Design of a compact rotational compliant stage with self-compensation for rotation center offset

Compliant rotational stages are widely used for the fine angular positioning of optical components, where rotation center stability is critical to positioning accuracy. However, conventional designs often suffer from rotation center offset. A rotational compliant mechanism with self-compensation for rotation center offset is proposed based on a two-stage lever amplification system incorporating a non-vertical connecting beam and a double-ended fixed flexure hinge. The input force transmitted to the second-stage lever is decomposed into two orthogonal components. The y direction component drives the secondary lever to generate rotational motion, whereas the x direction component produces a negative x direction displacement through the double-ended fixed flexure hinge, thereby compensating for the rotation center offset. A kinematic analysis and a compliance model are established, based on which multi-objective dimensional optimization is performed to balance the rotational output and the center-offset indicator. The optimized design is subsequently evaluated using COMSOL finite element simulations. Under a prescribed relative input displacement of 28 µm, the mechanism produces an output rotation of 3.12 mrad, with a first natural frequency of 572 Hz and a maximum center offset of 0.42 µm. The stage has overall dimensions of 51 mm × 78 mm. These numerical results indicate that the proposed configuration can reduce rotation center offset and parasitic translational coupling under the adopted idealized simulation conditions.