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In recent years, the agriculture stanza water technique develops quickly, the development trend already from lose water in the field to transfer living creature stanza water, farm crop quantity the control use science management, but at precise irrigation and irrigation system of automatic aspect, our country between leading a horizontal margin still more far, placed in separately of experiment research stage.Passed by to our country the market analysis present of fatty device, this text research at the foundation of the irrigation,surround PID control technique, put forward two kinds of projects: programmable controller system and single slice machine system.Combine from the convenience, maintenance of development period and so much etc. aspect consider, we develop the PLC control system device.This text discussed the soft and hardware design, how to choose a type, finally explaining the resolve method which we met in the problem .Aim at the shortage that PLC control system price high,we put forward a single slice machine control project, carrying a project which design according to the single slice of AT89S52.The adjusting of liquid density(EC ) is the point of this equips,we carried on an opening wreath rank experiment of a jump to try, analys the system is inertial, not line, large empress.Adopt numerical PID test to the system, result the accuracy is high, but it have depravation when the liquid density change more.From adoption of opening a wreath rank an experiment of a jump , simplify to enlarge critical comparison method and misty control, in the foundation of normal PID, lead to experience, make control system not to be depended on the system mathematics model, so it has stronger stick and anti-interference ability.The experiment expresses the accuracy high, can adapt a liquid density variety. Control performance in the steady 3 minute such as time, precision 0.15ms/cm, exceed the transferring <15%. Because acid (alkali) liquid is single, adopt steps jump and ordinary PID, it can remedy system delay time ,it makes a good effection, the experiment shows steady time about 3 minutes, precision 0.15PH, exceed the adjusting <15%. This automation fertilizer device, equipment performance up to the require of industry commercialize.
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