Kinetostatic Modeling and Performance Analysis of a Symmetric Redundant-Actuated 4-PSS Compliant Parallel...

A symmetric redundant-actuated 4-PSS compliant parallel micro-motion mechanism is proposed to meet the high requirements for stiffness and motion precision in micro-nano manipulation. First, the screw theory is employed to confirm that the mechanism possesses spatial three translational (3T) degrees of freedom along the X, Y and Z axes. On this basis, the global compliance model of the mechanism is constructed by combining the compliance matrix method with coordinate transformation technology, and the kinetostatic model reflecting the mapping relationship between input force/displacement and output displacement is further derived. The finite element analysis (FEA) is used to verify the kinetostatic model, and the results show that under the predefined spiral trajectory, the maximum absolute error between the theoretical calculation and the simulation result is less than 6 × 10^-7 m, which proves the high accuracy of the established model. Moreover, a comprehensive performance analysis of the 4-PSS mechanism is carried out from the perspectives of output stiffness and parasitic motion, with the traditional 3-PSS compliant parallel mechanism as the reference. The comparative results indicate that within the specified 50 μm cubic workspace, the 4-PSS mechanism achieves a 33.3% improvement in output stiffness and a 28.15% reduction in the maximum parasitic displacement compared with the 3-PSS mechanism, while maintaining excellent global stiffness isotropy (GSI). Sensitivity analysis confirms the robustness of these advantages against manufacturing variations, and the workspace-to-footprint ratio remains unchanged. This research verifies that the introduction of symmetric redundant actuation branch chains can effectively enhance the comprehensive performance of compliant parallel micro-motion mechanisms and provide engineering references for the redundant design and performance optimization of high-precision compliant parallel mechanisms in the field of micro-nano manipulation.