Displacement Sensing of an Active String Actuator by an Optical Fiber †

Weihang Tian, Shuichi Wakimoto, Kazuya Nagaoka, Yorifumi Yoshimoto, Takefumi Kanda, Daisuke Yamaguchi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


We have fabricated a string-shaped actuator called “Active string” that has high contractile displacement/force by accumulating thin pneumatic artificial muscles using the string production process. However, displacement control of the active string is challenging because general bulky and rigid displacement sensors are not suitable for the sensor element of the active string. Therefore, in this report, a flexible optical fiber sensor is combined with the active string to enable sensing of its displacement. As the active string contracts, the radius of curvature of the optical fiber decreases, and light intensity propagating in the optical fiber decreases due to bending loss. The experimental results showed that the optical fiber sensor value changed with corresponding to the displacement of the active string. It shows the possibility that it is possible to make a displacement estimation of the displacement of the active string using an optical fiber sensor.

Original languageEnglish
Article number35
JournalEngineering Proceedings
Issue number1
Publication statusPublished - 2021


  • active string actuator
  • displacement sensing
  • optical fiber sensor
  • thin artificial muscle

ASJC Scopus subject areas

  • Biomedical Engineering
  • Electrical and Electronic Engineering
  • Industrial and Manufacturing Engineering
  • Mechanical Engineering


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