Workspace analysis of realistic elbow and dual-elbow robot manipulators

The geometry of the robotic structure directly influences the positional and orientational capabilities of a manipulator. Among the existing robot geometries, the ideal elbow and dual-elbow manipulators are known to provide the maximum reachable and dextrous workspaces for a given total link length. Despite the fact that the ideal dual-elbow manipulators share the basic properties of the ideal-elbow manipulators, they have received scant attention in the literature. In a companion paper [Mech. Mach. Theory 28, 357-373 (1993)], the ideal elbow and dual-elbow geometries have been thoroughly studied. In this paper, realistic elbow and dual-elbow geometries, incorporating designed deviations from the ideal case and unavoidable manufacturing errors, are considered. It is shown that practical dual-elbow robots are superior in terms of reachability and dexterity, especially for applications that require a relatively small tool length.