Unit invariant characterization of spatial redundant manipulator singularities

A general methodology is presented for the classification of redundant spatial manipulator singular configurations. The techniques derived are shown to be independent of attitude description, measurement units, and coordinate reference frame provided by the forward kinematic equations. Conditions for null vector admissibility and escapability, i.e, reconfiguration into a nonsingular posture via self-motion, are derived through analysis of the manipulator Jacobian matrix only. A general approach to singularity classification based on perturbation techniques is presented. For one-degree-of freedom redundant manipulators, a singularity characterization procedure based on methods from dynamical systems theory is derived