Stiffness analysis of a hexaglide parallel loading mechanism

• We proposed a 6-DOF parallel loading mechanism.
• We deduced the total stiffness matrix of the proposed mechanism via screw theory.
• We proposed a boundary searching method for workspace volume calculation.
• A combined stiffness index is used to evaluate the machine's stiffness behavior.
• The physical meaning of the stiffness matrix is interpreted.

The stiffness characteristics of a hexaglide parallel loading machine (HPLM) are investigated in this paper. The architectural model of a HPLM is constructed and analyzed. Then the total stiffness matrix, in which the variations of the Jacobian matrix are considered, is derived based on the analysis of kinematics and statics. The workspace boundary of the HPLM is determined through a boundary searching method (BSM) and the stiffness performance over the workspace is assessed by using the extreme eigenvalues and condition number of the stiffness matrix while the influence of the architectural parameters on the stiffness behavior of the HPLM is also investigated using the same indices. Eigenscrew decomposition method is utilized to illustrate the physical interpretation of the stiffness matrix. Numerical examples follow to prove validity of the methodology.