Control Of Greenhouse Environmental Parameters Based On Model

With the development of the society, facility agriculture has been paid more andmore attention. The greenhouse is the key in facility agriculture. Greenhouse is halfclosed system, will be affected by the external environment change at any time in thegreenhouse. Factors affecting greenhouse outside are: air temperature, air humidity, airintake, solar radiation. Factors affecting greenhouse inside are: heating device, soilradiating, crop transpiration cooling. In the control object, the two most important factorsin the greenhouse are temperature and humidity. Greenhouse temperature and humidityhave the characteristics of nonlinear, coupling and so. According to these characteristics,this thesis studies a kind of intelligent control algorithm of fuzzy dynamic model basedon PID.This thesis firstly analyses the change process of greenhouse environmenttemperature and humidity, set up a dynamic mechanism model of greenhouse. Bysimplifying the greenhouse model is approximated as a first-order plus dead time process.Using fuzzy-PID control to control greenhouse temperature and humidity. Then it putsforward a solution according to the characteristics of strong coupling betweentemperature and humidity model, which is based on the humidity (temperature) tochanges in temperature (humidity) influence, the humidity (temperature) changes intotemperature (humidity) variation, feedback to the temperature (humidity) input control,so that the temperature (humidity) as the input into the controller again in a certaincompensation, to control the next cycle.Finally using MATLAB software simulation tested the system controller. The resultsshow that, the control algorithm of this thesis solve the strong coupling betweentemperature and humidity, and the control stability the temperature and humidity ingreenhouse. With a small overshoot, fast convergence speed etc..To meet the greenhousenonlinear, large time delay, multi input, multi output complex control systemrequirements.Finally, the thesis summarizes the research contents, and the next research in detail...