Key Technology Study On The Variable-rate Fertilizer Control System Based On Prescription

The development of variable rate fertilizer applicator is significantly improved the utilization of chemical fertilizer. Through implementation of variable fertilization according to different status, the variable method could reduce the problems of environmental pollution, which also has the positive economic benefits for agricultural production cost. Therefore, the variable-rate fertilization technology becomes the focus research field of farm machinery and equipment all over the world. This study expects to improve the utilization rate for the purpose of liquid fertilizer system; according to research status and trend of variable fertilization system development at home and abroad, by the way of combining theory with practice.This study separates the system into four parts. They are terminal control unit from upper computer, communication modules, fertilization controller from slave computer and fertilizer apparatus. The key research contents are as follows:(1) The terminal control unit is the basis of this study, which consists of location information collection, information inquiry from prescription, calculation of fertilizing amount, amendment of position lag. Develop the control software based on flushbonading Win CE.(2) The communication modules is the hinge of this system. Serial RS-232 communicates with terminal control unit. MAX485 communicates with fertilization controller from slave computer.(3) The fertilization controller from slave computer is the main content of this study, which consists of receipting the control signal, driving the circuit, calculation of feedback. Research and develop the fertilization controller based on SMC.(4) The variable-rate fertilizer applicator is the actuator of the system, which consists of diesel engine, fertilization pump, electric regulating valve, pressure transmitter and flow meter. Research and develop variable-rate fertilizer applicator based on the tractor as carrier.(5) Then a simulation of the system working process is conducted with the help of the Simulink module of MATLAB, and the dynamical and static performances of the system are analyzed. It is indicated that the control system meets the demands of variable-rate liquid fertilizing system.(6) According to the development of variable liquid fertilizer technology at home and abroad, through the scheme comparison research, chose the hydraulic system, electric variable pressure valve to implement the variable control. The hydraulic system is used for field trials and electric variable pressure valve is used for bench test. Design the control system’s hardware, software, performance and test optimization, the system achieved the purpose of adjusting the fertilizing amount according to the given fertilizer signals automatically.