Large stroke electromagnetic redundant actuated six degrees-of-freedom parallel compliant micropositioning stage

Abstract

In this paper, a novel large stroke six degrees-of-freedom (6-DOF) electromagnetic redundant actuated micropositioning stage is proposed. The 6-DOF stage adopts a configuration that is composed of eight parallel driving branch chains. Each branch chain is driven by a voice coil motor and incorporates a parallelogram flexure mechanism and a decoupling mechanism for guidance and decoupling. The positioning stage is symmetrically arranged and possesses the advantages of simple structure and easy assembly. As a result, assembly errors are significantly reduced and positioning accuracy is enhanced. The decoupling mechanism uses a large stroke flexible ball joint that increases the motion range of the positioning stage and decouples the coupled motion, thereby enhancing the stability and accuracy of the stage. To evaluate the performance of the stage, static and dynamic analytical models of the 6-DOF stage are derived based on the compliance matrix method and the Lagrangian dynamic modeling method. Additionally, the accuracy of the analytical models and the static and dynamic performances of the positioning stage are verified through finite element analysis (FEA) and experimental testing. The experimental results demonstrate that the stage realizes a workspace of 2.06 mm × 2.02 mm × 3.1 mm × 23.4 mrad × 23.1 mrad × 14.9 mrad. Finally, to verify the tracking performance trajectory of the 6-DOF positioning stage, tracking experiments are performed using a controller that combines a proportional-integral controller and a notch filter.