidance speed has a significant influence on the farthest effective deposition distance.The interaction between the two factors has little effect on the significance of the farthest effective deposition distance.(3)Through the obstacle avoidance spray verification test,the relative error between the predicted value and the test value is within 10%,which can be used to guide the four-rotor plant protection.The man-machine is close to the obstacle and uses the arc path to avoid obstacle spraying.