A classification of 3R regional manipulator singularities and geometries

3R manipulator singularities and geometries based on genericity are categorized. A recursive application of screw theory is used to generate singular configurations and provide a geometric interpretation of nongenericity. A generic manipulator classification scheme based on homotopy class is introduced. Nongeneric geometries are interpreted as bifurcations of generic geometries with respect to kinematic parameter values. Some conjectures on the classes of manipulators which can change pose without passing through a singularity are also given.