Analysis of the effects of manufacturing errors on the accuracy of dual-elbow and elbow manipulators

The geometry of the robotic structure directly influences the positional and orientational capabilities of a manipulator. Among the existing robot geometries, the ideal dual-elbow and elbow manipulators are the most prevalent because of their excellent posing abilities and because they provide the maximum dextrous and reachable workspaces for a given total link length. These geometries, however, are very sensitive to small manufacturing errors that distort their ideal arrangement of joint axes and impact on their accuracy. In this paper, realistic dual-elbow and elbow geometries, incorporating modeled manufacturing errors are considered and their accuracy is contrasted and compared. A set of criteria consisting of statistical measures is developed to evaluate the performance of the realistic geometries in terms of accuracy. Theoretical and experimental results demonstrate the superiority of the realistic dual-elbow geometry for the same amount of distortion and dictate its use, especially for high-precision applications.