In manufacturing processes, many robots are used to operate, assemble, and handle the parts and materials. However, the recognition ability of these robots is not highly flexible for different shapes of parts. Recently, as the life cycle of products becomes shorter, robots should be required to handle more different shapes of parts. To correspond to this requirement, recognition ability by image processing should be continuously increased. In this paper, we propose an assembly robot system with high recognition ability attained by combining three-dimensional computer-aided design information with image processing. This system is composed of two robots, six cameras, and four computers. One camera (upper camera) is set at the upper side, and the other three cameras (side cameras) at the contour of the recognition area. On the robot, one camera is set at the hand (hand camera). The recognition ability of this system can be explained by the following three functions. First, the type and direction of the parts are estimated by matching the height, which is estimated by the side cameras and images of parts to the computer-aided design information which is given a priori, since the parts are not only in singular state but also in contacting, leaning, and stacked states in the recognition area. Second, the direction of gripping is determined by the simulation of the interference between the parts and the hand of a robot using the computer-aided design information and images input from the hand camera. Finally, the position of a part being assembled by a robot and that of an assembled part are determined by the centers of the parts using two side cameras to assure the accuracy of assembly. In this system, a part can be handed from one robot to another, to change its direction and hold it.
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