Parallelisms Between Planar and Spatial Tricept-Like Parallel Robots

摘要

This paper analyzes some parallelisms between 3UPS-PU Tricept-like parallel robots and their planar version, 2RPR-PR manipulators, in terms of forward kinematics and singularities. We show that, like 2RPR-PR manipulators, all 3UPS-PU robots with flat mobile platform have special singularities for which the mobile and fixed platforms are coplanar. These special singularities turn out to be eightfold solutions of the forward kinematics, their perturbations result in double deltoids and, unlike in 2RPR-PR manipulators, encircling them does not produce nonsingular transitions.