壓電智慧梁之系統識別與感應

System Identification and Sensing of A Piezo-smart Beam

施博瀚(Po-Han Shih)

指導教授 ： 尹世洵

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2009年)

https://doi.org/10.6841/NTUT.2009.00376

摘要

本文是利用時間域識別法中的直接系統參數識別法(Direct system parameter identification，DSPI)進行系統識別，首先以數值模擬的方式，分別在不同形式的外力作用下產生輸入與輸出歷時反應進行系統識別，利用無因次分析(Dimensionless analysis)找出識別時所需的取樣時間間隔，之後以有限元素法(Finite element method)模擬兩端固定支承梁結構系統，並產生輸入與輸出歷時反應進行系統識別時，發現在梁的兩側施加對稱形式的彎矩外力，只會識別出奇數模態，在梁的兩側施加反對稱形式的彎矩外力，只會識別出偶數模態。之後將直接系統參數識別法應用於實驗分析，本實驗是以壓電型智慧材料(Piezo-smart material)作為致動器(Actuator)產生振動訊號，再以位移計量測到的反應進行系統識別，首先對兩端固定支承梁結構系統識別自然頻率及阻尼比，之後將壓電智慧梁與系統識別應用於感測系統上，利用識別出的自然頻率來感測出懸臂梁上增加的質量與懸臂梁沒入水中的深度。

關鍵字

壓電型智慧材料 ； 直接系統參數識別法 ； 無因次分析 ； xPC target

並列摘要

This study uses the direct system parameter identification (DSPI) method to identify the system parameter (e.g. natural frequencies, damping ratio and mode shapes) in time domain. The DSPI method are applied to numerical simulation and experimental analysis.
In numerical simulation, first we simulate a single degree-of-freedom system subject to different types of external force (input) and obtain the time series of the displacement of the structure (output). Then, we find the optimal sampling interval in the process of identification which can accurately identify system parameters. Next, we simulate a two-fixed-end beam by a finite element method. We find that the system parameters of odd modes can be identified when symmetric moments are exerted on both ends of the beam. On the contrary, the system parameters of even modes can be detected when anti-symmetric moments are applied.
In experimental analysis, we fabricate a two-fixed-end beam and a cantilever beam with two piezoelectric patches bounded onto both surfaces of the beam near the damped location. These beams can be excited to vibration by applying the voltage to the piezoelectric patches to generate moments. The non-contact displacement sensor is used to measure the dynamic response of the beam. Based on the measurement data, the system parameters of the beams are identified by the DSPI method.
Finally, the self-excited piezo-smart beam combined with the DSPI method is applied in a sensing system. The changes in the natural frequencies are identified to sense a mass added to the cantilever and to detect the immersed depth of the beam in water.

並列關鍵字

Piezo-smart material ； DSPI ； Dimensionless analysis ； xPC target

參考文獻

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