| In the process of rice growth,the rational and effective application of fertilizers is an important measure to improve the high quality and high yield of rice and increase the income of rice.At present,China's rice fertilization operation is basically based on the experience of uniform fertilization.The backward fertilization method not only results in over-application of fertilizer,but also reduces fertilizer use efficiency.Fertilizers that have not been absorbed and utilized by crops will also lead to a series of ecological and environmental problems such as eutrophication,soil compaction,and acidification.Therefore,in rice production,it is necessary to study scientific and reasonable fertilization techniques to achieve the effects of fertilizer saving,production increase,and environmental protection.Variable fertilization technology,as an important part of modern precision agriculture,refers to a precise operation technology that completes on-demand fertilization operations on the premise of fully understanding field fertility,crop and environmental information.The existing researches on rice variable fertilizer applicators are mostly concentrated on solid fertilizers,and most of them use external wheeled row fertilizers to perform row fertilizers.However,the viscosity of domestically produced solid fertilizers becomes large after they have become wet,which can easily block the machine tools,causing uneven distribution of fertilizers and the inability to discharge fertilizers,thereby affecting crop growth.Compared with solid fertilizer,liquid fertilizer has the advantages of high absorption and utilization,good fertilizer efficiency,precise distribution ratio,and easy mechanical application.At present,the domestic liquid fertilizer application technology mainly uses electro-hydraulic proportional valves to control the flow,which has the problems of high cost and slow control speed.Moreover,the control of micro flow rate has not been well resolved.Therefore,in order to solve the problem that the electro-hydraulic proportional valve is difficult to achieve fine adjustment of minute flow rate,an electromechanical flow control valve is designed and a fuzzy PID adaptive controlalgorithm is used to develop a low-cost liquid fertilizer spreader variable adjustment system.Precise adjustment of the flow rate of the tiny liquid fertilizer,and experimental verification of the working performance of the variable control system for the liquid fertilizer applicator.The main research contents and conclusions of this article are as follows:(1)According to the fertilization agronomic requirements of rice field management,combined with the design goals of the liquid fertilizer variable regulation system,a variable fertilizer application platform for liquid fertilizer was established.Based on the design requirements of the liquid fertilizer fertilizer variable adjustment system,the liquid fertilizer fertilizer variable adjustment system was implemented.Overall design.Through the construction of the fertilizer supply unit,variable fertilizer application control unit,variable fertilizer application unit,and fertilization unit,the construction of a variable fertilizer application platform for liquid fertilizer is completed.Based on the variable-rate fertilization control unit and variable-rate fertilization detection unit,a variable regulation system for liquid fertilizer applicator was developed and a fuzzy PID adaptive control algorithm was adopted.Through the adjustment of the opening degree of the electromechanical flow control valve,the on-line adjustment of the amount of fertilizer was realized,and the variable was applied to the liquid.Fertilizer provides platform support.(2)Based on the flow control valve and gear design and the selection of electromechanical steering gear,an electromechanical flow control valve was developed.The hardware circuit of the variable regulation system for the liquid fertilizer applicator was built with the single-chip microcomputer as the control core.The hardware adjustment system for the liquid fertilizer applicator variable regulation system was designed.In order to realize variable-rate fertilization of pneumatic ejector,a flow control valve was designed according to the fertilizer application amount,and the EMS was selected through the flow control valve start-up torque and control speed requirements,and the gear size was determined.The overall structure of the electromechanical flow control valve was designed.Through the electromechanical flow regulating valve fertilizer calibration experiment,the relationship between the angle of the rudder actuator and the average mass flow rate of the liquid fertilizer was obtained,and the flow adjustable range was determinedto be 2.36-6.75g/s.Using STC89C52 microcontroller as the control core,complete the connection between the microcontroller processing module and the variable control module,the detection module,the liquid crystal display module,the keyboard input module,and the alarm indication module to form a hardware circuit.The variable control module includes the electromechanical flow control valve and the solenoid valve.Provides parameters and hardware foundation for the software design of the variable regulator system for liquid fertilizer applicators.(3)Based on the design goals,requirements and hardware basis of the variable regulation system for liquid fertilizer applicator,a fuzzy PID adaptive control algorithm was used to perform simulation analysis,and the software for the variable regulation system of the liquid fertilizer applicator was designed.According to the agronomic requirements of rice fertilization and the field operation speed of the implement,the target mass flow rate of the fertiliser is determined,and the main program of the single-chip processor,the variable control subroutine,the signal detection subroutine,the liquid crystal display subroutine,the keyboard input subroutine and the alarm indicator are determined.The program was designed.The adaptive PID control algorithm based on fuzzy PID is studied.By analyzing the model of opening and closing adjustment system of electromechanical flow control valve,the transfer function of the opening regulation system is determined.A fuzzy PID controller is designed and a critical proportionality method is used to determine three PID controllers.The initial value of the parameter.The difference between the fuzzy PID control and the conventional PID control is analyzed through the Simulink platform in MATLAB.It is concluded that the fuzzy PID control has good control performance,can better adapt to the change of the controlled object,and the overall performance is better than the PID control and can be better.The realization of precision variable fertilization control.(4)Test of a liquid fertilizer applicator variable regulation system.In order to analyze the control performance of the variable control system of the liquid fertilizer applicator,a test platform based on the tractor in the well field was set up to test the performance of the variable control system for the liquid fertilizer applicator.Based on the variable fertilizer application platform for liquid fertilizers,a test platform based on a tractor in the well field was set up.The performance test of control accuracy and the tracking performance of fertilizer application were conducted.The results of control accuracy verification test show that the average control error of the variable-rate fertilization control system is 4.53%,and the control accuracy can reach over 90%.The verification results of the fertilization amount follow-up performance test result show that the overshoot of the system response is less than 16.6% and the rise time is less than 2.7s.At steady state,the flow rate of fertilizers fluctuates to a less extent,which can meet the requirements of precision agriculture variable fertilizer application. |
PDF Full Text Request