Process Monitoring using Three Dimensional Computed Tomography and Automatic Image Processing

In this paper we present a fast three dimensional computed tomography system in combination with automatic 3d image processing, which gathers necessary information for production control of sugar beet seed. We outline the design of the inspection system and the three dimensional image processing. Within one hour the geometrical parameters of more than 1000 seeds (about 3-4 mm diameter) are measured with accuracy better than 0.1 mm. Introduction In the last five years three dimensional computed tomography (3d-CT) is more frequently used in automotive industry for failure analysis and for development of new products. In plastic injection moulding industry 3d-CT is successfully applied to measure geometrical parameters or to characterise the quality of the casting part in combination with automatic 3d image processing [1]. The production of commercial seed requires information about the morphological structure especially in case of sugar beet seed because of the variable anatomy of the seed. The process parameter depends on different geometrical parameter for instant to equalize different thickness of the paring to the filed emergence behaviour. The 3d structure can be fast determined by 3d-CT. In contrary to technical products the shape of biological products is irregular. In this case it is difficult to determine relevant measuring quantities by automatic image processing. 1 Production steps of sugar beet seed Sugar beet seed is a fruit with a wooden shell, pericarp and paring and the embryo in the cavity. The thickness of pericarp and paring varies strongly on the condition of breeding. Figure 1 shows the 3d reconstruction of a sugar beet seed(green ware) with about 10 μm voxel size. The 3d view shows the embryo within the cavity, the wooden paring and the sponge like pericarp. The diameter of the greenware varies between 1,5 and 4,5 mm. During the production process the seed is polished removing pericarp and reducing thickness of paring. Fully filled seed is separated from half filled and empty seed using gravitation-counterflow sizer; polished seed is sieved to different calibre. ECNDT 2006 We.3.7.1