Army-Funded Discovery Paves Way For Self-Propelled Robots

Robots relying solely on their own energy to move around have just moved one step closer to being a reality thanks to an experiment by University of Massachusetts Amherst researchers.

While watching a gel strip dry during an experiment, the researchers discovered how to make cutting-edge materials that snap and reset themselves, only relying upon energy flow from their environment. Researchers say that this discovery has the potential to make future military robots that are able to move off their own energy possible. 

The research, funded by the U.S. Army, was published in Nature Materials.

'A mundane experiment' leads to a discovery

The physics of the discovery unveiled itself during a "mundane experiment" where the researchers were watching a gel strip dry. What they saw guided them to a revelation: when the long, elastic gel strip's internal liquid evaporated, the strip moved.

Most of its movements were rather slow, but at certain points, they occasionally sped up, causing snap instabilities. Such faster movements continued to occur as the strip lost more of its internal liquid.

In further studies, the researchers saw that the strip's material and shape mattered. Moreover, the strips could reset themselves to continue their movements.

Utilizing snap instabilities 

This sort of snap instabilities is present in the animal and plant worlds, with especially small animals using special parts that help them move really fast. While this was already used to create fast movements in small robots, most of them required a motor or human intervention to keep them moving.

In order to tackle this issue, the researchers experimented with different shapes to find which ones could move repeatedly without any motors or human intervention.

The team was able to show that their reshaped strips could move, demonstrating how they can climb stairs on their own.

"These lessons demonstrate how materials can generate powerful movement by harnessing interactions with their environment, such as through evaporation, and they are important for designing new robots, especially at small sizes where it's difficult to have motors, batteries, or other energy sources," said Dr. Al Crosby, a professor of polymer science and engineering in the College of Natural Sciences, UMass Amherst.