Effects of joint dynamics on the dynamic manipulability of geared robot manipulators

Abstract

Information obtained through the analysis of dynamic manipulability can be useful in the design and control of robotic manipulators. In this paper, we investigate the influences of the joint drive systems on the dynamic manipulability, with special attention to the effects of gear reduction ratios. In order to reflect this influence, a new form of the dynamic manipulability ellipsoid is developed, which includes the gear reduction ratios, and a modified formula is derived for the dynamic manipulability measure. This formula indicates that joint drive dynamics can significantly influence the dynamic manipulability of a robot. The most important effect is that changing the gear reduction ratios modifies the nature of the dynamic manipulability distribution throughout the workspace of the manipulator. Examples of a two-link planar arm and a PUMA 560 robot are presented to illustrate the results.