Optimal design of a 6-DOF 4-4 parallel manipulator with uncoupled singularities

Abstract

A 6-DOF 4-4 parallel manipulator is presented. Its forward kinematics can be solved by a sequence of three trilaterations and, as a consequence, its singularities can be described in geometric terms as the degeneration of three tetrahedra. Moreover, it is shown how the proposed manipulator belongs to the family of flagged parallel manipulators. This identification is useful because the topology of the singularity locus of flagged manipulators has been fully characterized and, what is more important, the singularities of flagged manipulators correspond to uncoupled translations and/or rotations in the workspace of the manipulator. An optimization of its workspace is carried out using Sequential Quadratic Programming and a virtual prototype of the optimal result has been implemented in SolidWorks.