Study On Intelligent Control System Based On Internet Of Things In Facilities Agricultural Greenhouse

The content of this thesis is funded by “Study on the system of the construction project of Taiyuan to support the new rural”, based on the project of “The development and demonstration of adaptive control system in facilities agricultural greenhouse”(No: 120157). This task is proposed in accordance with the problems of the low level of environment regulation, the low degree of network and the insufficient of scientificity in operation, which restricts the raising of greenhouse productivity. An intelligent control system based on Internet of things was designed and developed, which can realize on-line monitoring of major parameters, automatic control of greenhouse actuators and scientific management of greenhouse. The goals that realizing the automation, intellectualization, networking and scientization of greenhouse are achieved, which has great significance on the promotion of greenhouse productivity and modernization level. The main contents of this paper are as follows:The overall controlling plan of greenhouse is made under the technical architecture of IOT after analyzing the characteristics and controlling requirements of enviromental parameters, which consist perception tier, transmission tier and procession tier. The whole system consists of one integrated control system, some field control systems and communication network. All the field control systems are managed and controlled by the integrated control system, and can run normally when cutting off from network. This controlling structure can meet the demand of greenhouses of different scale.As the environment sensor node and the intelligent control terminal, field control system belongs to the perception tier. According to the situation of greenhouse, the field control system based on PLC is designed. It adopts different sensors to detect air temperature, air humidity, illumination intensity, concentrations of carbon dioxide and soil humidity. The manual control and automatic control method are cooperatively used to control the actuators. The touch-screen is used to realize the man-machine interaction in the field of greenhouse. The SMS alarm module is used to realize the remote monitoring function.The communication network is the transmission tier of IOT. According to the controlling requirements of transmission tier, the data transmission system that combine greenhouse field LAN with remote WAN is build. The data in field LAN adopts the wired transmission mode based on Ethernet. The transmission technology of remote WAN data adopts internet and GSM mobile communication. The data of perception tier is transmited reliably and broadly.The integrated control system belongs to the procession tier, which realize the data processing, including data storage, data pre-processing, intelligent control and man-machine interaction. The concentrated monitor & management platform is developed based on LabVIEW. The data exchanging between the integrated control system and field control system is realized by OPC server. The database is developed based on SQL Server to realize the scientific management of operating data. A data pre-processing method that consists of software compensation, distributing diagram and averaging is proposed to eliminate the effection of data error. A variable structure fuzzy control method is proposed to improve the steady-state performance. The fuzzy controller is implemented by the PID and fuzzy control toolkit. The human-computer interaction interface of data acquisition, real-time monitoring, equipment control, parameter setting and data management is developed, which can improve the management efficiency.The greenhouse experimental platform is designed and constructed. The system has been tested on it. The experimental results show that the design of hardware is reasonable, communication network is stable and the functions of concentrated monitor & management platform is normal. The proposed data pre-processing method and variable structure fuzzy control method have good effects, which can stabilize the enviromental parameters on the reasonable level. In all, the system can meet the management requirement of modern greenhouse.