Design of a Soft Composite Finger with Adjustable Joint Stiffness

Zaryab Shahid, Abigail Leah Glatman, Seok Chang Ryu

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


This article presents the design of a soft composite finger with tunable joint stiffness. The composite finger, made of two different types of silicone, uses hybrid actuation by combining tendon and pneumatic actuation schemes. Tendons control the finger shape in a prescribed direction to demonstrate discrete bending behavior due to different material moduli, similar to that of a human's finger. The pneumatic actuation changes the stiffness of joints using air chambers. The feasibility of adjustable stiffness joints is proven using both the parallel spring model and experiments that demonstrate the stiffening effect when pressurized. A set of experiments were also conducted on fingers with four different chamber shapes to observe the effect of chamber shape on stiffening and the discrete bending capability of the finger. The stiffness control can tune the structural softness of the finger, which leads to firm grasp during higher acceleration object manipulation.

Original languageEnglish
Pages (from-to)722-732
Number of pages11
JournalSoft Robotics
Issue number6
StatePublished - Dec 2019

Bibliographical note

Publisher Copyright:
© Copyright 2019, Mary Ann Liebert, Inc.


  • PDMS
  • firm grasp
  • high acceleration manipulation
  • hybrid actuation
  • tunable joint stiffness


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