Surface parameters measurement for braided composite preform based on gray projection

Abstract

In this article, a method based on gray projection is proposed for automatic measurement of surface braiding angle and pitch length of braided composite preforms. The surface braiding angles are measured by rotated gray projection. First, the original image is preprocessed using Lab transform and block-matching and three-dimensional filter. Then, edge map of gray scale is acquired based on phase congruency and non-maximum suppression. Third, edge direction angles are computed by image rotation and gray projection. Finally, the average surface braiding angles are measured from the edge direction angles. The pitch lengths are measured by cropped gray projection. First, the original image is filtered by an artistic edge and corner enhancing filter. Second, block images are cropped based on gray projection. Finally, pitch lengths are measured by block images gray projection. Experimental results show that the proposed method can achieve the automatic measurement of average surface braiding angle and average pitch length of two-dimensional braided composite preform with high accuracy.