Design Of Greenhouse Monitoring And Control System Based On Zigbee Wireless Sensor Network

Greenhouse cultivation is an major part of facility agriculture. Most of the existing greenhouse control systems use the wired transmission mode. They have difficulties in wiring and repairing. Even the greenhouse control system using the wireless transmission mode also has defects such as single function, poor extensible and low precision.The emergence of internet of things and wireless sensor network has accelerated the integration of agricultural modernization, robotization and informatization. It has promoted the transformation of agricultural production from traditional mode to intelligent mode. ZigBee protocol has many features such as low power consumption, low cost, short transmission distance,low data rate and self-organized. It is especially suitable for use in wireless sensor network.After analyzed the current development of greenhouse control system both here and abroad and the actual situation of Chinese agricultural production, the paper designed the greenhouse control system based on ZigBee wireless sensor network. The system is split into the sensing layer, network layer and application layer on the basis of the function. The paper has carried on the design of the sensing layer and application layer. The sensing layer uses the star topology structure of wireless sensor network. Sensor nodes periodically monitor greenhouse environmental information and transmit it to the coordinator nodes through multicast communication. The coordinator node fuses and sends the information from terminal nodes to the network layer. The coordinator node also transmits the information from the network layer to terminal nodes to control them. The network layer connects the sensing layer with the application layer and completes the conversion between different protocols. The application layer has many functions such as data display, parameter setting, information release and so on. The cloud server which is configured on demand improves the operation ability, extensibility, safety and dependability of the system. The system sets greenhouse measurement and control, weather forecasting, agricultural technology release and other functions into an organic whole and provides an agricultural Internet of things overall solution for the user.There are many characteristics in greenhouse humidity and temperature such as strong coupling, large lag, non linearity and so on. The precise mathematical model cannot be established in the system, so is not suitable for the use of conventional control method. Fuzzy control does not need precise mathematical model and realizes the precise control through fuzzy reasoning based on expertise. Fuzzy control and fuzzy compensation decoupling algorithm is applied to the system and effectively solves the problems existing in greenhouse temperature and humidity. The system wins the high control precision.