摘要
将动态摄影测量方法应用到风电叶片动态监测中,对于优化风电系统设计、保证系统安全可靠运行具有重要意义。图像特征点自动匹配是动态摄影测量系统中的关键技术,匹配方法的优劣直接影响最终的测量精度。在实际风电叶片动态摄影测量中,叶片运行时的摆振会加剧叶片的非平面性,使得直接采用极线或单应性匹配技术匹配双目图像特征变得更加困难,因此提出一种基于预筛选和局部单应性的双目图像匹配方法,可用于风电叶片平缓连续曲面测量场。首先,通过双目摄影测量系统获取叶片像点图,对左相机采集到的像点图通过极线约束筛选出各个点在右像面中的候选匹配点集;其次对当前待匹配点及其候选匹配点集中的每个点分别抽取一个以该点为中心的局部近平面区域并做相应组合;之后针对每一组近平面区域分别采用改进的随机抽样一致算法估计相应的最佳单应性矩阵模型;最后通过局部单应性变换及合理的误差阈值在多个候选点中确定当前待匹配点的最终匹配点。该方法已成功应用于风电叶片的摆振测量实验,像点匹配率不低于96%且匹配准确率不低于97%,能够满足实际风电叶片图像匹配精度的要求。
The application of dynamic photogrammetry to the dynamic monitoring of wind turbine blades is of great significance to optimize the design of wind power system and ensure the safe and reliable operation of the system. Automatic matching of image feature points is a key technology in dynamic photogrammetry system. The quality of matching method directly affects the final measurement accuracy. In the actual dynamic photogrammetry of wind turbine blades, the shimmy of the blades during operation will aggravate the non-planarity of the blades, which makes it more difficult to directly use the epipolar or homography matching technology to match the binocular image features. Therefore, a binocular image matching method based on pre-screening and local homography is proposed, which can be used in the measurement scene of wind turbine blades characterized by a smooth continuous surface. Firstly, the point images of the blade are obtained through the binocular photogrammetry system. For the point image captured by the left camera, the candidate matching point set of each point in the left image is filtered from the right point image through the epipolar constraint. Secondly, a local approximate plane region centered on this point is extracted for each point in the current point to be matched and its candidate matching points and all local approximate plane regions are combined accordingly. Then, for each group of approximate plane regions, the improved random sample consensus algorithm is used to estimate the corresponding optimal homography matrix model. Finally, the final point that matches the current point to be matched is determined in multiple candidate points through the local homography transformation and reasonable error threshold. This method has been successfully applied to the shimmy experiment of the wind turbine blade. The image point matching rate is not less than 96% and the matching accuracy is not less than 97%. The method can satisfy the requirements of actual wind turbine blade image matching for accuracy.
作者
李梦帅
燕必希
董明利
孙鹏
刘其林
Li Mengshuai;Yan Bixi;Dong Mingli;Sun Peng;Liu Qilin(Beijing Key Laboratory of Optoelectronic Test Technology,Beijing Information Science&Technology University,Beijing 100192,China)
出处
《电子测量技术》
北大核心
2022年第6期155-161,共7页
Electronic Measurement Technology
基金
北京市教委科技计划重点项目(KZ201711232029)
北京信息科技大学促进内涵发展科研水平提高项目(2020KYNH223)资助。
关键词
风电叶片
图像匹配
极线约束
近平面
随机抽样一致
局部单应性
wind turbine blades
image matching
epipolar constraint
approximate plane
random sample consensus
local homography
