Magnetically Levitated Parallel Actuated Dual-Stage (Maglev-PAD) System for Six-Axis Precision Positioning

This paper presents a magnetically levitated parallel actuated dual-stage (maglev-PAD) motion system for six-axis precision positioning. This dual-stage motion system consists of a six-degrees-of-freedom (6-DOF) maglev primary stage for coarse positioning and a 2-DOF planar motion flexure-based secondary stage for fine positioning. Its coarse-fine positioning is realized through a parallel actuation concept. Unlike the conventional designs, the secondary stage in this dual-stage system is serially connected to the primary stage via the flexure hinges while the actuation coils are laid underneath the primary and secondary stages. This design concept largely minimized the size and weight of the levitated platform, thus improving the dynamic characteristics. Furthermore, the primary and secondary stages are truly contactless and most importantly cableless since no power cable is attached to the secondary stage. Design, analysis, and modeling of the Maglev-PAD motion system are presented in this paper. A prototype was developed and demonstrated that the proposed concept largely improves the static positioning errors and significantly compensates the dynamic tracking errors beyond the performance of the primary maglev stage.