Equivalent Magnetic Network-Based Multiphysics Optimization of a Normal-Stressed Millimeter-Range Nanopositioning Stage

Establishing efficient and accurate analytical models for the normal-stressed electromagnetic actuators (NSEAs) is crucial for optimizing the magnetic stages to achieve desired working performance. To overcome the challenges of existing electromagnetic models for NSEAs, a parametric equivalent magnetic network model with adaptive meshes was developed for the designed NSEA stage, which fully included the nonlinear flux leakage, magnetic saturation, and material nonlinearity. Thereafter, by combining a mechanical model for the compliant bearing, an electromagnetic-mechanical coupling optimization method with multiple constraints was proposed for the stage to achieve a millimeter-range motion with a maximized natural frequency. As for the optimized stage, the electromagnetic actuation and bearing performance were then comprehensively verified by finite element analysis. The optimized prototype was tested to have a stroke of around +/- 1016.2 mu m and a resonant frequency of 308 Hz, which agreed well with the theoretical design. Compared with the state-ofthe-art stages with similar strokes, the developed normalstressed electromagnetic stage has a much higher natural frequency.