In this article, the authors reproduce gloss unevenness on a paper surface by expanding the Torrance-Sparrow model, which is based on the measurement and analysis of mesoscopic facets on paper. As the conventional Torrance-Sparrow model only considers macroscopic and microscopic facets, the authors expand the model to be able to consider mesoscopic facets. The normal vectors of mesoscopic facets on a paper surface were measured by using a collimator lens system with a small pinhole aperture, and the authors obtained the normal vector map by moving the stage for the paper. Gloss unevenness was reproduced by generating the same probability distribution as the measured distribution of the normal vectors. As a result, the authors succeeded in reproducing gloss unevenness using an expanded Torrance-Sparrow model.

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Robotic welding has been the biggest use in many industry. It is important to control weld robots without weld spatter for small size target. To prevent flying weld spatter, the precursory phenomenon of weld spatter must be detected, and power source of robotic welding must be controlled to reduce before weld spatter occurs. This study aimed to propose a control system to prevent the occurrence of flying weld spatter during laser or gas tungsten arc (GTA) welding process in real-time. Because the strategy involves detecting the precursory phenomenon at high-speed, we simplified the recognition system as much as possible. The system consists of a lighting system to illuminate the weld pool, a high-speed camera and an FPGA board. The control algorithm of this system used image data information for a histogram. We analyzed the images from the high-speed camera during welding. Our analysis found that, just before the weld spatter is generated, very bright pixels temporarily and abnormally increased as the precursory phenomenon. According to the proposed system, it is possible to prevent the occurrence of weld spattering in real time during the welding process. This integration of visual feedback in a robotic welding system enhances the quality of the weld work.

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