Elastostatics of a Full-Mobility PKM with Flexible Links

The subject of this paper is the elastostatics of a novel three-limb, full-mobility parallel-kinematics machine (PKM) with flexible links, dubbed the SDelta robot. Due to the inherent flexibility of the light-weight limb rods under fast operations, they are modeled as identical linearly elastic beams. The moving platform of the PKM is assumed to be elastically attached to the base platform via a six-dof generalized spring. Because of the symmetric design of the SDelta robot, the constant generalized stiffness matrix becomes isotropic. Moreover, the posture-dependent Cartesian stiffness matrix is derived. Based on the preliminary design of a prototype at the desktop scale, its stiffness matrix is numerically evaluated.