‘Free-form’ telescopic structures made possible with generalisation
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Researchers at Carnegie Mellon University, Pennsylvania, have enormously expanded the possibilities of telescoping to create tents, robotics and animal-shaped models that can be expanded from a tiny volume.
Traditional telescopes are straight, one shell sliding straight out from the next to increase an object’s length, such as with a ‘pirate’s telescope’. There is no reason, however, why telescoping should be restricted to long, straight objects.
After seeing a set of retractable curved claws – in the style of Wolverine of the X-Men – on display at a makers’ fair, the Carnegie Mellon researchers were inspired to explore with different types of structures capable of expanding and collapsing telescopically.
The team built a mathematical model for telescoping structures based on three requirements: each shell can be constructed from a rigid material, the telescope should be able to extend and contract without bumping into itself, and there should be no empty space left between nested shells.
Laying down these parameters led them to realise that the mechanical model of a telescope could be generalised with a model of twisting curves, each with a fixed bend (or indeed no bend at all).
“Among deployable mechanisms, telescopes are very interesting. Once you expand them, they are very flexible and you can make a lot of different shapes, all with the same telescope,” said Professor Keenan Crane, an assistant professor of computer science at Carnegie Mellon University.
“We wanted to know: what are all the possible shapes you can make from a telescoping structure?”
Their generalisation allowed them to computationally create ‘free-form’ designs for a huge variety of other telescopes. They created a prototype telescopic tent frame which expands to several times its original volume, a 3D-printed telescopic armadillo and a flexible robotic arm that can be stored in the space of a soda can.
Other possible applications could include surgical equipment capable of expanding once inserted into the body. Telescopic structures used in conjunction with other mechanisms, such as folding, could allow for even greater versatility.