Origami manufacturing has led to considerable advances in the field of foldable structures with innovative applications in robotics, aerospace, and metamaterials; however, existing origami are either load-bearing structures prone to tear and fail if overloaded, or resilient soft structures with limited load capability.

The drone can be stiff or flexible, depending on the circumstances. (©Alain Herzog/2018 EPFL)

A hybrid origami drone structure, inspired by insect wings, was developed that can be stiff or flexible, depending on the circumstances. When airborne, the structure is stiff enough to carry its own weight and withstand the thrust of the propellers. But if the drone runs into something, it becomes flexible in order to absorb the shock and therefore minimize any damage.

The drone's resilience comes from a unique combination of stiff and elastic layers. An elastomer membrane is stretched and then sandwiched between rigid plates. When the system is at rest, the plates hold together and give the structure its stiffness. But when enough force is applied, the plates draw apart and the structure can bend. Researchers were able to define the moment at which the structure switches from stiff to flexible. Because the drone builds up elastic potential energy when it is folded up, it can unfold automatically when so instructed.

Structures that are stiff and flexible at the same time have a range of other potential applications as well. When developing the drone, the researchers used the same technology to create a soft-touch gripper that softens once it reaches a certain level of pressure so as not to break the object that it is picking up. This also means it cannot pick up a load that exceeds its capacity.

For more information, contact Laurence Baumann at laurence. This email address is being protected from spambots. You need JavaScript enabled to view it.; +41 21 693 16 34.