| The study and development of the technology of Precision Agriculture(PA) isderived by recognition of difference from crop's growth environment and yield inthe cause of agricultural cultivation, whose core is precision positioning andvariable rate application supported by GPS, GIS and RS, etc. The fertilizer is mainelements of agricultural high yield and increase production, and the cost of fertilizertakes greater parts among total cost. The input and the utilization ratio of fertilizereffects agricultural output, peasant's income and environmental quality directly.Variable Rate Fertilization (VRF) is suitable for different needs for areas, crops,soils and crops growth environment. With balance applying fertilizer, VRF canimprove the fertilizer utilization ratio, and has obvious economic and environmentalbenefits. Inputting fertilizer has some problems in our country, such as unreasonablestructure, low average utilization ratio of fertilizer, failing to give full play offertilizer in increasing production benefit. In researching of VRF, it is main work tointroduce foreign advanced equipments to track, digest and absorb. So, it isnecessary to study and to develop the technology of VRF according to our nationalconditions, which has important theoretical meaning and practical value to realizeagricultural sustainable developments. The paper is supported by the subject of "Study on technology of automaticVRF in PA" founded by Jilin Province development of science and technology andthe project of "Technology of VRF in PA" supported by Jilin Province agriculturedevelopment general office. This paper introduces the design of automatic controlsystem of 2BFJ - 6 variable rate fertilizer applicator and the simulation of field gridsIVAbstractdiscern etc. The main work and results are as followed:(1) Control project and model of automatic VRF are established. To the existing working condition of countryside in our country, and fully considering the reliability that agricultural machinery needs, manual and automatic methods of control are adopted in the automatic control systems of VRF. On the base of analyzing the main elements that effect fertilizer and the rule of control fertilization, the control model of step motor's rotary speed in automatic VRF is confirmed. It sets up theoretical foundation for automatic controls of VRF.(2) SCM control system is developed as controller of automatic VRF executive body. According to the requests of control system, the input and output of system and the communication are analyzed, and the structure of control system is designed. The hardware electric circuit of SCM control system is confirmed, which includes receiving DGPS signals, receiving sensor signal of tractor velocity, keyboard inputting, IC card interface, pulse output of step motor, displaying screen and warning etc. Verified by the experiment, the control system is relatively steady, reliable, and meets the request of using.(3) Design program of control system. The program is written by using high-level language tool C51 that used in SCM development. It can realize VRF by means of manual and automatic control. In automatic method of control, program has finished receiving positional and velocity information from GPS receiver working in mode of DGPS. It can discern the field grids accurately and search quality of fertilizer per hectare correctly, and then it outputs the pulse to drive step motor and completes VRF. In manual method of control, program can receive and deal with sensor pulse signal and keyboard characters. Then it outputs the pulse to drive step motor and completes VRF. At the same time program solves these problems such as the communication between control system and computer, displaying the results, continuous start of step motor, and so on. In addition, program has many properties such as high-efficient, simple and c...
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