Machine vision system for inspecting electric plates

This paper presents a machine vision system for automated visual inspection of plates of electric cookers, with the goal to reduce labour cost and ensure consistent product quality. A number of dimensions of an electric plate are accurately defined by using two cameras with telecentric lenses, by applying sub-pixel edge detection techniques, and by semi-automatically calibrating the system. The dimensions of plates, which are manufactured by CNC lathes, may fall in or out of prescribed tolerance standards and are as such a valuable indicator of the lathe tool blunt or breakage. Extensive experiments showed that the inspecting system is fast, accurate and robust. The machine vision system is, thus, able to keep up with the plate production process, inspect every plate and reject the defective ones. (C) 2002 Elsevier Science B.V. All rights reserved.