Design And Test On Measurement And Control System For A Self-Developed Seeder-Fertilizer Machine

Precision agriculture is an important development direction of modern agriculture.China's agriculture is in the process of transition from traditional agriculture to precision agriculture,and it has achieved some economic and social benefits.Variable fertilization is an important part of precision agriculture.Variable fertilization technology is in the base of full realize of resources and crop groups mutation,using crop growth model and crop nutrition expert system to guide variables fertilization tools to fertilize for each operating unit in the field in a fine and accurate way.So that fertilizer can be reasonable investment,and it can bring good economic and environmental benefits.On the basis of the early work summarized by the task group,the design of the box and sheave structure of the sowing fertilizer machine was improved and then made a set of double fertilizer sowing machine.This paper designed a special monitoring system for the sowing and fertilizing machine.The system dynamically changes the seeding and fertilizer flow by manually entering the target sowing fertilizer amount combined with the machine operating speed,so that the amount of fertilizer can meet the target requirements in every per unit area.The specific research contents and conclusions are as follows:(1)Construction of lower computer control system.Designed the PCB board in the control of Freescale microcontroller and each block is encapsulated as a separate control node.Installing a node for every box,it is responsible for signal acquisition and motor controlling of the node unit.Configure a GPS node to get the current vehicle location and travel speed.Configure a master node to summarize the information of each node and then be responsible for the decision-making,data storage and real-time communication with the host computer to achieve human-computer interaction.(2)CAN bus communication system construction.Combined with the microcontroller comes with CAN module and an external CAN transceiver to build a CAN bus communication system.CAN bus communication protocol is configured by software,so that each node can achieve the transmission and share of information through the CAN bus.(3)Construction of host computer control platform.This paper use the touch screen as a human-computer interactive terminal.The host computer control platform composed of power supply,wireless module and the touch screen.Develop a communication protocol between the upper and lower machines.Design of graphic human-computer interface for touch screen to achieve touch-type man-machine control and fertilizer machine operating status display.(4)Calibration test and performance test of sowing fertilizer.Calibration test:Made the calibration test for the improved outer fluted-wheel.The mathematical model of the variable control between the row of fertilizer(sowing)and the speed of vehicle operation and the amount of fertilization(sowing)per unit area was established.The calibration test showed that the single channel fertilizer(sowing)had a good linearity and the coefficient of variation of the consistency between the channels is 6.02%and the maximum standard deviation was 41.7 g/min.Performance testing:The experiment was carried in the case of setting the target area of the same amount of sow and fertilizer.When the fertilizer machine was working at a non-uniform speed,variable fertilization controller can effectively adjust the wheel speed to maintain the stability of real-time fertilizer per unit area according to the established control model.The maximum relative error of actual seeding and target value is 3.79%.(5)Fertilization seeder field experiment.Aiming at the speed and the target of sowing and fertilizing machine operation in per unit area,two field tests were carried out under the real conditions.Specifically including:Setting the same unit area target sowing fertilizer under the different operation speed.Set different target sowing fertilizer rate per unit area under the same speed.The results showed that the maximum relative error of the actual sowing fertilizer and the target value is 5.58%.The maximum theoretical unit area real-time broadcast volatility is 5.62%and the maximum variance is 6.8%The results showed that the variable sowing and fertilization monitoring system developed in this paper is stable.It has a higher control and detection accuracy than common one,so that it can be able to meet the precision of variable sowing fertilization control requirements.