Novel Design of a Soft Lightweight Pneumatic Continuum Robot Arm with Decoupled Variable Stiffness and Positioning

Maria Elena Giannaccini*, Chaoqun Xiang, Adham Atyabi, Theo Theodoridis, Samia Nefti-Meziani, Steve Davis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

108 Citations (Scopus)
10 Downloads (Pure)


Soft robot arms possess unique capabilities when it comes to adaptability, flexibility, and dexterity. In addition, soft systems that are pneumatically actuated can claim high power-to-weight ratio. One of the main drawbacks of pneumatically actuated soft arms is that their stiffness cannot be varied independently from their end-effector position in space. The novel robot arm physical design presented in this article successfully decouples its end-effector positioning from its stiffness. An experimental characterization of this ability is coupled with a mathematical analysis. The arm combines the light weight, high payload to weight ratio and robustness of pneumatic actuation with the adaptability and versatility of variable stiffness. Light weight is a vital component of the inherent safety approach to physical human-robot interaction. To characterize the arm, a neural network analysis of the curvature of the arm for different input pressures is performed. The curvature-pressure relationship is also characterized experimentally.

Original languageEnglish
Pages (from-to)54-70
Number of pages17
JournalSoft Robotics
Issue number1
Early online date30 Oct 2017
Publication statusPublished - 1 Feb 2018

Bibliographical note

The authors acknowledge support from the EPSRC Centre for Innovative Manufacturing in Intelligent Automation, in undertaking this research work under grant reference number EP/IO33467/1. The second author is supported by the program of the China Scholarships Council (No. 201406080054). No competing financial interests exist. The authors are grateful to A. Baker, M. Irshaidat, M. Sharba, and Dr. H. Hauser for their help with hardware and software components. In accordance with EPSRC and University of Salford rules, the data relative to the research work presented are stored on Figshare, identified by the DOI: 10.17866/rd.salford.5139973. The work described in the article by Giannaccini was conducted while she was employed at Salford University. She is now employed by Bristol University.


  • physical human-robot interaction
  • pneumatic actuators
  • soft robot arm
  • variable stiffness


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