A systematic approach to stiffness analysis of parallel mechanisms and its comparison with FEM

Stiffness is one of the key issues in designing a mechanism. On the other hand, optimizing techniques with mathematical model are required to pursue the higher acceleration by parallel mechanisms. Consequently, to find a proper way to determine the total stiffness of the mechanism is desirable. FEM (Finite Element Method) is useful, but it does not fit the optimization techniques. Therefore, a systematic approach to get the stiffness of parallel mechanisms, in which link stiffness, infinite stiffness and joint stiffness are included, is proposed. The process of this method is verified by a simple parallel manipulator. The results obtained by the proposed method are compared with the results obtained by FEM to investigate the validity of this method. Finally, this approach is applied to a 6-DOF mechanism. The result indicates that this scheme is feasible and effective.