Design And Experiment Of Variable Spraying And Boom Balance System Of Self-propelled Boom Spraying Machine

With the development of agricultural science and technology,the spray bar spraying machines,which are the main working machines in the field plant protection sector,are bound to develop in an intelligent and large-scale way.In order to prevent economic losses and environmental damage caused by the extensive use of chemical pesticides during plant protection operations,it is particularly important to upgrade the intelligence of the main working parts of the spray bar.Therefore,in response to the problem that most of the existing domestic field spraying machines do not have active balancing functions and use quantitative spraying methods,and with the goal of improving the intelligence of domestic spraying machines,a spray bar balancing system and a variable spraying system were designed on the basis of the existing spraying machines in the subject group,with the following specific research content.(1)The overall control scheme design of the spraying machine.The key components and parameters of the existing spraying machine were analysed,the advantages and disadvantages of hydraulic control and servo-electric cylinder control were compared,and the servo-electric cylinder-based spray bar balancing control scheme was selected.For the variable spraying system flow control problem,compared the advantages and disadvantages of variable pump control and proportional valve control,selected the "diaphragm pump+proportional solenoid valve" circuit throttling control scheme.(2)Design of key components of the spray bar balancing system.For the ultrasonic distance sensor in the spray bar active balance process due to ground bumps resulting in the measurement of crop canopy spacing accuracy was low,the detection information of the angle sensor was used as the basis for the balance of the boom.The welding rod was modified to propose a wrong-plane servo-electric cylinder balancing method.The modeling analysis of the whole spraying machine was carried out,and the transfer function of the spraying machine deflected by ground excitation was established.The relationship between the initial deflection angle of the body and the change of the angle of the spraying bar on both sides and the maximum displacement of the end was investigated and used for the prediction of the spraying bar balancing.For the dynamic characteristics of the spray bar balance system,a fuzzy PID control method is used and simulations are carried out to verify the feasibility of the scheme.(3)Design of key components of the variable spraying system.In response to the problem of Hall speed distortion when the spraying machine was operating at high speed and inaccurate speed measurement by Beidou or Doppler radar at low speed,a dual speed measurement mode based on Hall speed measurement and Beidou navigation speed measurement was adopted to adapt to different driving speeds.The relationship between wheel slip rate and speed of the spraying machine was studied and analysed,and the switching conditions for the transmission of the speed measurement values were determined,so that the Bei Dou speed measurement values were selected as the basis for the system flow calculation when the spraying machine was operating at high speed.The components of the variable spraying system were selected,the step-down circuit of the system and each sensor detection circuit were designed,and the mathematical model of each sensor detection value was established and calculated.The fuzzy PI control method was used as the control strategy for the variable spraying system and simulations were carried out to verify the feasibility of the scheme.(4)System development and test analysis.A spray bar active balancing system based on servo-electric cylinder regulation was built on the existing spraying machine,while a variable spraying system with dual speed measurement mode and loop flow regulation was added.The test investigated the effect on the spray bar oscillation before and after the addition of the spray bar active balancing control section at a driving speed of 7.2km/h under the same road conditions in the test field.The spray bar deflection angle was reduced by a maximum of 2.54° and the end displacement was reduced by a maximum of 216 mm with the addition of the spray bar active balancing device.Variable spraying tests were carried out in the field at speeds of 6,7 and 8 km/h and variable speed variable spraying tests at speeds of 5 to9 km/h,with an overall error of less than 3%,in line with the needs of the spraying operation.