Shape-shifting 'transformer bots' inspired by origami

"The question we're asking is how to achieve a number of versatile shapes with the fewest number of actuators powering the shapeshifting," said Jie Yin, associate professor of mechanical and aerospace engineering and co-corresponding author of a paper describing the work. "Here we use a hierarchical concept observed in nature -- like layered muscle fibers -- but with plastic cubes to create a transforming robot."

The NC State researchers assembled hollow, plastic cubes using a 3D printer and assembled 36 of them together with rotating hinges; some hinges were fixed with metal pins, while others were activated wirelessly with a motor.

The researchers were able to move the cubes into more than 1,000 shapes using only three active motors. Those shapes included tunnel-like structures, bridge-like structures and even multi-story architectures.

The untethered transformer bots can move forward, backward and sideways -- without feet -- merely by controlling the ways the structure's shape changes. The bots can also transform relatively quickly from flat, or fully open, to a boxlike larger cube, or fully closed. The bots also can carry a load about three times their own weight.

Next, the researchers will attempt to make the transformer bots even better.

"We want to make a more robust structure that can bear larger loads," said Yanbin Li an NC State postdoctoral researcher and co-corresponding author of the paper. "If we want a car shape, for example, how do we design the first structure that can transform into a car shape? We also want to test our structures with real-world applications like space robots."

"We think these can be used as deployable, configurable space robots and habitats," said Antonio Di Lallo, an NC State postdoctoral researcher and co-first author of the paper. "It's modular, so you can send it to space flat and assemble it as a shelter or as a habitat, and then disassemble it."

"For users, it needs to be easy to assemble and to control," Yin said.

Hao Su, associate professor of mechanical and aerospace engineering, is a co-corresponding author of the paper. Junxi Zhu, an NC State Ph.D. student, Yinding Chi, a former Ph.D. student at NC State, also co-authored the paper.

The findings appear in Nature Communications. Funding for the research was provided by the National Science Foundation under grants CMMI-2005374, CMMI-2126072 and 2231419.