Research On Monitoring Structural Modal Of ERA Method And Application Of Wireless Smart Sensor

It is important that structural modal parameters can be learnt in itsservice functoin. Noise is one of the main factors affecting the accuracy ofmorniroring those parameters. In this paper, using the random decrementTechnique or Natural Excitation Technique (NExT) combined withEigensystem Realization Algorithm (ERA) can reduce the impact of noise andimprove the precision of the ERA method. In structural vibration experiment,using wireless smart sensor helps data in real-time collection. Consequently,the performance of the wireless sensor was detected by experiments. The mainresearch of this paper is as follows:(1)Discussion of the ERA and its related methods in detailsThe basic principle of ERA method was discussed. Hankle matrix isformed from the raw data, by the relationship between the Hankle matrixsystems characteristic equation deduced system modal parameters. In order todemonstrate the rigor, two aspects of the system’s controllability andobservability were discussed. And lists the simple example was cited to carryon the analysis. In order to follow-up test, the sampling frequency theory andprocess was introduced in detials. Effective data processing is a prerequisitefor high-precision modal parameter，so this paper also introduced the randomdecrement technique and NExT. Lastly, two modal parameter criteriontheoretical bases were provided for excluding false modal.(2)Installation and testing of wireless sensorIn order to detect the performance of wireless sensor, this paperintroduced SHM-A the process of installation and testing, and discussed inopen environment, necessary hardware, source code compiler and so on.Wireless sensor static and dynamic calibration method were studied.(3)Approach to mixed usage of Wireless sensor and wired sensorProposed wireless sensor mixed with the wired sensor using the dataprocessing method. Through truss bridge experimental comparison, the twotypes of sensor mixed solving the feasibility of the modal parameters.(4) Random decrement technique or NExT combined with ERA, improved theprecision of ERA method.The grid structure of Suihua unviersity Gymnasium vibration testing,results of sovling modal parameters of random decrement technique/ERA orNExT/ERA compares with directly/ERA, the data after random decrementtechnique or NExT has a higher precision.