Assembly completeness inspection method using active ranging

A method for completeness inspection of an assembled structure, said structure comprising a body shell and mounted parts, to check whether said structure has all the mounted parts that the said structure should have, said method comprising the following steps of:

• scanning the whole assembled structure with an active ranging scanner, thus obtaining a point cloud forming a 3D picture of the whole structure;
• obtaining a 3D model of the whole structure as it should look like in the assembled state based on CAD data modelling the assembled structure, said 3D model including a set of desired mounting parts;
• subdividing said 3D picture into a number of ever smaller picture comparison areas and said 3D model into a number of ever smaller corresponding model comparison areas, while, after each subdivision, overlaying each corresponding picture comparison area and model comparison area using a best fit algorithm, said best fit algorithm trying to match salient geometrical features of both areas and then outputting a deviation value D representing the residual deviation in the positions of the matched geometrical features, wherein said subdividing is stopped when the deviation value D is smaller than or equal to a distance between adjacent measurement points on the scanned surface, thus obtaining a set of final picture comparison areas and corresponding final model comparison areas;
• for each final model comparison area, identifying desired mounting parts located therein and searching for mounted parts in the corresponding final picture comparison area that match said desired mounting parts;
• and
• identifying the desired mounting parts, which have no matching mounted part in the final picture comparison areas, as missing from the assembled structure.