Accuracy Assessment of Articulated Industrial Robots using the Extended- and the Loaded-Double-Ball-Bar

Abstract

This research paper outlines the methodology and application of geometric and static accuracy assessment of articulated industrial robots using the Extended-Double-Ball-Bar as well as the Loaded-Double-Ball-Bar. In a first experiment, the EDBB is used to assess the geometric accuracy of a Comau NJ-130 robot. Advanced measuring trajectories are investigated that regard poses, which maximize the error influences of individual robot components. The developed error-sensitive trajectories are validated in experimental studies and compared to the circular trajectories according to ISO-230-4. Next, the Loaded-Double-Ball-Bar is used to assess an ABB IRB6700 manipulator under quasi-static loads of up to 600 Newton using circular testing according to ISO-230-4 and stiffness is identified. Then, the stiffness is used to perform a reverse calculation to identify the kinematic errors on the path deviations. The concept is validated in a case study of quasi-static loaded circular testing using the Loaded-Double-Ball-Bar compared to a Leica-AT960 laser tracker.