應用布拉格光纖光柵感測器於懸臂梁受撞擊之抑振研究

Apply Fiber Bragg Grating Sensor to Impact Vibration Control of Cantilever Beam

廖恆增(Heng-Tseng Liao)

指導教授 ： 馬劍清

國立臺灣大學/工學院/機械工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02411

摘要

以往對於懸臂梁的抑振控制，大多使用壓電感測器，雖然有不錯的感測效果，但將壓電片黏貼在懸臂梁上，其質量和體積對於懸臂梁的性質會產生一定程度的影響，所以本文將利用質輕、體積小的光纖光柵感測器做為懸臂梁抑振控制感測器，並使用對暫態訊號有高靈敏度的能量調變解調方法，對受撞擊之懸臂梁加以抑振。
為了達到良好的控制效果，在開始控制前先對懸臂梁系統的基本特性加以分析，其中包括懸臂梁本身、壓電致動器與布拉格光纖光柵感測器與黏貼壓電片後懸臂梁性質的改變。本文使用的布拉格光纖光柵感測器分為量測應變的平貼式與量測位移的垂直式，除此之外為了確保量測的正確性，也同時利用應變規與雷射都卜勒振動儀作分別作為應變與位移量測結果的比較。
本文使用將各模態分別控制的方法對懸臂梁加以抑振，首先針對單一共振頻加以抑振，並利用控制單一共振頻所得之方法及參數應用控制懸臂梁受鋼珠撞擊之暫態運動，由實驗的結果得知不論是垂直式或平貼式光纖感測器對懸臂梁的第一共振頻都有良好的抑振效果，兩感測器最大的差異在於，垂直式光纖感測器對高頻訊號有較高的靈敏度，可以量測到暫態運動最初始反應的細節，但量測高頻訊號會產生相位差，使得高頻模態控制的效果沒有平貼式光纖感測器來的好。
除了單一次的鋼珠撞擊，為了測試本抑振系統對於多次撞擊的抑振效果，本文利用塑膠球的多次彈跳及兩顆鋼珠撞擊實驗，証實了本系統對長時間多次或極短時間多點的撞擊都能有良好的抑振效果。

關鍵字

懸臂梁 ； 撞擊 ； 抑振

並列摘要

Generally, most people apply piezoelectric sensor to vibration control of cantilever beam and get good performance. But piezoelectric sensor would change the original property of cantilever beam due to its volume and mass. In this thesis, we choose fiber Bragg grating (FBG) sensor which has tiny mass and volume as control sensor. By applying intensity-modulated FBG which has high sensitivity to dynamic measurement, we can deal with impact vibration control of cantilever beam.
In order to get good control performance, we should investigate properties of the system including cantilever beam, actuator, sensor and cantilever beam combining with PZT. There are two types of FBG sensor be used here, surface-mounted type for measuring strain and vertical type for measuring displacement. In order to attest the accuracy of FBG measurement, we also used strain gauge and LDV as sensor at the same time.
We use separating modes method to design the controller. First we aim to single mode control and then apply these methods and parameters to impact control. According to the result of experiment both type of FBG sensor can successfully control first mode. However vertical type FBG sensor has higher sensitivity to high frequency modes. But it also has phase delay when measuring high frequency mode, the performance of high frequency mode control isn’t as well as surface-mounted type FBG sensor.
In order to test muti-impact control ability, we use plastic ball which can bounce several times on cantilever beam and two steel balls as impact source. The experiment result shows that this vibration control system can successfully control long-time muti-times impact and short-time muti-points impact.

並列關鍵字

cantilever beam ； impact ； vibration control

參考文獻

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