A Study On The Intelligent Control System Of Greenhouse Irrigation Based On PLC

The deficiency of water resource is one of great challenges faced by the world today, which has attracted world wild attention. Agricultural production is the first major water users, water deficiency highlights the importance of water-saving agriculture. As an important part of agricultural production, greenhouse plays a more and more important role in agricultural water-saving. In our country, the majority of greenhouse use traditional trench border irrigation, and the use ratio is only40%, so the equipment and system of greenhouse irrigation lag behind the developed countries, meanwhile, the price of imported equipments is high and the variety is less so that this condition cannot meet the requirements of development of agricultural production. Just based on this background, and together with current status of system and equipment of greenhouse irrigation in my country, my study on control system of greenhouse irrigation was launched.In this paper, starting from the humidity circumstance that affects grow-up of the crop, decision-making factor of greenhouse irrigation was determined after analyzing, according to comparative analyses, drip irrigation was the method chosen for greenhouse irrigation, based on which, PLC was proposed as a site controller, and a set of control system of greenhouse irrigation was devised.Having designed the overall scheme, the author proposed PLC as the control system of the next crew. Then, after the design of the hardware of control system Mitsubishi FX2N Series PLC, dedicated A/D converter module, as well as sensors were selected.According to the characters of greenhouse irrigation environment, fuzzy control theory was introduced to irrigation control system. Despite greenhouse soil has features such as time lag, nonlinear and so on, strong robustness of fuzzy control meets the requirements of the system. In accordance with irrigation experience of long time operators and conclusion of practical irrigation from agricultural department, the regulation of fuzzy control was worked out, which, was referred to some successful instances, as well.Fuzzy controller achieves fuzzy control well with a carrier PLC, and by means of the program of PLC. Also, the author designed a set of irrigation control program based on the moving regulation of drip irrigation, according to which, the PLC programs achieved automatic closed-loop control of greenhouse irrigation. Meanwhile, the host computer man-machine interface was devised by configuration software, which achieved the following functions:monitoring system, giving an alarm, collecting data, inquiring real time and historical information and converting of manual with automatic switch.By means of the verification of simulated experiments, the final results indicate the feasibility of the programs and the host computer interface, also, the simulated verification based on MATLAB software manifests the superiority of fuzzy control in irrigation control.In a conclusion, the designed system meets the overall requirements, which provides a valid method for studying and developing control of greenhouse irrigation...