Singularity analysis of a class of composite serial in-parallel robots

This paper presents the singularity analysis of a family of 14 composite serial in-parallel six degree-of-freedom robots, having a common parallel sub-mechanism. The singular configurations of this class of robots are obtained by applying line geometry methods to a single, augmented Jacobian matrix whose rows are Plucker coordinates of the lines governing the sub-mechanism motion. It is shown that this family of robots possesses three general parallel singularities that are attributed to the general complex singularity. The results were verified experimentally on a prototype of a composite serial in-parallel robot that was synthesized and constructed for use in medical applications.