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The team at the University of Bristol, based at the Bristol Robotics Laboratory, used flexible piping to build the tetrahedron shaped robot, known as Tetraflex. Designed to move through small gaps or over challenging terrain, it can also reportedly ‘encapsulate’ fragile objects such as eggs, transporting them safely within its soft body.
A paper by the researchers, published in IEEE Robotics and Automation Letters, showed that the Tetraflex robot is capable of locomoting in multiple different ways. “This makes the robot potentially useful for mobility in challenging or confined environments such as navigating rubble to reach survivors of an earthquake, performing oil rig inspections or even exploring other planets,” a Bristol announcement said.
The device’s transport capability adds another dimension to potential applications, the researchers said. It could be used to pick up and transport payloads from otherwise inaccessible locations for example, helping with ecological surveys or in nuclear decommissioning.
Lead author Peter Wharton, from Bristol’s School of Engineering Mathematics and Technology, said: “The robot is composed of soft struts connected by rigid nodes. Each strut is formed of an airtight rubber bellow, and the length of the strut can be controlled by varying the air pressure within the bellow.
“Higher pressures cause the bellow to extend, and lower pressures cause it to contract. By controlling the pressure in each bellow simultaneously we can control the robot shape and size change.
“After this, it was simply a matter of experimenting with different patterns of shape change that would generate useful motions, such as rolling or crawling along a surface.”
The soft struts can change length freely and independently. By changing the lengths of the struts by the right amount and in the right sequence, the team can generate multiple different types of movement, such as rolling or crawling. They can also change the size of the robot, and even envelop and transport payloads.
Wharton said: “I would say these capabilities are a natural consequence of working with such a versatile structure, and we hope that other interesting capabilities can be developed in the future.
“The most exciting aspect of this study for me is the versatility of Tetraflex and how we might be able to use these robots to explore challenging terrain and achieve tasks in areas humans cannot access. The multiple gaits available to Tetraflex and object transport capability show this versatility well.”
The team has already enjoyed some success, coming third in the RoboSoft 2022 Locomotion Competition in Edinburgh with an earlier version, demonstrating movement over sand, through small gaps and between obstacles.
They now plan to apply machine learning algorithms, which could allow them to thoroughly explore movement patterns and optimise their current ones.
“There could be some really creative and effective ways of moving around or interacting with the environment that we haven’t yet discovered,” said Wharton.
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