Position Inspection System for Welded Nuts by Image Processing

This paper describes a design and trial construction of the welded-nut position inspection system which applies gray-scale image processing. The inspection is made as follows : 1st, define two square inspection areas which enclose a nut (= object) image. These two areas have a common center and different area sizes to each other. 2nd, calculate a standard density level by using 5 densities of pixels around the center. 3rd, count the number of pixels which density levels are lower than the standard one, in each area. 4th, judge the quality of the work by the difference between the counts at large area and that at small area. It is clarified by experiments at an industry that the system inspected with no error and with about 15 ms/object processing speed.