Adoption of machine vision inspection and computer image processing technology, an oil-seal dimension measuring system was developed to meet the requirement of online production and real time inspection. The makeup and principle of the system were introduced, as well as its working process and design requirements were described on detailed. The technique of quadratic filtering for image preprocessing combined with the principle of three points determining a circle, point Hough transform and the least squares was employed for image processing algorithm, and high precision sub-pixel edge detection was achieved. The measuring results of experiments demonstrated that the inspection goal on 100 percents of products could be realized successfully, and with many advantages such as non-contact, on-line, real time, appropriate precision and low cost, the system can be applied widely in other production fields.
