A large-range compliant micropositioning stage with remote-center-of-motion characteristic for parallel alignment

Abstract

Micro-/nanopositioning stage with remote-center-of-motion (RCM) plays a key role in precision out-of-plane aligning since it can eliminate harmful lateral displacement generated at the output platform. This paper presents the design, modeling and test of a novel large-range flexure-based micropositioning stage with RCM characteristic. The stage is composed of an outer RCM guiding mechanism and a inner output-stiffness enhanced lever amplifier (OELA). The outer RCM guiding mechanism is constructed by a symmetric double parallelogram mechanism which can guide the stage to perform a RCM movement with high rotational precision. The inner OELA is designed to amplify the output displacement of the adopted piezoelectric stack actuator (PSA). Compared with conventional lever amplifier, the proposed OELA possesses twice the output stiffness, which makes it more appropriate for actuating the outer mechanism and therefore, a large rotational range can be obtained. Based on the pseudo-rigid-body-model (PRBM) method, the analytical models predicting kinematics, statics, and dynamics of the RCM stage have been established. Besides, the dimensional optimization is conducted in order to maximize the first resonance frequency of the stage. After that, finite element analysis is carried out to validate the established models and the prototype of the stage is fabricated for performance tests. The experimental results show that the developed RCM stage has a rotational range of 6.96 mrad while the maximum center shift of the RCM point is as low as $$9.2\,{\upmu } \text {m}$$9.2μm, which validate the effectiveness of the proposed scheme.