These Scientists Successfully Tested a Robotic Third Arm

We’ve all been there: Maybe you’re hauling your groceries to the front door that you need to unlock, or you’re carrying an order of coffee for a car full of friends, or you’re trying to juggle cooking dinner with taking care of your kids. You can’t help but think, “Man, I wish I had a third arm.”

Thanks to a team of scientists, that may soon become a reality. Neuroengineers at Ecole Polytechnique Federale de Lausanne (EPFL) have successfully developed and tested a design for a robotic third arm that’s controlled by your diaphragm. In a study published Wednesday in the journal Science Robotics, the team described how the device can help scientists gain a better understanding of the human brain—while also augmenting your body with an extra robotic arm (XRA).

“Users can adapt and learn to control XRAs,” Gieulia Dominijanni, a neuroengineer at EPFL and first author of the study, told The Daily Beast. “The thoughtful design of human-machine interfaces is key to ensure that the enhanced capabilities provided are not a mere remapping of existing abilities.”

The study builds off of previous research conducted by co-author and fellow EPFL neuroengineer Silvestro Micera into developing robotic prosthesis for amputees that can “feel” the things they touch. The difference with XRA, though, is that this device is purely for augmenting healthy human bodies. Doing so gives researchers unique insights into how the nervous system and brain work together to control limbs—even if they are entirely new.

For the experiment, the team had volunteers control a third arm in virtual reality. In the VR world, the user could control digital right and left arms using a real exoskeleton controlled by their hands. However, the third arm—which appeared as a symmetrical hand protruding from the torso area—was controlled by a belt wrapped around their diaphragm.

The belt measures their diaphragm’s movements, which correspond to the third arm’s movements. The researchers found that the control method didn’t interfere with how users breathed or talked—which was a major hurdle for the team. “One of the biggest challenges in the development of XRA lies in the implementation of control strategies that do not hinder natural abilities or the functionalities of biological limbs,” Dominijanni explained.

The team also tested an actual robotic arm using the diaphragm belt—albeit a much more simplified version that consisted of a rod that just extended in and out. Users were able to successfully control the XRA, hovering the rod over specified targets on a table.

Of course, that’s a far cry from being able to use a third robotic arm to unlock your door while your arms are full of groceries. However, the researchers say that future versions of XRA will have tons of potential uses—including life-saving measures.

“XRAs can have applications in high risk scenarios —such as search and rescue—where the ability to control a wearable extra robotic arm can be more effective and safe than having to coordinate multiple rescuers,” Dominijanni said. “The in depth study of such technologies and how users’ body and brain can adapt to them can also open new avenues in the assistive domain.”

Until then, the team plans to build off of their research to see how a potential third robotic arm might work in different environments such as the outdoors as well as real-world use cases. For now, we’re just going to have to continue working with the limbs that we got—or, at least, ask someone to lend a hand.