Integration of 3D Stereo Vision Measurements in Industrial Robot Applications

Three dimensional (3D) vision systems are more and more used in recent industrial robot applications for enhancing robot flexibility and intelligence. This paper presents a method of integrating 3D binocular stereo vision systems into industrial robot systems. Examples are used to illustrate the developed method and its implementation including vision system setup and calibration, robot hand-eye integration, and vision measurement analysis. The results show that a 3D stereo vision system is able to guide an industrial robot to manipulate a 3D object through accurate vision measurements and integrated robot programming. Introduction Industrial robots are often equipped with vision systems for detecting and recognizing objects in a robot work environment. Among various vision approaches, a three-dimensional (3D) binocular stereo vision system utilizes two cameras to obtain the positioning information of a 3D object for an industrial robot. This technology is widely used in industrial robot applications due to the simple setup of lighting conditions and the efficient image process of the vision system. Fig. 1 shows an industrial robot workcell where the FANUC M6i robot is able to manipulate a given 3D part on the table by using the 3D measurements of the FANUC VisLOC vision system. However, in order to make the application successful, the robot programmer must correctly set up the 3D measuring functions of the vision system and integrate the precise vision measurements into the robot application programs. Industrial practice shows that vision-guided industrial robot applications not only use the technology of vision cameras, image processing, system calibration, and communication [1], [2], [3], [4], [5] but also require the robot programmer to have a solid understanding of other issues including camera positions and views, vision measurements and accuracy, reference frames and frame transformations, and robot operations and programming. This paper presents a method of integrating the measuring functions of a 3D binocular stereo vision system into an industrial robot system. The study deals with the design techniques and procedures related to vision system setup, robot hand-eye integration, and vision measurement analysis. The discussion includes the Epipolar geometry and perspective calibration used by 3D binocular vision systems, the method for unifying the coordinates of