A smooth impact rotation motor was fabricated and successfully operatedusing a torsional piezo actuator. Yoshida et al. [1] reported a lineartype smooth impact motor in 1997. This linear motor demonstrated a highoutput force and a long stroke. A superior feature of the smooth impactdrive is a high positioning resolution compared with an impact drive [2].The positioning resolution of SIDM (smooth impact drive mechanism) is equal to the piezo displacement. The reported positioning resolution of the linear type was5 nm.
Our rotation motor utilized a torsional actuator containing multi-layeredpiezoelectric material. The torsional actuator was cylindrical in shape withan outer diameter of 15 mm, an inner diameter of 10 mm, and a length of11 mm.
Torsional vibration performance was measured with a laser Dopplervibrometer. The obtained torsional displacement agreed with the calculatedvalues and was sufficient to drive a rotor. The rotor was operated with asaw-shaped input voltage (180 V; 8 kHz). The revolution direction wasreversible. The maximum revolution speed was 27 rpm, and the maximum outputtorque was 56 gfcm. In general, smooth-impact drives do not show highefficiency; however, the level of efficiency of our results (max., 0.045%)could be increased by improving the contact surface material. In addition,we are studying quantitative consideration, for example, about the optimumpre-load or frictional force.
© 1999, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.