基于摄影测量和ERA改进算法的叶片模态辨识方法

Modal Identification Method of Blade Based on Photogrammetry and Improved ERA

在风力机叶片表面排列编码目标,基于双目立体成像原理和图像特征匹配与跟踪方法,可以动态、实时地获得编码目标的空间运动信息。针对噪声污染影响模态辨识的问题,通过奇异值分解(SVD)和Cadzow算法构造了无噪声污染的Hankel矩阵,有效减少由噪声引起的虚假模态。针对模态定阶过程容易出现虚假模态的问题,提出一种改进的特征系统实现算法(ERA)。相比于传统的ERA模态辨识方法,该方法在固有频率的识别上提高了3.6%的精度,获取了更清晰的稳定图。

Through arranging coded markers on the blade surface of a wind turbine,and based on binocular stereo imaging principle and image feature matching and tracking method,the spatial motion information of coded markers can be obtained dynamically and in real time.Aiming at the problem of noise pollution affecting modal identification,a singular value decomposition(SVD)and Cadzow algorithm was used to construct a Hankel matrix without noise pollution,which effectively reduces false modals caused by noise.In order to solve the problem that false modes are easy to appear in the process of modal order determination,an improved eigensystem realization algorithm(ERA)is proposed.Compared with the traditional ERA,the proposed method improves the accuracy of natural frequency identification by 3.6%and obtains a clearer stabilization diagram.