A systematic approach to stiffness analysis of parallel mechanisms

A systematic approach to compute total stiffness of parallel manipulators is proposed. Link stiffness and joint stiffness can be calculated simultaneously. Stiffness of passive joint (joint without actuator) is temporally assumed as nonzero variable in the procedure and infinite stiffness can be treated. A simple parallel manipulator is used as an example to illustrate the process and its correctness. Then validity of the proposed approach is confirmed by comparing to FEA and conventional joint stiffness method. The total link compliance (inverses of total stiffness) calculated by the developed approach and its counterpart obtained by FEA model are very close. The total joint stiffness computed by the developed approach and its correspondence derived from conventional joint stiffness method are totally the same. Stiffness performance of parallel force redundancy mechanisms is evaluated. These results indicate that this scheme is feasible and effective.