Micro Geared Ultrasonic Motor

Tomoaki Mashimo, Takateru Urakubo, Yukiharu Shimizu

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


We propose a micro geared ultrasonic motor, the smallest set of a micro ultrasonic motor and micro planetary gear. Our micro ultrasonic motor is one of the most powerful motors in one-millimeter-scale motors. The use of a micro planetary gear amplifies the motor torque to several tens of times and the geared motor enables a high torque density that was unachievable by existing miniature motors. The goal of this paper is to analyze the dynamic characteristic of the micro geared ultrasonic motor with a mathematical model and confirm the torque amplification experimentally using a micro planetary gear prototype. To build the microgear components, we employ a micro-injection molding process using metallic glass, a relatively new material, with a low melting temperature. The micro planetary gear assembly with a diameter of 2 mm, a length of 5.9 mm, and a gear ratio of 256 is built and connected to the micro ultrasonic motor. The micro geared ultrasonic motor demonstrates a continuous torque of 0.4 mN and a peak torque of 1 mN m in the load lifting experiments.

Original languageEnglish
Pages (from-to)781-787
Number of pages7
JournalIEEE/ASME Transactions on Mechatronics
Issue number2
Publication statusPublished - Apr 2018
Externally publishedYes


  • Micro actuators
  • piezoelectricity
  • planetary gear
  • transmission mechanism

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Computer Science Applications
  • Electrical and Electronic Engineering


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