Measuring Quality of Surfaces By A Visual Sensing System

Abstract Significant attributes of timber-surfaces are to be recognized by visual inspection, while specimens are conveyed from one processing unit to the next. In order to control the manufacturing process the decision equipment must work on-line. A Visual Sensing-System should be simple and robust. Specimen is scanned by a CCD-line-camera, while it is transported across a zone of bright lighting. The CCD equipment delivers a videosignal that has been buffered in a special way, and then a microprocessor operates with only four thresholds, distributed nonlinear. With proper illumination, the system is capable to recognize such features as knots, chinks, bark, sap, insect-lodes, and (as a matter of course) deviations from outline in the image of the surface. Therefore it is possible to control a saw or - with the help of teach-in-programming - to select products such as parquet fillets in the order of their quality-classes. In this way it becomes possible to run highly productive processing-complexes fully automatised.