Design And Research Of Variable Rate Fertilization System For Intelligent Rice And Wheat Seeder

Precision fertilization is the key link in pricision agriculture.The traditional way of fertilization is to use large amounts of fertilizer of the same type and dosage in the planting area,such a practice will not only cause a lot of waste,but also cause a series of environmental pollution problems.Different regions of the fertilizer situation is different,different crops need different nutrients in the growth process.Therefore,variable rate fertilization should be adopted according to the actual situation.According to the condition of soil fertility and crop growth in small area,the technology of variable fertilization applies appropriate amount of fertilizer,thus reducing the amount of fertilizer,saving resources and protecting the environment.At present,there are many problems in variable rate fertilization system of rice and wheat seeder at home and abroad,for example,low intelligence,poor reliability and compatibility of communication system,and lack of monitoring system for fertilization status and so on.Based on the above problems,the variable fertilization system of intelligent rice wheat planter is studied in this paper.Intelligent rice and wheat seeder variable fertilization system uses CAN bus to realize real-time communication between control nodes,and uses GPS positioning system to get farm machinery location in the field.According to the prescription of fertilizer,the amount of fertilizer applied to the machine site is obtained,and variable adjustment is realized by adjusting the opening of the outer slot wheel fertilizer device by step motor.The main research work and innovations of this study are as follows:(1)Design variable fertilizer application device.The device is mainly designed on the basis of the transmission mechanism,the connecting mechanism of the screw and the fertilizer shaft and the spline,and the step motor is used as the power to adjust the axial position of the fertilizer shaft without affecting the rotation of the fertilizer shaft,and then change the opening degree of the outer grooves,so as to realize the variable quantity adjustment.(2)The research and design of the application of fertilizer status detection system.The system takes the thin film pressure sensor as the core detection module,and uses the weak pressure signal produced by the impact sensor of the fertilizer particle drop in the fertilizer tube as the detection object.The signal is processed and identified by the wavelet packet transform and BP neural network technology,and the abnormal state of the clogging of the guide tube or the use of the fertilizer is detected and warn the operator.(3)The model of variable rate fertilization was established.In order to make the variable fertilization control system get the detailed information of fertilizer application,through the experimental calibration,the function relationship between the amount of single circle discharge of the external grooves and the opening degree of the outer grooves and the rotational speed of the outer grooves was studied,and the mathematical model of the total fertilizer amount was established.(4)The design of the control node of the lower computer.Taking the STC89C52 RC as the control core and using the CAN bus as the communication mode,the control node of the speed detection node,the opening detection node,the step motor node and so on is designed.Through the coordinated operation of each node,the fertilization variable regulation and fertilization status information collection were realized.(5)Development of variable rate fertilizer control software.In order to improve the intelligence and automation of variable rate fertilization,variable rate fertilization control software based on Windows platform was designed and developed.The software mainly provides database operation service,human-machine interaction interface and fast and efficient data calculation.Through the CAN bus communication,the data of the node feedback of the lower computer is collected in real time,and the decision information of fertilization is analyzed and calculated in combination with the data of the database,and then the variable control of the step motor node is controlled.(6)In order to verify the performance of variable rate fertilization system designed by intelligent rice and wheat planter,static and field experiments were carried out.The test results show that the communication between the nodes of the system is stable and reliable,the abnormal state of the fertilizer is detected accurately,the abnormal state recognition rate reaches 95.3%,and the alarm is timely.The regulating mechanism of variable rate fertilizer machine responds quickly and accurately.The design of the whole machine is reasonable,the system works stably,the precision of variable rate fertilization reaches over 93%,and all the technical indexes meet the requirements of agronomy,at present,it has been checked by the expert group.The research in this paper provides technical and data support for the design and production of intelligent rice and wheat variable rate fertilizer applicator in China.