| Agriculture in China is altering from traditional rough pattern to precision method.Precision agriculture is a new combination of information technology,biological technology and agricultural produce,the popularization and application of which is the base of realizing efficient agriculture.The variable technology is an important method of precision agriculture,which has a profound and lasting strategic meaning;it will not only reduce environment pollution,increase the quality and quantity,but also consume less fertilizer and reduce the investment.Since 1990s,precision agriculture has rapidly developed and basically formed in Europe and America.Precision agriculture involves fertilization,precision sowing,tillage and watering.A lot of precision machines and applications have been invented with the advanced technology such as GPS,RS,and GIS.However,the investment is great and the soil quality influences a lot.Recently,China has progressed in variable fertilization particularly in the area of variable fertilizer recipe,variable algorithm and the fertilization controller designing.The current problem is that the operation according to the requirement is still not reached;the accuracy is low and the operation is complex,which is hard to apply practically and hard to prompt in the country.Considering the accuracy of the existing fertilizing and seeding machine is low and combining two practical problems of most concern in basic work:automatic adjustment of target amount in fertilization or seeding and uniform fertilization(seeding),my thesis builds a control system of variable rate fertilizing or seeding applicator,it realizes the allocation of wheat,urea and compound fertilizer on demand,intelligent settings of operation parameter,dynamic display and storage.In order to promote the variable rate fertilization,I tried to simplify the technological process,considering the facts that land was allocated to individual households and each plot is small and soil fertility is relatively homogeneous and different plots need significant different care.This paper also built an electronic prescription mapping system based on per yield potential and target yield.The system uses natural plot as a unit,it has realized the function of adjustment of amount in fertilization or seeding between different units and homogeneous fertilizing or seeding within the same plot.Specific research is as follows:(1)The optimal design of traditional fertilization application:combining the concept of "a machine,complex job" in agricultural machinery manufacture,this paper has modified the fertilizer application of the 2BFG-14(8)A produced by Danyang Liangyou Machinery Company.On the basis of retaining the mechanical functions of fertilizing,seeding,rotary tillage,leveling pressing and ditching,this paper focused on improving the drive mode of the fertilizer tank.The work included that fertilizer box transformed from a seed box and a fertilizer box to two fertilizer box and a seeds box in order to fertilize or sow on demand.Fertilization or sowing driven approach from the original mechanical chain transmission to the stepper motor drive,to realize automatic adjustment of sowing or fertilizing amount on demand.(2)The construction of the control system of variable rate fertilization:Control system is the core of variable rate fertilizing and sowing machine.It realizes the function of collecting signal,controlling fertilization,storing and showing the information in work.The system is composed of GPS as the measuring speed node,main control node,fertilizing or sowing executing node,man-machine interaction.The system can communicate with each node rapidly and stably by using software to set the communication protocol of CAN.This paper packaged main model in ECU with CAN port in order to construct a distributed system.(3)The technical measures to improve seeding rate accuracy of variable rate fertilization application:To solve the data fluctuation and weak anti-interference ability of low-cost general accuracy GPS module,a low-cost GPS speed-measurement location system based on Kalman filtering and position difference has been designed independently;In order to solve the inaccurate seeding rate which is caused by the large seeding rate deviation between actual field work and static standard quantification of outer sheave fertilization seeder,existing structure of outer sheave fertilization seeder has been improved.(4)Fertilization seeding experimental test has been carried out in this paper and its results show:The maximum deviation between cumulative actual field fertilization seeding amount and target amount is less by 5%,the dynamic fluctuation of fertilization seeding amount in actual unit area is also less 5%.The results also show:The improved outer sheave fertilization seeder is able to reduce the deviation effectively between actual field work and static standard quantitation.(5)The variable fertilization electronic prescription mapping software system based on productivity potential and target has been perfected in this paper,and following research objective is to give the intent fertilization amount correctly which relies on productivity potential and target of plot and combined with embedded fertilization strategy.This objective is helpful in achieving variable fertilization in natural plots as processing unit and gaining experience of spreading variable fertilization in small southern rural plot. |
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