利用LabVIEW实现拉索振动信号的精确频谱分析  

Precise Spectrum Analysis of Cable Force Signal Based on LabVIEW

作　　者：傅琦[1] 邓焱[1] 乔陶鹏[1] 

机构地区：[1]清华大学精密仪器系,北京100084

出　　处：《计算机测量与控制》2004年第11期1011-1013,1017,共4页Computer Measurement &Control

基　　金：国家自然科学基金资助项目(50105010)

摘　　要：斜拉索的索力检测是检验斜拉桥的重要环节。一般采用频率法,其中索力与拉索振动信号基频测试的准确性有直接关系。计算频谱常用FFT算法,但由于其栅栏效应误差较大,想要提高分辨率只能增加时长。为了提高测试效率,求得精确索力值,在LabVIEW环境下,首先利用FFT算法得到各阶频率估计值,然后利用DTFT算法对局部范围峰值进行搜索,进而得到各阶频率精确值。系统在军都山渡槽桥试验中得到了很好的验证。试验结果表明系统在不增加测试时长情况下能有效提高斜拉索固有频率估计的精度,从而能得到精确索力值。Measuring the cable tension force is important to cable-stayed bridges. Frequency method is widely used and there is a direct relationship between cable force and vibration frequency. To estimate each order of natural frequency, FFT algorithm can be used. But the picket-fence effect of FFT algorithm reduces the measuring precision. To reduce the picket-fence effect and increase the measuring precision of certain special frequency, the spectrum analysis system which uses DTFT algorithm is realized based on LabVIEW. The system determines a rough frequency range of certain natural frequency by FFT first, searches the peak values within this range through DTFT algorithm, and then works out the more precise frequency. Practical application in Jundoushan Aqueduct shows that the system satisfies the needs of fieldwork. Experiment result also proves that system can improve the measuring precision effectively and then get the more accurate cable force in the case of not increasing the measuring time.

关 键 词：索力 斜拉索 斜拉桥 测试效率 频率法 振动信号 基频 FFT算法 频率估计 VIEW 

分 类 号：TP311[自动化与计算机技术—计算机软件与理论] U448[自动化与计算机技术—计算机科学与技术]