Pitch-Up Motion Mechanism with Heat Welding by Soft Inflatable Growing Robot

Yuki Satake, Hiroyuki Ishii

Research output: Contribution to journalArticlepeer-review


Soft growing robots have recently attracted considerable interest. They are expected to operate in complicated environments leveraging their flexibility and adaptability. However, some of them are unable to maintain their bending shape without contact with an object, and some of their mechanisms are complex. In this article, we propose a novel heat welding mechanism for pitch-up motion without any support. The proposed robot uses a gusset folded tube and welds its gusset parts. The welded tube is bent, and the robot performs a pitch-up motion. In addition, we experimentally investigate the characteristics of welded bending tubes and develop a stiffness model and bending angle model. The results demonstrate that they depend on the tube diameter, weld shape, and inner pressure. We conducted experiments to evaluate the performance of the robot and confirmed that the maximum bending moment based on which the robot can maintain its bending shape increases under a higher inner pressure, and a large bending angle is obtained by continuous bending. Further, we confirmed that proposed models can adequately simulate the pitch-up motion of the robot. The proposed mechanism enables the robot to perform novel pitch-up motion and expands the application of growing robots.

Original languageEnglish
Pages (from-to)5071-5078
Number of pages8
JournalIEEE Robotics and Automation Letters
Issue number2
Publication statusPublished - 2022 Apr 1


  • Inflatable robot
  • mechatronics
  • mobile robots
  • pneumatic systems
  • soft robot materials and design

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Biomedical Engineering
  • Human-Computer Interaction
  • Mechanical Engineering
  • Computer Vision and Pattern Recognition
  • Computer Science Applications
  • Control and Optimization
  • Artificial Intelligence


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