A novel measurement and analysis technique for inspection of sheet metal parts based on statistics

This paper presents the practical implementation of a novel shape measurement and analysis scheme for automatic quality inspection of sheet metal parts with large and complicated curved surfaces used widely for manufacturing applications base on statistics. In the proposed technique, the online measurement system (OLMS) developed with improved accuracy, flexibility and advanced measuring efficiency advantages, and the shape error analysis are used to assure quality and to reduce manufacturing costs and rework. The proposed shape error analysis technique first uses a statistical method to determine the number of test-points with suitable sample size. Then, the technique uses centroid-based matching and flexible transversal matching to perform the geometrical adjustment, following a report on detected shape errors. Experimental results showed satisfactory performances of the proposed shape measurement and analysis technique in terms of speed, accuracy and reliability in manufacturing processes.