A piezo-driven 2-DOF compliant micropositioning stage with remote center of motion

Micro-/nanomanipulator with remote-center-of-motion (RCM) plays a key role in precision out-of-plane aligning since it can eliminate the harmful lateral displacement generated at the output platform. This paper presents the design, modeling and test of a novel piezo-driven 2-degree-of-freedom (2-DOF) flexure-based micropositioning stage with RCM characteristic. The stage is articulated from a 3-legged parallel kinematic configuration, where the 2-DOF RCM is ensured by three improved parallelogram RCM modules (PRMs). Flexure-hinge based structures and piezoelectric stack actuators (PSAs) are adopted in the design in view of their superiorities in precision positioning applications. The analytical models predicting kinematics, stiffness, and workspace of the stage have been established and evaluated by finite element analysis (FEA). A prototype of the stage is fabricated, with which a series of experiments are carried out. The experimental results indicate that the developed RCM stage can achieve a workspace of 1030 micro-rad × 920 micro-rad (μrad) about its two working axes with a resolution of 1 μrad. Besides, the maximum center shift of the RCM point tested by an optical microscope is observed to be less than 1.3 μm, which validates the effectiveness of the proposed scheme.