On Line Model Accuracy Inspection of Model Maker Rapid Prototyping Using Vision Technology

The principle of rapid prototyping (RP, or layer manufacturing) is to fabricate a 3D object layer by layer. Vision technology has been employed and has demonstrated its ability to measure the single-layer profile dimensions of the Model Maker (MM) RP system model. The on-line profile dimensional inspection and accuracy analysis of multiple layers is presented in this paper. The image-processing algorithms, developed to measure the layer profile dimensions, were adapted to process the captured profiled image of multiple layers, layer by layer. Hence, the layer profile dimensions of multiple layers were inspected on-line and layer by layer. The problems of vision inspection associated with colour mixing of multiple layers are addressed. A colour CCD camera was employed to resolve the colour mixture problem, but it is too expensive and too much memory is required. A new image difference algorithm was proposed to solve the problem of colour reflected from adjacent layers. The results demonstrate the promise of on-line profile dimensions inspection and accuracy analysis using vision technology.