Research On Uav Side Spray Device And Flow Detection

Plant protection unmanned aerial vehicle(UAV)will encounter obstacles when performing field spray operations.The UAV needs to achieve effective spray coverage of crops around obstacles while avoiding obstacles,to minimize re-spray and miss-spray.This paper designed a side spray device that realizes the side spray technology of plant protection UAV.The experiment is carried out with the range,deposition range,uniformity and particle size as evaluation indicators.In addition,this article explores the relationship between the nozzle acoustic signal and the flow rate under working conditions,and conducts experimental research under laboratory conditions.The main contents of this article are as follows:1)Design of plant protection UAV side spray deviceAccording to the characteristics of spray leakage in the obstacle avoidance area of the plant protection UAV,a side spray device is designed,which can realize the spraying operation of crops in the obstacle avoidance area,and the spray performance meets the spray requirements.A side spray mechanism is designed to be conveniently installed on the plant protection UAV to provide support for the spray system;a programmable swing mechanism is designed to increase the lateral spray delivery capability of the droplets.2)Verification test of plant protection UAV side spray deviceIn laboratory tests and field tests were carried out to verify the performance of the side spray device,with the range,droplet deposition coverage and particle size distribution characteristics as evaluation parameters.It can be known from the laboratory test results that the particle size spectrum of the device under two pressures meets the particle size requirements of aviation spray.When the spray pressure is 0.3 MPa,the median diameter of the droplet volume is 198.879 μm,and when the spray pressure is 0.4 MPa,the median diameter of the droplet volume is 103.415 μm.When the spray height of the device is 1.5m and the spray pressure is 0.4MPa,the spray distribution effect is the best.Within the range of 0.65 ～ 1.45 m,the spray volume is more than 20 mL/min,the spray volume is sufficient,and the spray volume difference is up to 0.13 mL/s.The spray is evenly distributed.Finally,a field test was conducted to verify the operation effect of the side spray device.The results show that the smaller the angle between the spray surface and the horizontal plane,the more beneficial it is to increase the spray deposition coverage of the side spray area.When the included angle is 0° and 45°,the deposition range formed in the side spray area is larger,the straight-line distance is greater than 2m,and the coverage of fog droplet deposition range is24.79% ～ 32.08%.It is proved that the side spray device can realize the effective spraying operation of the side spray area.3)Flow estimation based on acoustic methodUnder laboratory conditions,the optimal spatial position of the nozzle and the sound pressure sensor array and the relationship between the nozzle acoustic signal and the flow rate were studied.Taking the horizontal distance between the sound pressure sensor array and the nozzle as the test factor,the optimal measurement position is analyzed.The results show that the nozzle is located 6cm directly in front of the center of the disc array,and the noise data obtained is determined to be the best position with the least noise.After that,through the curve fitting toolbox,a normalized fitting curve of power energy and nozzle flow rate was established.The Sum of Square Error(SSE)was 0.865 and the standard deviation Root Mean Square Error(RMSE)was 0.93.These results demonstrate the feasibility of accurately estimating the nozzle flow rate based on acoustic signals.