Research On Several Foundational Theories And Key Technologies Of Wireless Sensor Networks Orienting Engineering Structure Health Monitoring

The primary advantages of wireless sensor networks are reduction of system wiring, high monitoring precision, convenience for remote supervisory and controlling, easiness of system diagnosis and maintenance, and good fault-tolerant ability, etc. There is wide application prospect of wireless sensor networks in such fields as military affairs, environment protection, project inspection, medical treatment and so on. The basic task of wireless sensor networks is to obtain the valuable information of the physical world accurately. Wireless sensor networks can realize high speed, low time-delay message exchange among sensor nodes depending on the time and position information. So it can ensure the high accuracy and real-time characteristic of the whole measuring and controlling system. Wireless sensor networks face many-sided restrictions such as calculating, storing and network bandwidth. It is very important to investigate the system architecture of the wireless sensor networks, node localization, data fusion and network data management, etc.First of all, the system architecture and related theories of wireless sensor networks were studied and discussed in detail. The basic composition of network protocol stack and the characteristics of every layer's network protocols were analyzed by comparing blue tooth networks with ad hoc networks. Then three types of management models for wireless sensor networks were proposed. The characteristic analysis of network layer routing algorithms were emphasized, and several popular routing algorithms applied to wireless sensor networks were classified, compared and analyzed in this thesis.Then a kind of novel system hierarchical model of multi-hop wireless sensor networks was proposed on the base of analyzing existing network layer protocols. The traditional network system structure offers the network transmission support for various kinds of application program with the purpose of data transmission. The network node only has a transmission function, and it doesn't deal with data exchange. On the contrary, sensor network is focus on sensing data, of which the aim is to obtain more accurate characteristic information of the perceiving targets for a long time. The design of this system structure followed the principle of energy conservation. It realized the routing algorithm of multi-hop wireless sensor network. It has good expandability, and it is suitable for the large-span space application environment. At the same time, the data fusion technology was also used in the network protocols so as to achieve the goal of saving storing resources and reducing the network bandwidth occupation.The basic theory of data fusion for wireless sensor network, as well as data fusion at different levels were discussed and analyzed, and various data fusion structures were summarized in this thesis. A Kalman filter-based multi-sensor data fusion algorithm was presented based on the elaboration of the key issues of data fusion. Experiments for the algorithm were given; the simulation results indicated that the method was simple and practical. Meanwhile it performed higher data accuracy than simple sensor filtering. The algorithm has been realized among the prototype system, and experiment result shows the algorithms presented above have good execution efficiency and very kind expansibility.Analysis of stream feature of the wireless sensor network data and basic theory of data stream management were presented. On this basis, multi-inquiries and multi-stream data management algorithm of wireless sensor networks based on dividing inquiry blocks was proposed in this thesis. Through simulation, the algorithm can be seen as more and more inquiries on the data-stream processing with the obvious advantages of energy saving. From the perspective of data stream management, the redundant degree of data in the entire sensor network can be decreased to a great extent. At the same time, it can save storing resources and bandwidth occupation of the network and achieve the purpose of saving energy. From the analysis, the algorithm is suitable for solving the problems of data stream management of with a large volume of data.In the end, the conception and the significance of engineering structure health monitoring were analyzed. The structure and composition of engineering structure health monitoring system were discussed. On the basis of above theoretical study, the structure of engineering structure health monitoring based on wireless sensor networks was proposed and the hardware and software design realization of the system was given. The system has a clear designing structure and very kind expansibility; it strengthens the monitoring capability, widens the monitoring scope for engineering structures by introducing wireless sensor technology.