Stiffness Analysis of a Planar 3-RPS Parallel Manipulator

This paper studied the stiffness model and characteristics of a planar 3-RPS PM with 3-DOF. The 6 × 6 form stiffness matrix of the planar 3-RPS PM is derived with both active and constrained wrenches considered. To characteristic the stiffness of the planer 3-RPS PM, two decomposition methods including the eigenscrew decomposition and the principle axes decomposition are applied to the stiffness matrix. The stiffness matrix decomposition provides a physical interpretation and allows the identification of the compliant axes of the planar 3-RPS PM.