Tornado: Power Assist Suit to Assist Twisting Motion of Lower Back

Motoki Hirose, Sota Shimizu, Rikuta Mazaki

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In this paper, the authors develop a 2-DOF power assist suit (PAS), namely Tornado. Our developed PAS assists power for twisting motions in addition to lifting and lowering motions in environments of agriculture, fishery, factory, and so on. Tornado PAS not only assists power to some motions but also protects our lower back by limiting high-risk motions which causes lower back injuries. The authors apply a differential gear box mechanism to achieve 2-DOF power assist. The prototype of 2-DOF PAS is implemented by comprising two DC motor, two rotary encoders, two current control motor drivers, 2-channel encoder counter board, 2-channel DIO board, battery, and Raspi4 controller installing Linux OS. Although Tornado PAS assists power according to an external force, our system do not use any force sensor. We apply a disturbance observer (DOB) to estimate such an external force. Thus, Tornado is characterized as follows: (1) a unique mechanism using a differential gear box, (2) not only power assist but also prohibiting dangerous motions by computer control, and (3) force sensorless power, i.e., force, assist. In this paper, the authors model Tornado, and establish equation of motion in order to simulate various types of control methods and observers. We experiment power assist of twisting motions based on some position tracking control. Results this control and values estimated using DOB are discussed and evaluated for effective power assist for twisting motion.

Original languageEnglish
Title of host publicationIECON 2022 - 48th Annual Conference of the IEEE Industrial Electronics Society
PublisherIEEE Computer Society
ISBN (Electronic)9781665480253
Publication statusPublished - 2022
Event48th Annual Conference of the IEEE Industrial Electronics Society, IECON 2022 - Brussels, Belgium
Duration: 2022 Oct 172022 Oct 20

Publication series

NameIECON Proceedings (Industrial Electronics Conference)


Conference48th Annual Conference of the IEEE Industrial Electronics Society, IECON 2022


  • 2-DOF
  • differential gear
  • external force estimation
  • power assist suit
  • twisting lower back support
  • wearable robot suit

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering


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