| Most of the pesticide mixing methods in the current plant protection spray process in China are pre-mixed.This method of mixing pesticide will lead to large proportioning errors,more waste of pesticides,and harm to personal safety.In this paper,an online pesticide mixing system based on plant protection machine is designed to separate the pesticide box and water tank to achieve the separation of pesticide and water,which can reduce the harm of pesticides to the health of the operator and ensure the safety of the operator;the ratio of the pesticide and water can be adjusted according to the actual needs of the operation to achieve precise dispensing Ratio,reduce the pesticide residues of agricultural products,improve the quality and added value of agricultural products;improve the uniformity of pesticide mixing,improve the utilization rate of pesticides,increase the yield of crops;meet the requirements of precision agriculture for precise dispensing and application.The main research contents of this article are as follows:(1)On the basis of consulting a large number of documents,this paper designs a set of online pesticide mixing system for the problems of the current pesticide mixing method and the shortcomings of the existing pesticide mixing device.This system mainly includes a water intake unit,a pesticide intake unit,a control unit,and a spraying unit,which solves the problem that it is difficult to ensure the performance of the pesticide mixing when the pesticide is mixed with a large coefficient and the water flow is adjusted in a large range.(2)Based on the STM32F103R8T6 development board,an online pesticide mixing control system was designed;a peristaltic pump was used to design an accurate pesticide taking unit for the problem of small flow precise pesticide taking in the online pesticide mixing system;a closed-loop control system was designed to precisely regulate the water taking amount for water taking amount control;The control system is designed to meet the needs of precise regulation of the water intake pump and the pesticide intake pump according to the actual operating conditions.(3)Design a built-in spoiler mixer to improve the mixing performance of the mixing system.Design the main structure of the mixer and the internal mixing unit,and analyze the angle of the injection port,the height,number,angle,and position of the spoiler that affect the mixing performance of the mixer,and determine the angle of the injection port and the spoiler angle And the range of the height;the orthogonal test method is used to experiment the angle of the injection port,the spoiler angle and the height,and the optimization model of the mixer is determined by intuitive analysis and analysis of variance.(4)According to the system design,build an on-line mixing system atmospheric pressure mixing and pressurized mixing test platform,and carry out the system stability test under pesticide pressure and normal pressure on the test bench.The ultraviolet spray spectrophotometric method was used to detect the spraying liquid of the system to determine the concentration of the mixed liquid.The test showed that the absolute error and relative error of the mixed concentration of the pesticide and water were improved when the pressure was1 MPa,and the maximum relative error was 3.31%.Good stability.(5)On the pressurized pesticide mixing test platform,the image analysis method based on high-speed photography is used to qualitatively analyze the pesticide mixing performance of the pesticide real-time mixing system,proving that the system has good pesticide mixing performance.On the test platform of normal-pressure mixed pesticide and pressurized mixed pesticide,the ratio of mixed pesticide was changed to carry out the uniformity test of the mixed pesticide.The test showed that: when the mixing ratio of the pesticide is 1: 300 ～ 1: 3000,when the pesticide is mixed under normal pressure,the mixture is uniform The overall trend of the coefficient of sexual variation increases with the mixing ratio;when pressurized and mixed,the coefficient of variation of the mixing uniformity is less than 5%,and the maximum is 3.903%.This shows that when pressurized and mixed,the online mixing system mixes Uniform performance is good.The test results are compared with the CFD simulation results to prove that the CFD model is true and reliable.(6)On the pressurized drug mixing test platform,conduct variable-pressure test of the water intake pump within the range of 1: 300 ～ 1: 3000 to determine the uniformity of drug mixing in the system.Adjust the water intake to change within the range of 40 L / min ～ 140L/ min.The mixing uniformity coefficient of the online mixing system decreases with increasing water flow.The mixing uniformity coefficient of the online mixing system is less than 5%.It still applies when the water flow changes. |
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