Study On The Key Technologies Of Wireless Sensor Network Based Greenhouse Ranges Monitoring & Control System And Its Realization

Greenhouse automatic management is an important research field during protected agricultural developing. A large monitoring and control network consisting of many sensors and actuators is needed to cover the large greenhouse ranges. Parameters such as air temperature and humidity, solar radiation, soil humidity, EC, pH should be collected in such a controlling system. Wireless sensor networks (WSN) ares thought preponderant to meet the greenhouse requirements and replace the wired connections in traditional systems. Wireless greenhouse management system integrated of wireless sensor network and automatic control technologies is the future direction which achieves optimized control in production process.This paper proposed a ZigBee technology based wireless sensor network monitoring and control system applied for greenhouse ranges management after studying some key issues and system architecture including devices hardware and software design and testing. The main content is listed as follows:(1) The applicability of wireless sensor networks in greenhouse ranges monitoring and control system was studied according to the analysis between the greenhouse development requirements and characteristics of WSN. Feasibility using wireless sensor network technology to solve the problems in the traditional wired connections system was investigated in detail.(2) The reason why ZigBee technology was adopted to build the WSN-based greenhouse ranges monitoring and control system was given by comparing the current short distance wireless technologies. ZigBee takes on advantages of low-cost, large network capability, low-rate and low energy consumption which are more suitable for greenhouse application.(3) The solution of ZigBee technology-based wireless sensor network monitoring and control system applied for greenhouse ranges management was given according to the greenhouses layout and WSN topologies. The key issues to conduct such a system considering the greenhouses production practice were also presented making preparations for the following research.(4) A routing method for greenhouse ranges wireless sensor network monitoring and control system was proposed. Based on the study of wireless sensor network routing protocols and ZigBee communication mechanism, we developed a greenhouse number-based routing protocol (GNRP) considering traits in greenhouse application. The analytic results showed that GNRP can reduce the routing overhead and improve the network performances.(5) The applicable data fusion methods for greenhouse ranges wireless sensor network monitoring and control system were explored. The greenhouses sensor network topology implied three instances for data fusion, and the corresponding disposal means were discussed in detail. The adaptive weighted fusion algorithm was applied in the first instance fusing the data from several same type sensors such as air temperature sensors in a greenhouse, which can acquire higher precision fusion value and reduce the data transmission volume. The packet aggregation technology was used to:1) combine the different kinds of greenhouse intra sensor data like air temperature, humidity and solar radiation to a single-greenhouse packet.2) combine the several single-greenhouse packets to a multi-greenhouse packet, which both occur on the local greenhouse controllers. These packets were all transmitted to the coordinator in the network, so they had the same frame head and the payloads can be aggregated. The performance analysis showed a good effect on improving the precision and reducing energy consumption and network busyness.(6) The greenhouse ranges wireless sensor network monitoring and control system was finally implemented. The system architecture and the whole technical and functional components were presented, and the roles and functions of all the devices in the system were also introduced. The common hardware structure was designed under the guide lines of electronic elements choosing which can be configured to devices by plugging respective modules. This plug and play design was convenient for installation and maintenance and helped to reduce the device cost. The devices and system running test results was satisfying.