基于视频相位的拉索振动检测

Cable Vibration Detection Based on Video Phase

作为斜拉桥的重要受力构件,斜拉索的振动检测对桥梁健康监测具有关键作用.在实验室理想条件下,传统的空间相位振动检测算法能够实现结构振动的高精度测量,然而在实际场景下,环境因素如车辆、风激励以及拉索与地面的角度等会对测量结果造成较大的误差,因此其不适用于实际场景下的拉索振动检测.针对此问题,本文提出了一种基于方向自适应复可控滤波器的拉索振动频率检测算法,用于实现在真实场景下拉索振动的精确测量.首先,利用拉索的直线特性检测拉索位置,并确定拉索主振方向;其次根据拉索的振动方向特性,设计方向自适应复可控滤波器组,对视频的每一帧图像进行分解处理,得到不同尺度同一方向的相位谱和幅度谱,并对拉索边缘区域相位进行增强;最后将每一帧图像处理得到的不同尺度的空间相位进行平均,按时间顺序排列生成相位序列,对提取到的相位序列进行傅里叶变换得到拉索振动主频频率.通过与加速度传感器测量结果比较,证明本文算法鲁棒性较高,能够满足真实场景下桥梁拉索振动测量的应用需求.

As an important load-bearing element of cable-stayed bridges,vibration testing of stay cables plays a key role in bridge health monitoring.Under ideal laboratory conditions,the traditional vibration detection algorithm with spatial phase can achieve high-accuracy measurement of structural vibration.However,in practical scenarios,environmental factors such as vehicles,wind excitation,and the angle between the cable and the ground can cause large errors in the measurement results.Therefore,the traditional algorithm is not suitable for cable vibration detection in these cases.To address this problem,this study proposes a cable vibration frequency detection algorithm based on directional adaptive complex steerable filters to precisely measure cable vibration in real scenarios.Firstly,the linear characteristics of the cable are used to detect the location of the cable and determine the main vibration direction of the cable;secondly,according to the vibration direction characteristics of the cable,a directional adaptive complex steerable filter is designed to decompose each frame of the video,so as to obtain the phase and amplitude spectra of the same direction at different scales and enhance the phase of the edge region of the cable.Finally,the spatial phase of each frame is averaged,and the phase sequences are arranged in time order to obtain the main frequency of cable vibration by Fourier transform.By comparing the results with those of acceleration sensors,it is proved that the proposed algorithm is highly robust and can meet the application requirements of bridge cable vibration measurement in real scenarios.