Design And Experiment Of Device For Rape Strip Aerial Seeding

Rape is the most widely distributed oil crop with the largest planting area in China,which has high economic and practical value.At present,the planting mode of rape in China is mainly artificial seeding or transplanting,and the level of mechanized seeding is not high.In order to improve the mechanization level of the whole process of rape production in China,based on the XAG P20 type plant protection UAV platform,this paper designs a kind of rape aerial seeding device based on the electric drive centrifugal seeder,which provides a new technical equipment to solve the problem of common ground seeder difficult to enter or low economic benefit scenario.This paper focuses on the design,trial production,test and the effect optimization of seed landing into strips of rape aerial seeding system.According to the basic technical route of "theoretical analysis—scheme formulation—structural design—simulation—trial production test — evaluation optimization",the special centrifugal collective seeding device and seed guiding device for rape aerial seeding are designed.The main contents are as follows:(1)Based on the technical requirements of rape drill planting and the influence of rotor airflow produced by UAV,the overall structure design scheme of UAV aerial seeding device is determined,the structure composition and working principle of the device are described,and the structural parameters of key components such as centrifugal centralized rape precision seeding system and seed guiding device are determined.(2)The structure design and parameter analysis of the precision seed metering system of the centrifugal collection and row rape were carried out.Based on the improved design of the traditional centrifugal metering device,a convex metering tray is proposed.Taking the rapeseed as the center of mass,a two-dimensional rectangular coordinate system is established on the surface of the metering tray.The movement law of the rapeseed on the surface of the metering tray is analyzed,and the key parameters affecting the performance of the metering tray are obtained.According to the working process of seed metering tray,the thickness of seed filling chamber is 5mm,and the diameter of seed inlet is 14 mm.A funnel-shaped seed tank with wide adaptability is designed.Therapeseed falls into the seed chamber sandwiched between the seed metering tray and the seed metering device shell along the outlet of the seed tank by its own gravity.According to the relationship between the UAV's maximum operating flight speed,the UAV's battery power supply time and the speed of the seed metering tray,the volume of the seed tank is finally determined to be 3.5L.This paper analyzes the form of hole plugging,improves the design of the hole by using the method of chamfering the outside of the hole,determines the diameter of the hole is 3.8mm,analyzes the movement track of rapeseed in the seed metering mouth,and determines that the outlet part of the seed metering mouth is designed as a quarter arc elbow.After calculation and analysis,the total torque required for normal operation of seed metering system is 1.7N·m,and the stepping motor model J-5718HB4401 is selected,with the torque of 2.5N·m,which can meet the actual operation requirements.(3)The simulation of UAV rotor flow was carried out by using ANASY-Fluent software.With the help of reverse engineering technology,the 3D solid model of UAV blade can be reconstructed.Simplified the UAV model,established the flow field simulation calculation domain,carried on the grid division,and adopted the standard k-?turbulence model.The simulation results show that there is a rapidly changing airflow disturbance area under each rotor.In the range of 0 ? 1.5m below the rotor plane,the downwash airflow speed is larger,and the downwash airflow of each rotor is less cross,but then gradually converged into one,and there is a horizontal plane Divide speed.With the increase of the distance from the rotor plane,the velocity of each direction in the air flow area decreases gradually.The analysis and research of the air flow simulation results provide a theoretical basis for the parameter design of the seed guide device.(4)The structure design and parameter analysis of seed guiding device are carried out.The overall structure and working principle of seed guiding device are expounded.The main parameters of seed guiding device are analyzed.Considering the confined space under the UAV platform,the overall size of the inner surface of the cover and the outer surface of the trapezoid joint is 360 mm long and 150 mm wide for the lower surface,300 mm long and 100 mm wide for the upper surface,50 mm high for the upper and lower surface,and 8mm×6mm×20mm(outer diameter×inner diameter×height)for the uppersurface of the cover.According to the simulation analysis of rotor flow,three kinds of seed guide tubes(1.5,2.0 and 2.5m)are designed.According to the working process of the traction mechanism,the serial bus intelligent steering gear with the model of LOBOT LX-16 A is selected as the driving device.The tail seed tube is designed,and the basic structure and design parameters of the tail seed tube are determined.Simulation analysis is carried out for the seed performance of the tail seed tube with the aid of EDEM software.When the maximum seed speed is 2m/s,the seed performance of the tail seed tube is good,and there is no blockage in the simulation process,which shows that the design of the seed tube meets the actual requirements.(5)Based on the electric drive centrifugal rape seed metering system,a bench test of seed metering performance was carried out.The test results showed that when the rotating speed of seed metering tray increased gradually in the range of 40-220 RPM,the total displacement increased first and then decreased,and reached the maximum displacement of 179.65g/min at the rotating speed of 190 RPM,which could meet the requirements of UAV's operating speed of 1-5m/s;the coefficient of variation and the total displacement consistency of each row The coefficient of variation of displacement stability first decreased and then increased,distributed in the range of 4.5%-12.6% and 0.7%-6.2%respectively;the rate of seed damage gradually increased,all of which were within1.673%;based on JPS-12 seed metering device visual inspection test platform,the analysis of seed uniformity was carried out,the results showed that the average number of seeds per meter on the seed bed of the test platform was 23.03,and the average coefficient of variation of seed uniformity was 18.28% ?(6)Based on the prototype of the pilot plant,the field test is carried out.The test results show that when the height of the hand-held seed guiding device changes in the range of 1.5-2.5m,the width of the strip is less than 1/4 of the set line spacing,and the strip index has no significant correlation with the height of the hand-held seed guiding device(the significant coefficient of the correlation analysis is 0.0769>0.05).Considering the actual operation,it is necessary to It is suggested that 2m should be selected as the suitable height of the hand-held seed guiding device for the operation risk and convenience of the personnel and the field operation environment.Under this condition,the field test results are as follows: the strip index is 35.0%,the coefficient of variation of sowing uniformity is 19.26%,which meets the technical requirements of rape strip sowing.