Design And Implementation Of Laboratory Environmental Monitoring System Based On ZigBee

Laboratory as an important place for teaching and scientific research in institutions of higher learning,storage of a large number of sophisticated scientific research equipments,and also includes a number of flammable,explosive,toxic and other dangerous items.Coupled with it often be used frequently and it has personnel concentration and mobility,so it often causes emergency.In the serious threat to personal safety of teachers and students at the same time,there will be a huge loss of property to the school.Therefore,how to ensure the safe and reliable operation environment of scientific instruments,and ensure the safe storage of dangerous articles,and reduce the hidden dangers of personal and property has become a concern of the society.Under this background and according to the demand of laboratory environment monitoring,this paper designs a laboratory environment monitoring system based on ZigBee,by studying ZigBee technology,wireless sensor network technology and ZigBee anti-interference technology.In addition to study the related interference technology,this system could resist the interference of WiFi.And this system realizes the collection,transmission and processing of temperature,infrared data in wireless sensor network.And finally this system achieves the purpose of monitoring the laboratory environment.The specific results achieved in this paper are as follows:(1)According to the requirements of laboratory monitoring system in university,this paper designs the overall structure of the monitoring system: Using wireless sensors for data collection of the environment.And through the coordinator of the USB serial port sensors could connected with the computer side.And computer through the analysis of the data packet processing,the relevant information will be stored to the database.Finally the data that achieves could statistics and be displayed through the database connection.In the selection of node hardware,there are a variety of models of chip analysis and comparison on the current market.With the consideration of cost,the system decided to use TI's CC2530 chip,Chengdu Wireless Dragon's SMBD-14 floor,GDH high precision temperature and humidity sensor and HC-SR501 humaninfrared etection sensor.(2)By analyzing the existing interference detection technology and the interference avoidance technology,I found most algorithms judge the network is suffering from WiFi interference or not only by receiving signal strength indication or packet error rate.And this judgement is not reasonable,which leads to the error of judgment.Therefore,this paper proposes an improved interference monitoring method based on link quality and PER.The method can determine whether the WiFi interference by analyzing the error rate of common nodes and important nodes,the proportion of nodes with error packet rate,the link quality and the received signal strength.In the method of interference avoidance,most of the algorithms are time-consuming and resource-consuming.So this paper improves the selection method of the channel,and adopts the way of before and after the scan,until the appropriate channel is found,and improves the speed of avoidance.(3)The design of ZigBee network is realized in Embedded Workbench IAR 8.10 development platform,including: initializing the network,the establishment of network routing,network merging and segmentation,temperature and humidity and human body infrared collection,the node temporarily out of the network and detect fault section.Through the Visual Studio 2010 development environment can achieve the development of the host computer and web site.Through SQL Server 2008 R2 database management system can achieve the creation of the database and data storage.The design of environment monitoring system based on ZigBee is completed by using C and C #language.The collection,transmission,analysis,storage and statistical display of environmental information are realized.The management of user information and monitored room information is realized.The performance of the system was tested in detail.