Quasi-static loaded circular testing of serial articulated industrial manipulators

This research outlines the methodology and application of quasi-static loaded circular testing on serial articulated industrial robots using the Loaded Double Ball Bar (LDBB). The article focuses on measuring the quasi-static path accuracy and repeatability of industrial manipulators to evaluate their performance in industrial contact applications such as trimming, grinding, or deburring. The manipulator is measured under quasi-static loads of 100, 350, 500, and 600N using circular testing following the guidelines of ISO 230-4. The data can be used to discuss core aspects of process planning with industrial manipulators such as workpiece placement, optimal robot pose selection for dexterity as well as stiffness optimization. The article contains a case study of quasi-static loaded circular testing of a mid-size articulated industrial robot from ABB using the LDBB and a Leica AT960 laser tracker for validation. At a load of 600N the path accuracy for both Clock-Wise (CW) and Counter Clock-Wise (CCW) were 2:4 mm, measured with the LDBB, compared to 2:9 mm, measured with the AT960. Finally, the paper ends with a discussion about the opportunities and challenges for the implementation of loaded circular testing for elasto-geometrical calibration of industrial manipulators.