Width estimation of glue line for engine oil sump based on planar vision

A new method of glue line edge detection and width estimation is proposed for engine oil sump assembly in this paper. Firstly, the glue line image is preprocessed via Laplace of Gaussian operator to reduce the noise. The histogram equalization is applied on the image to adjust the contrast ratio. Secondly, the centerline and contours of the glue line are extracted by using morphological methods, such as thinning, contour finding, area computing and etc. Then glue line width is estimated based on the centerline and contours. The normal of the fitted centerline curve is calculated at each measuring position. The key points on the inner and outer contours are searched along the normal direction. The contours' segments selected based on the key points are fitted. Finally, the Euclidean distance between the two intersections of the centerline's normal and contours is computed and regarded as the glue line's width. The experiment results show that the proposed method has acceptable accuracy to estimate the width of the glue line.