| Traditional seeders land wheels tend to slip,which is likely to affect the fertilization effect,and the operation mode is not flexible,domestic fertilization is mainly controlled by single-quality fertilizer or compound fertilizer,which can't realize automatic matching of multiple fertilizers as well as accurate fertilization.In order to solve the problems above,the thesis refers to the research status of fertilization at home and abroad,puts forward the research and experiment on automatic matching fertilization control system of electric seeders,The research content is as follows:(1)Study and analyze the 3 common fertilization control plan,mechanism characteristics of fertilizer apparatus and major factors influencing quantitative change of fertilization,designe the closed-loop variable control plan based on motor speed regulation.Calculate the rotating apparatus of the fertilizer apparatus,and work out the relation between the required speed of the fertilizer and the fertilizing amount within the unit time.Analyze principle of PID algorithm,calculated amount and accuracy;combined with the system's operational capability,add incremental PID to the motor speed closed-loop adjustment of the system.(2)Study requirements and functions of the upper computer,define the module function of the upper computer and complete the design and development of the upper computer.Confirm the hardware selection,interface setting and formulation of communication protocol of the upper computer,including address allocation,the upper computer's control instruction protocol format to the lower computer,the lower computer's data order format to the upper computer,zone bit of normal and abnormal data,and ways of instruction issue.(3)Complete the hardware design and programming of the lower computer's fertilizer controller.The STC15W4K32S4 MCU is confirmed to be the core processor of the lower computer.Respectively design the wireless communication module circuit,power circuit,fertilizer's rotating speed measuring circuit,motor drive circuit as well as acquisition circuit of the locomotive speed.Design the fertilizer tank into a three-tank one as a whole,realizing the matching and fertilizing of nitrogen,phosphorus and potassium.Complete the watchdog allocation of the fertilizer controller in the lower computer,serial port communication as well asdesign of motor drive programming;add PID algorithm into the speed control program of the motor speed,so as to improve the response characteristics and control accuracy of the system.(4)Carry out static calibration test and field dynamic test.As for the static calibration test,it makes equation fitting based on the acquired data by adjusting PWM proportion to control the fertilizer apparatus' s rotating speed.In this way,confirm the equation relation between the duty ratio and the fertilizer apparatus' s rotating speed,which is found within a long period of effective working time,the operating characteristics of the fertilizer has good consistency and stability.In the field dynamic test,by calculating and analyzing the test data,it shows the system's control error of straight fertilizer is less than 9%,and the consistency variable coefficient of the fertilizer sowing amount in each line is less than 13%,and the stability variable coefficient of the overall fertilizer sowing amount is less than 7.8%,which is superior to national fertilizer machinery standards.(5)The system operation mode is flexible and easy to use,it achieves accurate fertilization.The system realizies the matching and fertilizing of nitrogen,phosphorus and potassium according to the input recipe information,Minus the artificial complicated labor,reduces the cost of agricultural production,improves the fertilizer utilization ratio and reduces the ecological environment pollution.The system possess good social benefit,economic benefit and ecological benefit. |
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