Hybrid Reluctance Actuator for High-speed Scanning with Nanometer Resolution

Abstract

For high-speed scanning with nanometer resolution, this paper proposes to use the hybrid reluctance force, which can be larger than the Lorentz force (e.g. of voice coil actuators). For the experimental demonstration, a compact scanner based on a hybrid reluctance actuator is introduced and modeled. Cascade control including current and position loops are designed and implemented, achieving a control bandwidth of 3.5 kHz and a high positioning resolution of 0.8 nm at a static point. Additionally, to track a periodic scanning trajectory, modeling-free inversion-based iterative control (IIC) is implemented as the feedforward control of the scanner. For a 400Hz triangular trajectory of 2 μm, modelingfree IIC successfully decreases the tracking error by a factor of 26 to 3.8 nm. The experiments clearly demonstrate the capability of the hybrid reluctance force for high-speed scanning with nanometer resolution.