A piezoelectric motor is a type of electric motor based
upon the change in shape of a piezoelectric material when
an electric field is applied. Piezoelectric motors make use of
the converse piezoelectric effect whereby the material
produces acoustic or ultrasonic vibrations in order to
produce a linear or rotary motion. In one mechanism, the
elongation in a single plane is used to make a series of
stretches and position holds, similar to the way a caterpillar
moves.