Robot operation monitoring for collision avoidance by image sequence analysis

摘要

Safety is an important issue of industrial automation. In this study, a new approach to monitoring multiple operating robot manipulators for on-line collision avoidance by image sequence analysis is proposed. The features used are line segments and each two-dimensional (2D) projective robot shape forms a polygon. In the monitoring process, multiple image sequences about the operating robots are taken from various views using fixed video cameras. For each view, three image frames taken from three recent frames (current and previous two frames) are used to predict each robot shape location in the predicted space, i.e. in the next frame. Three-dimensional (3D) robot operation monitoring for collision avoidance is decomposed into some collision checkings performed in multiple 2D image sequences. In the predicted space, if two robot shapes overlap mutually or the minimal distance between two robot shapes is smaller than a thresholding value in all camera views, then the robots are forced to halt for safety; otherwise, they continue to operate. To speed up the monitoring system, line segment correspondence between two consecutive images from a camera view is performed via region matching. Region matching is formulated as a bipartite matching problem. To consider the effect of robot motion, a static distance thresholding Ts and a dynamic distance thresholding Td are used to check if any two robot shapes are “safe” from a view. Some experimental results show the feasibility of the proposed approaches.