大型风力发电叶片变形的摄像测量方法研究

Deformation measurement of large-scale wind turbine blades using videometrics

将摄像测量方法应用于大型风力发电叶片力学实验的变形测量中。叶片在发生大幅度整体变形的同时发生微小的屈曲变形,这给测量带来了很多问题,为此提出并联式组网测量的方法。固定像机大视场远距离交会测量整体变形;相对固定的立体像机小视场近距离交会测量叶片上每个长约3 m的局部段的屈曲变形,并且跟随叶片上待测量区域移动。所有像机并联式组网,同步触发。测量过程中的关键技术还有像机标定和畸变校正、格网点和黑白标志块的高精度半自动提取、坐标系的统一等。实验结果表明:整体变形的测量精度优于0.5 mm,屈曲变形中网格点三维坐标的测量精度优于0.1 mm;系统搭建相对简便、测量内容丰富、范围广、精度高、且能供事后处理和分析。

This paper attempted to use videometrics to measure the deformation of wind turbine blades in mechanics experiments. Given that the small buckling deformation occurs simultaneously with the large integral deformation to the blades brings many problems to the measurement, this paper put forward a PamUel Network Measurement （PNM） method by which all the concerned cameras were networked parallelly and triggered synchronously. It adopted a large view field and the remote intersection by fixed cameras to measure the integral deformation in case of large-amplitude deformation, and the close range intersection by relative fixed stereo cameras to measure the buckling deformation measurement of every local section of about 3 m in ease of tiny deformation. Stereo cameras moved with the sections where the large integral deformation occured. Key techniques involved in the measuring process also include the calibration and the distortion correction of the camera, the semi- automatic and high-precision extraction of grid landmarks and black and white markers, and the unification of coordinate systems, etc. Experimental results show that the accuracy of the integral deformation measurement is higher than 0.5 mm and that of the buckling deformation measurement is higher than 0. I nun. Besides, it provides a relatively convenient construction method for the measuring system, an abundant measuring content, a wide measuring range, higher measuring accuracy, and post processing and analysis.