Papers by Keyword: Nanometer Positioning

Abstract: New holding mechanism is proposed to improve the positioning capability of ultrasonic linear motor based on previous researches proposed by the authors. Through the previous holding mechanism using a resonance system, the remarkable operating stability and controllability at high-power driving were achieved. However, when higher power is demanded, big noise in supporting parts of a resonance system is generated and these parts could be damaged and worn due to the discordance of a resonance frequency between a transducer and supporting horns. Also the coupling problem of two vibration modes remains because of using a half wavelength. This research proposes a new design of ultrasonic motor with three supporting points in one vibrator for high stiffness support and discusses the solution about the coupling effect and the nano-level positioning capability. Finally, a maximum driving mechanical force and the positioning accuracy were achieved over 75 N and 100 nm through this mechanism. Moreover, the efficiency of motor was 35% when the trust force was 52 N and the velocity was 0.27 m/s.

Abstract: This paper deals with nanometer positioning in the presence of friction. The object studied is a ball-screw-driven and linear-ball-guide-supported table system. For this system, the friction dominates the resulting performance for micro-motion and the system exhibits microdynamic characteristic which is rather different from macrodynamics. Inherently a controller with high loop-gain is needed to suppress the effect of friction. A PID controller is designed for the table system for step height smaller than 10μm. Experiment and simulation results indicate that the PID controller can provide a sufficiently high-loop gain and effect of friction is suppressed. In point-to-point(PTP) positioning for step heights from 10μm down to 10nm, the positioning error is within ±2 nm and the response dynamics is satisfactory.

Abstract: This paper deals with nanometer positioning in the presence of friction. The object researched is a ball-screw-driven and linear-ball-guide-supported table system. For such system, models that do not account for friction can only be applicable to describe the macrodynamic behavior which is significantly different from the microdynamic one. A PID controller is designed with high-loop gain to suppress the effect of friction. The controller parameters are calculated by pole placement according to macrodynamics, no identification of friction and friction model are necessary. Experiment and simulation results indicate that nanometer positioning can be realized in this system by the controller. In point-to-point (PTP) positioning for step heights from 0.1μm to 1mm, the positioning error is within ±5 nm and the response characteristics are satisfactory.