Singular configurations

Abstract

This chapter introduces the notion of singular configurations. Singular configurations are particular poses of the end-effector, for which parallel robots lose their inherent infinite rigidity, and in which the end-effector will have uncontrollable degrees of freedom. We will explain why such poses should generally be avoided, and how these configurations may be characterized. We will then describe a geometric method that allows us to systematically determine the conditions for singularity, and obtain analytical relations between the parameters of the end-effector pose, corresponding to the different singularity cases. We will introduce indices that indicate how close a pose is from a singularity, and we present practical methods for determining whether a singular configuration exists within a given workspace.