Högskolan i Skövde

We are describing a fully automatic in-line shape inspection system for controlling the shape of moving objects on a conveyor belt. The shapes of the objects are measured using a full-field optical shape measurement method based on photogrammetry. The photogrammetry system consists of four cameras, a flash, and a triggering device. When an object to be measured arrives at a given position relative to the system, the flash and cameras are synchronously triggered to capture images of the moving object.From the captured images a point-cloud representing the measured shape is created. The point-cloud is then aligned to a CAD-model, which defines the nominal shape of the measured object, using a best-fit method and a feature-based alignment method. Deviations between the point-cloud and the CAD-model are computed giving the output of the inspection process. The computational time to create a point-cloud from the captured images is about 30 seconds and the computational time for the comparison with the CAD-model is about ten milliseconds. We report on recent progress with the shape inspection system.