Design of a 2-phase Piezoelectric Inertia Drive Type Motor

Abstract:
In this work, design and characteristics of a two-phase inertia drive type piezoelectric motor is introduced. Two identical piezoelectric multilayer actuators are placed side by side in a U-shaped base mass and framed with a thinner metal beam, which apply a preloading force to the multilayer actuators in length direction. A structure ceramic half-ball attached at the middle of the beam is in contact to a slider or a rotor. Layered flat metal springs hold the stator parallel to the slider surface and apply pressing force against it. In the stator, the two multilayer actuators are driven with mirrored sawtooth signals. As one actuator expands and the other shrinks, their synchronous deformations are converted into rotational movements of the friction coupler. When the total of 5 motors were operated at 20kHz with +/-25V, they showed the similar load characteristics, no load velocity from 16 to 18 mm/s and maximum force of more than 3N. With its dedicated controller, the motor used in a linear stage can make the smallest step of 10nm, which is the minimum value that the encoder can read.