Design and Construction of the Tuning Fork Piezoelectric Motor PACS REFERENCE: 85.50.-n Friend, James R. 1 ; Satonobu, Jun 2 ; Nakamura, Kentaro 1 ; Ueha, Sadayuki 1 ; Stutts, Daniel S. 3 1 Tokyo Institute of Technology Precision and Intelligence Laboratory 4259 Nagatsuta-cho, Midori-ku Yokohama, JAPAN 226-8503 Tel: +81 (45) 924-5052 e-mail: jamesfriend@ieee.org 2 Hiroshima University Department of Mechanical Engineering Hiroshima, JAPAN 739-8527 3 University of Missouri-Rolla Department of Mechanical and Aerospace Engineering and Engineering Mechanics Rolla, Missouri 65401 USA ABSTRACT This paper describes the design of a piezoelectric tuning-fork dual-mode motor. The motor uses a single multilayer piezoelectric element in combination with tuning fork and shearing motion to form an actuator using a single drive signal. Finite-element analysis was used in the design of the motor, and the process is described along with the selection of the device's materials and its performance. Prototypes of the actuator achieved a maximum linear no-load speed of 13 cm/s, a maximum linear force of 5.98 N, and a maximum efficiency of 25%. INTRODUCTION Piezoelectric motor systems exploit the transduction phenomenon from electrical energy input to mechanical energy output within piezoelectric materials. The solid-state construction possible with such devices coupled with their peculiar advantages over standard electromagnetic motors is constrained by their sensitivity to heat, relatively low efficiency, and short operating life [1]. However, inroads are being made on these problems, and commercially useful actuators are becoming more common. This paper presents a design that marks a small step in this process; it details the design, construction, and testing of a small single-piezoelectric element linear actuator for low-voltage applications, using, to the knowledge of the authors, previously unpublished construction techniques. Alps Corporation developed a small linear motor system [2,3] that moves a slider with decent traction and speed using either one or two multilayer piezoelectric actuators (MLPA). However, the Alps designs allow one end of the piezoelectric actuation material to be left free, allowing a significant amount of the vibration energy generated by the material to be lost. Inherent in the proposed design is the use of a single MLPA enclosed in a structure, which, when operated at the design frequencies of the actuator, uses comparatively low voltages, roughly 5 V RMS versus 100 V RMS for a 40 mm Shinsei motor. The mounting technique places the piezoelectric material in compressive prestress and makes use of both ends of the MLPA. This serves as an advantage in high-altitude, spacecraft, or Martian atmospheres where ionization of the gas surrounding the actuator could permit arcing even at modest voltages [4], and that advantage is one of the reasons for pursuing this study.