A parallelogram-based compliant remote-center-of-motion stage for active parallel alignment.

Abstract

Parallel alignment stage with remote-center-of-motion (RCM) is of key importance in precision out-of-plane aligning since it can eliminate the harmful lateral displacement generated at the output platform. This paper presents the development of a parallelogram-based compliant RCM stage for active parallel alignment. Different from conventional parallelogram-based RCM mechanism, the proposed stage is designed with compliant mechanisms, which endows the stage with many attractive merits when used in precision micro-/nanomanipulations. A symmetric double-parallelogram mechanism (SDPM) based on flexure hinges is developed as the rotary guiding component to realize desired RCM function. Due to the geometrical constraint of the SDPM, the operating space of the stage can be easily adjusted by bending the input links without loss of rotational precision. The stage is driven by a piezoelectric actuator and its output motion is measured by non-contact displacement sensors. Based on pseudo-rigid-body simplification 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 conducted 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 1.45 mrad while the maximum center shift of the RCM point is as low as 1 μm, which validate the effectiveness of the proposed scheme.