A Novel Large-Range XY Compliant Parallel Manipulator With Enhanced Out-of-Plane Stiffness

There is an increasing need for compact large-range XY compliant parallel manipulators (CPMs). This paper deals with a novel large-range XY CPM with enhanced out-of-plane stiffness (LRXYCPMEOS). Unlike most of XY CPMs based on the 4-PP (P: prismatic) decoupled parallel mechanism, the LRXYCPMEOS is obtained from a 4-PP-E (E: planar) decoupled parallel mechanism by replacing each P joint with a planar double multibeam parallelogram module (DMBPM) and the E joint with a spatial double multibeam parallelogram module. Normalized analytical models for the LRXYCPMEOS are then presented. As a case study, an LRXYCPMEOS with a motion range 10 mm × 10 mm in both positive directions is presented in detail, covering the geometrical parameter determination, performance characteristics analysis, actuation force check, and buckling check. The analytical models are compared with the finite element analysis (FEA) models. Finally, dynamics consideration, manufacturability, out-of-plane stiffness, and result interpretation are discussed. It is shown that the LRXYCPMEOS in the case study has the following merits: large range of motion up to 20 mm × 20 mm, enhanced out-of-plane stiffness which is approximately 7.1 times larger than the associated planar XY CPM without the spatial compliant leg, and well-constrained parasitic motion with the parasitic translation along the Z-axis less than 2 × 10⁻⁴ mm, the parasitic rotation about the X-axis/Y-axis less than 2 × 10⁻⁶ rad, and the parasitic rotation about the Z-axis below 1 × 10⁻⁶ rad.