The Application Of Wireless Sensor Networks For Experimental Modal Analysis

Experimental modal analysis is an important measure to analyze the dynamical features of complex structure, which plays an important part to structure design, vibration control structure damage estimate and health monitoring. In the experimental modal analysis, the main method for data acquisition based on cable connected, wired data acquisition system is more complex, high cost of deployment. And after it deployed, the system's maintainability and scalability is poor, particularly for some large-scale structure modal analysis equipment, the disadvantage is more apparent. The Wireless Sensor Networks(WSN) has many excellent features, such as simple structure, low maintenance cost, convenient deployment and good expansibility. Using WSN for experimental modal analysis data acquisition can compensates for the disadvantage in traditional data acquisition methods,better services for engineering practice. In the background of experimental modal analysis, the network topology, network routing and multi-measuring points synchronous data acquisition method have been studied,the mode parameter identification method of short sample was also studied. In the last, a data acquisition system for experimental modal analysis was developed. It has an important significance for the application of WSN-based experimental modal analysis.The key technology and difficulties of WSN in experimental modal analysis were summarized, the network topology, network routing and multi-measuring points synchronous data acquisition method were studied. Based on virtual pairs of cluster-head, the cluster-based routing and Time synchronous algorithm are proposed. Time synchronization combined with network routing can adapt well to data acquisition of experimental mode analysis, lowing the power consumption of the node.Because WSN can only acquire short data sequence signal under high sample frequency, an optimizing method of FRF based on segmented spectrum zoom is proposed. This method can improve the precision of FRF, with out increase the data sequence. Simulation and experiment indicated that the proposed method can effectively enhance the precision of mode parameter identification.Based on MICAz sensor node and MoteWorks WSN development platform, series components were designed and developed, such as fast data acquisition, data reliable transmission, cluster-based routing based on virtual pairs of cluster-head and time synchronous. Finally, the modal analysis experiment platform for WSN-based is built, and carried out an experiment on a motor structure. By comparing the result with that of wired data acquisition system, the practical use of this system was verified.