Modeling and analysis of a 3-DOF Lorentz-force-driven planar motion stage for nanopositioning

This paper presents an approach to dynamic modeling and analysis of a 3-DOF Lorentz-force-driven planar motion stage for nanopositioning. The planar motion stage consists of a long stroke motor, a short stroke motor and a positioning platen. The long stroke motor is a linear motor, and the short stroke motor is a planar motor propelled by linear Lorentz forces and floated with high-stiffness air-bearings. The Lorentz-force-driven planar motion stage is regarded as two rigid bodies which are modeled by the Newtonian approach independently, then the relations of Lorentz forces with electric currents, magnetic fields, and displacements are obtained through electromagnetic analysis of the short stroke motor using 3-dimension finite element method. The frequency response functions of the planar motion stage in the moving directions are obtained by numerical simulation, which are in good agreement with those obtained experimentally. The positioning accuracy of the planar motion stage is also evaluated numerically and experimentally.