Abstract:

In order to automatically inspect chip components, a vision-based method is proposed to calculate the geometrical parameters of the components. In this method, first, the coarse location of chip components and the edge point sorting are realized by means of the maximum external rectangle method, and the precise location of the edge is implemented by using the Canny operator and the Zernike moment operator. Next, the edge points are sorted into 4 parts according to sorting points, which are then fitted respectively via line and arc fittings to obtain the corresponding accurate values. Moreover, the stripe direction of the transverse image of chip components is correctly judged according to the image characteristics obtained via the fast Fourier transform （FFT）. Finally, an experiment is carried out, with a subpixel location precision of 0.03 pixel, a line fitting precision of O. 03 pixel, an arc fitting precision of 0. 05 pixel and a stripe direction accuracy of the transverse image of 100% being obtained. The results indicate that the proposed inspection method is of strong stability, high precision and excellent real-time perfor- mance, which is helpful in the automatic Vision-based inspection of chip components.

Key words: chip component, subpixel, vision inspection, fast Fourier transform, edge detection, fitting