A flexure-based and motion-decoupled XYZ nano-positioning stage with a quasi-symmetric structure

Piezoelectric-driven flexure-based multi-DOF motion stages have been widely employed for nano-positioning applications, in which motion-decoupled stages have been extensively investigated in order to facilitate their motion control efforts. Asymmetric motion-decoupled stage designs are simple in configurations and structures, but would cause parasitic shifts of the moving platform. Fully-symmetric motion-decoupled stage designs can minimize parasitic shifts, but would result in complicated configurations and structures. To tackle such difficulties, a new flexure-based motion-decoupled XYZ stage with a quasi-symmetric 3-Prismatic-Prismatic-Prismatic (3-PPP) configuration is proposed in this work. By adding short flexure-based auxiliary supports to the moving platform, a compact quasi-symmetric stage design is achieved, and the parasitic shifts of the moving platform are significantly reduced. To study the kinetostatic performance of the demonstrated embodiment, an analytic stiffness model is formulated and validated by the FEA method. To achieve minimal parasitic shifts, a stiffness matching approach is proposed for the design optimization of structural parameters. A research prototype of the quasi-symmetric stage is fabricated for experimental validation. Experimental results show that the stage achieves workspace of 43.6 μm × 40.3 μm × 63.2 μm, motion resolution of 25 nm, and parasitic shifts of less than 0.94 %, which indicates that the proposed quasi-symmetric design method is effective to reduce the parasitic shifts of the flexure-based nano-positioning stages.