Multirate PWM Control of Precision Stage for Ultrahigh-Speed Nanoscale Positioning

Motion control techniques are employed for nanoscale positioning in industrial equipment such as numerical control (NC) machine tools and exposure systems. The advanced motion control techniques are based on precise current control. However, speeding up the precise current response causes a serious limitation owing to the carrier period of the inverter. In addition, the position response has to be slower than the current response. In a previous paper, we designed and fabricated an experimental precision stage, achieving novel ultrahigh-speed nanoscale positioning based on multirate pulse width modulation (PWM) control. However, it was difficult to achieve faster and more precise positioning because of the resonance modes of the stage. In this paper, we propose a multirate PWM control in which the resonance mode is considered. Simulations and experiments are performed to demonstrate the advantages of the proposed method.