You must have had times when your two hands were not enough and you wished you had a third arm. Scientists have discovered that the robot's third arm can actually be controlled very easily through the movement of the diaphragm muscles. The research was conducted at the EPFL Institute in Switzerland by a team led by Professor Silvestro Micera. The research is part of a large "third arm" project of the Swiss National Center for Research Competence.
To conduct this study, we built a device in which users sit while grabbing handles on two exoskeleton-style arms and wear a belt equipped with sensors to detect their chart movements. They also wore a VR headset through which they viewed the virtual environment.
By moving the exoskeleton arm, users can perform tasks with a virtual version of their real arm in the VR world. Additionally, by moving the diaphragm in specific ways, users can control a virtual third arm. The third arm is located between the virtual left and right arms and is designed as a symmetrical six-fingered hand - with a thumb on each side - so that it is not perceived as belonging to one side or the other.
In 150 tests with 61 volunteers, it turned out that most people could easily master this setup. Importantly, the test subjects were able to control their left and right arms while simultaneously controlling a third arm - sort of like patting their head and rubbing their belly at the same time.
While operating the third arm, participants were also able to engage in conversation and look away from the task.
In subsequent phases of the study, volunteers had a physical robotic arm strapped to their chests. The device is really just a rod that extends in and out from the base, but the user can still move it so that its "hand" hovers over a given target circle as directed.
Nonetheless, this research is not specifically aimed at developing a practical third robotic arm.
"The main motivation for this third-arm control is to understand the nervous system," Misela said. "If you challenge the brain to do something completely new, you can learn whether the brain is capable of doing it and whether it is possible to facilitate this learning. We can then use this knowledge to develop assistive devices for people with disabilities or rehabilitation programs after stroke, for example."
A paper on the research was recently published in the journal Science Robotics. You can see the virtual and physical third arm in action in the video below.