Design and Analysis of a Low-Coupling Parallel Piezoelectric Nanopositioner Based on a Pseudo-Symmetric Structure

To meet the increasing demands for large stroke and low cross-axis coupling in precision instruments such as atomic force microscopy (AFM), a low-coupling parallel piezoelectric nanopositioning stage based on a pseudo-symmetric guiding mechanism is proposed. By integrating a compact flexure-based lever amplification mechanism with a parallel pseudo-symmetric guiding structure, the design achieves effective suppression of cross-axis coupling while maintaining a relatively large motion range. A static model is established based on Castigliano's second theorem, and electromechanical coupled finite element analysis is performed to evaluate the output characteristics and dynamic behavior. A prototype is fabricated and experimentally validated. The results demonstrate that the stage achieves a travel range of 121 μm × 122 μm, a cross-axis coupling error ratio of 1.1%, resolutions of 7 nm and 5 nm along the X- and Y-axes, respectively, and a first natural frequency of 476 Hz. The proposed design provides a feasible approach for achieving a balance among large stroke, low coupling, and high dynamic performance in piezoelectric nanopositioning systems.