New magnetically levitated precision positioning stage

To improve the stability of the magnetic levitation system, a novel scheme of six-degree of freedom magnetically levitated precision positioning stage is designed, where 12 air core electromagnetic coils and 36 permanent magnets are employed as the stator and mover respectively, and the levitation and linear drive parts of the stage are separated, thus the coupling between them is minimized and the nonlinearity due to the ferromagnetism is avoided. Based on Lorentz law, some parameters, including the permanent magnets length, currents and levitation displacement, which may affect the stability, are analyzed to determine the equilibrium position. A mathematical model in levitation direction is established and the dynamic response is simulated. The results show that the stage enable to work stably under the conditions with 2 A current and 0.5 mm levitation height. The stage is especially suitable for semiconductor photolithography requiring ultra precision positioning and super cleanness.