An Irrigation System Design For Green House Tomatoes Based On ZigBee Wireless Sensor Networks And Fuzzy Control

China is a traditional agricultural country, where the water irrigation efficiency is awfully limited. And large-scale cultivation of cash crops needs precise control of the environment. Therefore, research on the intelligent irrigation system to optimize the water usage acooding to the crops demand is of great significance. With the progress of technology, wireless sensor networks are being used in a lot of information acquiring fields. As an emerging wireless sensor network protocol standard, ZigBee is applied in industry, medicine, agriculture and other fields, thanks to its extremely low power consumption, low cost and high reliability.In this thesis, the R&D situation at home and abroad in intelligent irrigation is analyzed. Based on ZigBee communication, deficit irrigation strategy and fuzzy control theory, an intelligent irrigation system is given with application in the greenhouse tomatoes as an example. A modified ZigBee tree routing is proposed and simulated in the NS2 platform. The main content and innovation of this thesis are summarized as follows:1) Under the guidance of modular design, the core board for the irrigation system is completed, taking JN5139 as the ZigBee supported chip. Different function nodes are created just by adding relevant modules such as sensors and valve controllers. It makes the ZigBee system easy to be expanded.2) The intelligent irrigation architecture includes the ZigBee communication system, the ARM centralized controller and the sprinkler system. Tests show that the whole architecture is reasonable, reliable and of stable performance.3) After analyzing shortages of the existing irrigation strategies and key environmental prameters influencing greenhouse tomato irrigation, an intelligent irrigation strategy is proposed based on ZigBee communication features, deficit irrigation strategy and fuzzy control. It consists of a fuzzy control irrigation module and a forecast irrigation module. The Fuzzy control irrigation module sets the optimal earth humidity according to crop current growth cycle in real time. The forecast irrigation module calculats the transpiration and soil hydraulic conductivity by using air temperature, humidity, light intensity and earth humidity. Then it predict the irrigate time, and wakes up the relevant nodes to collect data. The whole irrigation strategy is simple and reasonable. Collecting data by request reduces the amount of environmental parameters transmission and saves the network energy.4) With the analyses of the defects of the ZigBee traditional tree routing and the irrigation system data acquisition features, a neighbor nodes energy evaluation function is proposed. ZigBee Network tree routing is conducted with this evaluation function. The simulation results in NS2 show that the modified tree routing has higher transmission efficiency than the traditional one, increasing by about 30%, saving the energy consumption of the entire network, extending the life cycle of a single node.