Research On Key Technologies Of ZigBee Wireless Sensor Networks Orienting Bridge Health Monitoring

Chongqing is located at the west of China, which has many mountainous and river.Bridge plays an important role in this city. The health of bridge directly affects the city’seconomic development and People’s Daily life, so the bridge health monitoring becomesthe important part of urban construction. Now, the main technology of the bridgemonitoring data transaction is using cable network. It exist many problems, such as thehigh cost of wiring cable network, the large consumption of manpower resource, theplenty of time on wiring cable network and the difficult work of changing wiring.However, wireless sensor network (WSN) has the low cost, low power consumption,self-organizing, and it has some advantages like easy operation, easy construction, andeasy deployment and so on. So the characteristic of WSN can effectively solve theproblem existing in the cable network.This paper analyzed the current large-scale bridges’ complex communicationenvironment characteristics. Spread spectrum communication (SSC) has verified aninterference effect of signal in the airtight environment. Then it optimized the routingprotocol algorithm. At the same time, it designed a set of wireless sensor networkgateway and nodes used in large-scale bridge health monitoring according to itscharacteristics. It enriched the means of large-scale bridge health monitoring, replacedthe previous bridge with wired sensor networks, avoided the disadvantages of wiredsensor networks, and also had the feasibility and practical value. So it is a newdevelopment direction of future large-scale bridge monitoring. The main content asfollows:First of all, in the transmission of signal, object reflection, scattering, object shelter,and other unknown interference in enclosed environment resulted in the path loss andmultipath fading phenomenon. It makes the wireless signal at the receiving end is veryweak. The spread spectrum gain processing technology can effectively deal with thesignal’s multipath fading phenomenon in the channel of complex interferenceenvironment. The simulation results verify the effectiveness of using anti-jammingmethods under simulated conditions of bridge box girder.Secondly, in terms of protocol optimization, this paper puts forward a optimizationalgorithm based on Cluster-Tree+AODVjr algorithm, and combines with the residualenergy node model to balance network energy. In this way, it can solve the problem that gathering node data and selecting the routing path are in low efficiency in the routingalgorithm path, at the same time, it also can solve the energy waste problem resulted bysevere flooding to improve the life of the entire network.Finally, we should consider the circumstance of bridge. Bridges always are in anextreme communication environment with high temperature, high humidity, highvibration and hermetic complex interference. This paper uses PIC24FJ128GA010thathas strong stability and high cost performance produced by Microchip Company as awireless sensor network (WSN) gateway microprocessor chips (MCU), also usingCC2530as wireless RF module to design a circuit system with stable performance,strong anti-interference ability. This whole system under a simulated bridge box girderin a complex environment should meet design requirements.