Stiffness optimization strategy for cable-driven redundant manipulators considering configurations and cable tension

Cable-driven Redundant manipulators(CDRMs) have demonstrated superior performance in medical, industrial, and aerospace applications due to their unique capability to navigate obstacles and flexibly capture targets in complex environments. However, these manipulators' inherent multiple degrees of freedom and cable-driven characteristics also result in relatively insufficient resistance to external forces. This study proposes a stiffness optimization strategy based on the manipulator's motion redundancy and actuation redundancy properties to address this limitation. The proposed approach systematically accounts for the combined effects of manipulator configuration and cable tensions on overall stiffness performance. Furthermore, we design a stiffness index to evaluate stiffness characteristics across different operational configurations accurately. By applying a nonlinearly constrained optimization algorithm to inverse solution optimization, the optimal stiffness configuration of the manipulator can be determined for specific tasks. This optimization ensures the manipulator's end-effector achieves the desired position and orientation and maintains enhanced stiffness. Finally, the effectiveness of the proposed stiffness optimization algorithm and the accuracy of the stiffness model are thoroughly validated through both simulation and experimental studies. Results demonstrate that the implemented optimization strategy significantly improves the CDRM's capability to withstand external disturbances.