Research On Technologies Of Networking In Wireless Sensor Network For Structural Health Monitoring

Structural health monitoring based on wireless sensor networks(WSN) is a hot research topic in many fields in the past years. Using wireless sensor networks technology in structures monitoring can meet the needs of multipoint and real-time efficient monitoring, which has the rapid deployment, self-organize into networks and distributed collaborative computing features. Currently, research in this area mainly includes networking technology, network management method and system validation studies and so on. Among them, network technology of wireless senor networks is the premise and foundation for structural damage identification accuracy. For structural monitoring, especially in aerospace structures, this paper carries out a deep research on the key technologies and implementation methods in networking technology.The main research contents include the following aspects:(1) For active structural health monitoring requirements, a kind of high-speed wireless piezoelectric sensor node is designed for structural health monitoring of engineering applications. The node consists of a piezoelectric excitation signal modules, piezo signal conditioning circuits, data processing module and wireless communication module. Every module in the system is tested through two experiments; the first test is the signal Stimulus and high-speed data acquisition, the second experiment is to verify the active monitoring function of screw loosening. The results show the designed wireless piezoelectric sensor node has a good performance.(2) In order to meet the application requirements of real-time, reliable, and high-frequency sampling in structural monitoring, this paper propose the protocol stack structure for wireless sensor networks in SHM. A network topology based on two-star-cluster and effective fixed routing mechanisms are also presented.(3) This paper proposed a method of redundant communication mechanism with dual base station and multi-level CRC verifi mechanism to improve the reliability of data transmission applications in SHM. To meet the special requirements of time synchronization for SHM, we proposed an improved FTSP time synchronization algorithm to exclude the disturbance of the outliers, and the results are robust.(4) Since sensor’s number and variety are large, this paper study the data compression method based on the compressive sampling technology for piezoelectric response data. A data compression method, which is called “Compressive Sensing, CS”, is proposed to apply to active structural monitoring. The processing of CS method is that: First, response signal x are measured onto the measurement data vector y through inner products with random vectors, where y is the linear projection of x and it is permitted to lose part of response signal x in the data transmissions. Next, when the base station receives the incomplete data, the response signal x can be reconstructed from the data vector y using the CS method. Finally, the test of active structural damage identification on LF-21 M aviation antirust aluminum plate is proposed. The response signal gathered from the aluminum plate is used to verify the data compression ability of the proposed method.