Easy-to-make sponge device helps stiff robots grasp gently

The novel device imitates the variable stiffness of a human touch.
Loukia Papadopoulos
A close-up of a sponge.jpg
A close-up of a sponge.


Researchers from the University of Bristol have found that an easy-to-make sponge-jamming device can help stiff robots tackle delicate objects. The novel device imitates the variable stiffness of a human touch.

This is according to a press release by the institution published on Wednesday.

Currently, robots can do many things but they are too rigid to hold an egg easily and safely without breaking it. Variable-stiffness devices consisting of a silicone sponge could provide a solution. 

Lead author of the new study Tianqi Yue from Bristol's Department of Engineering Mathematics explained: "Stiffness, also known as softness, is important in contact scenarios.

"Robotic arms are too rigid so they cannot make such a soft human-like grasp on delicate objects, for example, an egg.

"What makes humans different from robotic arms is that we have soft tissues enclosing rigid bones, which act as a natural mitigating mechanism.

"In this paper, we managed to develop a soft device with variable stiffness, to be mounted on the end robotic arm for making the robot-object contact safe."

Cheap and readily-available

Best of all, the new device consists of a silicone sponge that is a cheap and easy-to-fabricate material. Once squeezed, the sponge stiffens which is why it can be transformed into a variable-stiffness device.

"We managed to use a sponge to make a cheap and nimble but effective device that can help robots achieve soft contact with objects. The great potential comes from its low cost and light weight,” Yue added in the statement.

"We believe this silicone-sponge based variable-stiffness device will provide a novel solution in industry and healthcare, for example, tunable-stiffness requirement on robotic polishing and ultrasound imaging."

The team is now focused on giving the device variable stiffness in multiple directions, including rotation. The device has applications in industrial robotics including in gripping jellies, eggs and other fragile substances. It can also be used in service robots to make human-robot interaction safer and more comfortable 

Scientists have been long trying to give robots the sense of touch. Just last week Stanford professor Zhenan Bao and his team announced the invention of a multi-layer self-healing synthetic electronic skin that mimics the real thing allowing robots to feel like humans.

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