Previously a reduced Jacobian method was used to constrain a redundant articulated arm-subassembly resulting in a complete workspace without singularities. This paper presents a purely geometric solution to the same problem, and shows that a geometric analysis of singular configurations quickly provides necessary conditions which any singularity elimination algorithm must meet. Sufficiency of the candidate algorithm is established by direct analysis.>

Adding a redundant degree of freedom to the shoulder pointing system complex of an articulated arm subassembly makes it possible to achieve a maximal workspace that is free of singularities. This paper derives a functional constraint between three of the four joints of this new type of arm, achieving a singularity-free workspace encompassing the entire reachable volume between the maximal- and minimal-reach surfaces. The large volume of dexterous workspace is verified by animation of the resulting arm design. Graphical results from the animation are presented comparing the dexterous workspace of this new arm to that of the standard nonredundant articulated arm subassembly found in the Puma manipulator.>

A study was conducted to evaluate performance of a man-machine interface system consisting of a human wearing a passive exoskeleton device. This experiment obtained some crude measures of human response characteristics treating the exoskeleton device as a complicated sensor array. A Fitt's law paradigm was used to help evaluate human performance. Fitt's law is commonly used in human performance studies and it characterizes human response in terms of speed-accuracy tradeoffs that occur as humans perform tasks. Empirical data were collected during tests involving five subjects run using five levels of speed-accuracy tasks. The results are analyzed.>