Development of nonresonant ultrasonic motor with sub-nanometer resolution

Precise positioning, which is the base technology for ultra-precise treatments, is highly essential in semiconductor LSI circuits, bio-cells, molecular sensors, and quantum devices. Conflicting performances, high-speed, long-stroke, and high-resolution have been achieved by using die nonresonant ultrasonic motor (NRUSM) controlled under the piezoelectric effect. One of the notable features of the NRUSM is do the frequency of the driving voltage can be varied in a wide range, which means the motion control of the NRUSM can be done by both the amplitude and frequency The maximum stage feed velocity is 140 mm/s with average acceleration of 2200 mm/s/sup 2/ in the 100 mm stroke under open-loop control. 100 nm step response with /spl plusmn/0.69 nm positioning accuracy is completed in 0.35 s under closed-loop control.