A Silicone-sponge-based Variable-stiffness Device

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Soft devices employ variable stiffness to ensure safety and improve the robustness in the interaction between robots and objects. Material-jamming is one of the most popular approaches to design a variable-stiffness device, while the sponge-based jamming remains less explored in this field. Here we present a novel sponge-jamming variable-stiffness device (SVD). The SVD is easy-to-make and low-cost, and fabricated by an air-tight bellow enclosing a silicone sponge core. This allows easy access to the hyper-elastic response of the porous sponge whilst stiffness tuning of the device via pneumatic pressure difference, referred here as “spongejamming” effect. A detailed mathematical model of the SVD is proposed, by which the stiffness can be precisely controlled by the pressure difference applied. The stiffness of SVD can be tuned in the range of [1.55, 22.82] × 103 N/m, up to 14.7 times increase. The high stiffness is easily triggered by a low pressure difference (ΔP < 12 kPa). The SVD is a versatile and compact module, with small axial size (10 mm height) and light weight (14.3 g), making it highly suitable for integration in a wide range of robotics and industrial applications. This, in addition to its easy-to-fabricate and low-cost features, may appeal to the robotics community at large. We further detail its working principle, fabrication processes, mathematical model and automated control methods to show its versatility.
Original languageEnglish
Title of host publication2023 IEEE International Conference on Robotics and Automation (ICRA)
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages7
ISBN (Electronic)9798350323658
ISBN (Print)9798350323665
Publication statusPublished - 4 Jul 2023
Event2023 IEEE International Conference on Robotics and Automation (ICRA) - ExCel London, London, United Kingdom
Duration: 29 May 20232 Jun 2023

Publication series

NameIEEE International Conference on Robotics and Automation (ICRA)


Conference2023 IEEE International Conference on Robotics and Automation (ICRA)
Country/TerritoryUnited Kingdom
Internet address

Bibliographical note

Funding Information:
1Tianqi Yue, Tsam Lung You, Hemma Philamore, Hermes Bloomfield-Gadêlha and Jonathan Rossiter are with the Department of Engineering Mathematics and Bristol Robotics Laboratory at the University of Bristol, Bristol, BS8 1TW, UK {tianqi.yue, tl.you, hemma.philamore, hermes.gadelha, jonathan.rossiter}@bristol.ac.uk TY was funded by Chinese Scholarship Council through award 201906120027. JR was supported through EPSRC research grants EP/V062158/1, EP/T020792/1, EP/V026518/1, EP/S026096/1 and EP/R02961X/1, and by the Royal Academy of Engineering as a Chair in Emerging Technologies. Data available at: 10.5523/bris.23v6ekzwmvyop25xedxf66epjk

Publisher Copyright:
© 2023 IEEE.


  • variable stiffness


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