A small linear ultrasonic motor utilizing longitudinal and bending modes of a piezoelectric tube

Abstract

A small linear ultrasonic motor which consists of a piezoelectric ceramic Pb(Zr,Ti)O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (PZT) tube (outside diameter 5 mm, inside diameter 3 mm, length 15 mm, acts as stator) and a shaft (acts as slider) has been developed. The outer surface electrode of the PZT tube is divided into 4 parts to excite longitudinal-bending (L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) modes, which could be then used to produce linear motion. The motor shows a high power (force) density. It has a no-load speed of 0.14 m/s, a stall force of 0.3 N, and a maximum output power of 9.3 mW under an applied voltage of 100 Vpp. The method for further improving the performance has been discussed. The proposed motor can be further miniaturized because of its simple structure, and it has potential to be applied to medical microrobots, endoscopes, or micro laparoscopic devices, etc.