| Jun 07, 2023 |
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(Nanowerk News) A simple sponge has improved how robots grasp, scientists from the University of Bristol have found.
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This easy-to-make sponge-jamming device can help stiff robots handle delicate items carefully by mimicking the nuanced touch, or variable stiffness, of a human.
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Robots can skip, jump and do somersaults, but they’re too rigid to hold an egg easily. Variable-stiffness devices are potential solutions for contact compliance on hard robots to reduce damage, or for improving the load capacity of soft robots.
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This study, published at the IEEE International Conference on Robotics and Automation (ICRA) 2023 (“A Silicone-sponge-based Variable-stiffness Device”), shows that variable stiffness can be achieved by a silicone sponge.
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| Robot sponge. (Image: Tianqi Yue)
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Lead author Tianqi Yue from Bristol’s Department of Engineering Mathematics explained: “Stiffness, also known as softness, is important in contact scenarios.
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“Robotic arms are too rigid so they cannot make such a soft human-like grasp on delicate objects, for example, an egg.
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“What makes humans different from robotic arms is that we have soft tissues enclosing rigid bones, which act as a natural mitigating mechanism.
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“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.”
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Silicone sponge is a cheap and easy-to-fabricate material. It is a porous elastomer just like the cleaning sponge used in everyday tasks.
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By squeezing the sponge, the sponge stiffens which is why it can be transformed into a variable-stiffness device.
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This device could be used in industrial robots in scenarios including gripping jellies, eggs and other fragile substances. It can also be used in service robots to make human-robot interaction safer.
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Mr Yue added: “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.
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“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.”
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The team will now look at making the device achieve variable stiffness in multiple directions, including rotation.
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