Correlation between Roughness (Ra) and Fractal Dimension (D) Using Artificial Vision Systems for On-Site Inspection

José Gabriel Ayala Landeros, Victor Manuel Castaño Meneses, María Blanca Becerra Rodríguez, Saulo Servín Guzmán, Sonia Elizabeth Román Flores, Juan Manuel Olivare Ramírez


A set of images of metal pieces with different finishes was obtained for use as a standard reference in the estimate of the surface roughness (Ra) through the fractal dimension (D) of the power spectrum and the spectrum of intensities. A system of artificial vision with two sources of LED light illumination (white and red) and three angles of incidence was used.  The best results were found with the spectra of intensities regardless of the type of lighting or the angle of incidence.  The values of the fractal dimension were correlated with the surface roughness values obtained with a contact profilometer to build regression curves that are used to estimate the surface roughness on site with a statistical error under 5%. This system could be used as an inspection station to reduce waiting times and unnecessary transport (Poka Yoke System).


Fractal dimension, Wigner distribution, power spectrum, roughness, Poka Yoke

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