The Design And Implementation Of Grain Monitoring System Based On Wireless Mesh Networks

Grain storage is an important part of food safety.Every year there is a huge loss of grain due to improper supervision in food storage.Therefore,it is particularly important to store grain scientifically.With the application of communication and electronic technology in the field of granary,the digital system has greatly improved the quality and efficiency of the management of grain storage.There exit many problems in the current measurement and control system for condition of stored-grain such as simple function,poor system compatibility,low data transfer rate and poor anti-interference ability etc..The key to these problems lies in wireless network transmission.In view of the existing problems in the system,combined with wireless sensor network technology,wireless Mesh network technology,sensor technology,intelligent control technology,embedded technology and so on,we design a measurement and control system for condition of stored-grain based on wireless Mesh network.The system includes a host subsystem,a Mesh network transmission subsystem and a data acquisition control subsystem.To solve the Key issues in wireless network transmission,the system is based on the characteristics of the building and the data service needs of the wireless network,using two layer network from the structure of network.Among them,The first level wireless network transmission structure is a single hop wireless sensor network based on the 470MHz module of Si4432,which is used to collect the data from each sensor node to its extension;Secondary wireless network transmission structure for the backbone transmission structure,the wireless Mesh network technology to carry on the design,in order to realize the extension data and video business data to the host subsystem grain situation of high speed,stable transmission.The main work of this paper is summarized as follows:1.In the data collection subsystem,aiming at the problem of high power consumption of plane sensor,it actualizes the functions that the extension set can awaken the jurisdictional plane sensor stably and rapidly by using the sleep mechanism of Si4432 RF module.Because of same frequency interference,the multi-position sensor can not upload data to its extension sets simultaneously.During the research and test in the minimum orthogonal channel bandwidth of Si4432 RF module,we design a wireless channel partition mechanism,which realizes the function that multi-position sensors upload data to their extension sets at the same time,and improves the measurement efficiency of the whole scene.As for the design of the software extension,we use a multi threading mechanism based on embedded Linux platform,realizing the efficient management of Si4432 communication thread,network communication thread,wireless Mesh network thread and equipment information synchronization threads.For monitoring equipment,we adopt the EPOLL mechanism,realizing the efficient management of real time acquisition module,dynamic object monitoring alarm sub module and the communication module.2.In Mesh network transmission subsystem,considering that the data of wireless sensor network convergence rate is low,combined the special network topology with Mesh network transmission technology,we design a backbone transmission mechanism based on multiple orthogonal sub channel allocation,and make corresponding simulation based on NS2 platform.The proposed scheme can improve the robustness of the backbone network,and the simulation results show that the proposed scheme can meet the requirements of the bandwidth and real-time requirements of the video data transmission.3.For host subsystem design,on the embedded ARM + Linux platform carried a local server,web server,streaming media server,and database,realize the environment detection,video view,alarm picture viewer,alarm information browsing and intelligent control,to achieve seamless docking with the cloud server.