A large-range compliant remote center of motion stage with input/output decoupling

This paper presents the concept design of a large-range compliant remote center of motion (RCM) stage with input/output decoupling. The developed RCM stage can achieve 2-degree-of-freedom (2-DOF) rotation motion without generating extra lateral displacement in precision parallel alignment process. The RCM characteristic is realized based on parallelogram-based RCM module (PRM). The proposed stage is featured with input/output decoupling based on the novel designed structure. The input decoupling is realized by the employ of two up-down stacked arranged input stages. The output decoupling is realized by the orthogonal arrangement of two 1-DOF RCM stages combining the wire flexure hinges. The rectangular flexure hinge and the voice coil motor (VCM) are utilized to generate large-range rotation motion considering their large compliance and large stroke, respectively. The design, theoretical analysis and experimental test of the stage are presented. Based on pseudo-rigid-body-model (PRBM) method and compliance matrix method, the theoretical analysis is conducted to evaluate the kinematics, statics, dynamics and workspace of the RCM stage. Besides, finite element analysis (FEA) is conducted to validate the established models and an experimental system of the stage is set up for performance tests. The experimental results show that the proposed RCM stage can achieve a workspace of 14.4 mrad × 16.6 mrad in its two working directions with a resolution of 15.1 μrad. Moreover, the maximum coupling output angles about the two axes is less than 0.1 mrad and 0.16 mrad, which demonstrate the decoupling property of the developed stage.