D-MAX DMC-20SEC Manual de usuario descargar pdf (Pagina 38)

If we suppose that the optimal size of image base is determined (and which cannot be exceeded)

and relevant images are collected resulting in a reasonably good image base. At this point

another question arises: how can the engineers update the database with new images? It is

very hard to determine which images from the new image-set need to be stored and which

images need to be deleted from the current image base. There are several criteria – such as the

date created, the number of similar images etc. – which can be used as the basis of the updating

decision but a precise numerical factor which shows the usefulness of pictures in the database

is much more difficult to determine.

The aspects and concepts mentioned in this section have shown that the usage and perfect

operation of automated optical inspection system requires human control and supervision.

Although the devices’ algorithms are able to execute fast, accurate, efficient, reliable, “assid‐

uous” and continuous inspection (they appear to be much more suitable than human operators

as a consequence!) without being fed sufficient intelligence they cannot adapt immediately

and independently to changes in manufacturing. Therefore the quality inspection process can

hinder the increased spreading of autonomous electronic manufacture.

Several researches and developments are focusing on the problem to redeem the status of the

human operators’ work and to provide help for AOI engineers. Very interesting research

directions are in automatic algorithm parameter optimization methods. The AOI devices on

the manufacturing line monitor the quality of the algorithms (number of false calls and slip-

through, if possible) and on occasions they adjust the parameters using the image base to create

a better, higher quality algorithm. The engineers only need to take care of special cases like

changing the lighting or creating new inspection methods. Although the automatic parameter

optimization methods do not have to satisfy high real-time criteria, it is important to determine

the optimized parameter values in a relatively short time. It is easy to verify that even in the

case of having some dozen parameters; the analysis of all parameter-combinations takes a very

long time (years) therefore heuristic search methods have to be used to solve the optimization

problem.

Figure 29. Quasi-tombstone

Materials Science - Advanced Topics

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D-MAX DMC-20SEC Manual de usuario Pagina 38