In-line quality control utilizing close-range photogrammetry and a CAD-model

Abstract

This paper presents an overview of a measurement system that is designed for in-line shape inspection of metal sheet components in real-time utilizing pre-calibrated close-range photogrammetry and a CAD-model. The system is currently designed to measure parts thrown out on a conveyor belt that moves at about 1ms-1 at a frequency of 0.5 Hz or less without fixturing. Detected features on the components in the camera images are used to align the CAD-model, describing the nominal shape, to the images from which required deviations are computed using photogrammetry. The measurement volume of the current system is 500x800x200mm3 and absolute measurements are performed with an accuracy in the order of 0.1 mm. The in-line functionalities of the system have been verified at several real production sites in Sweden. In this paper, the basic components of the system are described together with a few results from real tests.