Research On Structural Health Monitoring System Based On IEEE802.15.4

Structural Health Monitoring (SHM) diagnoses the condition of structures like buildings,dams and bridges, so the potential problems can be detected at early stage by examining theoutput of sensors attached to or embedded in the structure, which can avoid the danger ofcollapse, reduce the loss of human lives and improve the safety. Most traditionally existing SHMimplementations are wired data network systems to collect structural health information. Thiscan simplify the hardware design, however, there are problems such as installation, maintenanceof the network and high cost. In recent years, the integration of the technology of sensing andwireless networks has led to the rapid development of Wireless Sensor Networks (WSNs), suchas the low rate, low power, low cost IEEE802.15.4standard. WSNs have the advantages of easydeployment, low maintenance and flexible scalability. Wireless SHM based on IEEE802.15.4isa cost-effective monitoring method. The main work of this thesis is as follows:The basic concept, significance and state of the art of structural health monitoring aredescribed, and the key technologies involved in WSNs for SHM are analyzed.Applying the IEEE802.15.4standard for wireless personal area network to SHM is studied.Based on above research, the architecture and the principle of the wireless structural healthmonitoring system are described, and the hardware and software of the overall system aredesigned.The hardware platform is built. Wireless network nodes use the ATmega128Lmicroprocessor and CC2420RF module, which are connected with SPI interface. The choice ofsensors is studied and the signal conditioning circuit is designed. Some other peripheral circuitssuch as UART, clock and ISP are also implemented.The software for structural health monitoring applications is developed. The nesCprogramming language is applied. According to the principles of hardware abstractionarchitecture, the CC2420driver components (including the HPL components, HAL components)and the relevant part of the IEEE802.15.4protocol are designed and implemented which arebased on the TinyOS operating system. Meanwhile, under VC++6.0in Windows, amanagement platform on PC which can display and store the real-time sensing data is developedusing ActiveX control for industrial instruments and the technology of ado to access to thedatabase.For a large-scale networks, the WLANonSAN which is a two-tiered architecture networkwhere is an IEEE802.11wireless local area network (WLAN) on top of an IEEE802.15.4structure area network (SAN) is proposed as a solution, and OPNET Modeler is applied to analyse the performance of the two-tiered architecture network in terms of average end-to-enddelay, packet delivery ratio, average energy consumption which verifies its advantages. Thisgives some helpful guidance for practical projects.