Soft, energy-efficient robotic wings soon

Researchers have discovered a new resonance phenomenon in a dielectric elastomer rotary joint that can make the artificial joint bend up and down, like a flapping wing.

The new discovery by scientists from Harbin Institute of Technology, China and the University of California, Los Angeles (UCLA), has potential in soft robotic applications as lightweight, energy-efficient flapping wings.

Dielectric elastomers are novel materials with soft and lightweight properties, resembling human muscle, that can undergo large active deformations.

This has made dielectric elastomers popular for creating devices such as robotic hands, soft robots, tunable lenses and pneumatic valves.

The study appeared in the journal Applied Physics Letters.

"The dielectric elastomer is a kind of electro-active polymer that can deform if you apply a voltage on it," said Jianwen Zhao from Harbin Institute of Technology.

"We found that alternating voltages can make the joint continuously bend at different angles.

Especially, when the rotational inertia of the joint or the applied voltage is large enough, the joint can bend beyond 90 degrees to 180 degrees, following a principle different from the normal resonance rule," Zhao explained.

Zhao said this new phenomenon makes the dielectric elastomer joint a good candidate for creating a soft and lightweight flapping wing for robotic birds.

These wings would be more efficient than bird wings based on electrical motors due to the higher energy conversion efficiency (60 to 90 percent) of the dielectric elastomer.

This new phenomenon may open doors for many novel soft devices, such as soft and lightweight robots for circumstances with restricted space and weight requirements or flapping wings of soft robotic birds that can generate a large lift force, Zhao noted.