Enhancing the Body with Wearable, Robotic Arm Using Cognitive Techniques

Silvestro Micera is a neuroengineer who works on cutting-edge technologies that can help people regain sensory and motor skills they have lost because of brain injuries or other conditions. His work on improving the human body and mind with technology had never been done before. Micera and his team have now released a study in the journal Science Robotics that shows how to use diaphragm movement to successfully control an extra arm. This would be like adding a third robotic arm to a healthy person."

This study opens up new and exciting opportunities, showing that extra arms can be extensively controlled and that simultaneous control with both natural arms is possible," says Micera, Bertarelli Foundation Chair in Translational Neuroengineering at EPFL, and professor of Bioelectronics at Scuola Superiore Sant'Anna.

The study is part of the Third-Arm project, which was previously funded by the Swiss National Science Foundation (NCCR Robotics). The goal of the project is to make a wearable robotic arm that can help with daily tasks or search and rescue.

Micera believes that looking into the cognitive limits of third-arm movement could lead to a better understanding of how the brain works. 
To look into the cognitive limits of enhancement, the researchers first created a virtual world where a healthy person could move their diaphragm to control a virtual arm. They found that controlling your diaphragm doesn't get in the way of things like directing your gaze, speech, or physiological arms. The person using this virtual reality set-up has a belt that tracks the movement of their stomach.

When someone puts on a virtual reality mask, they see three arms: the right arm and hand, the left arm and hand, and a third arm in the middle with a six-fingered hand that is the same on both sides.

Micera continues, "The main motivation of this third arm control is to understand the nervous system. If you challenge the brain to do something that is completely new, you can learn if the brain has the capacity to do it and if it's possible to facilitate this learning. We can then transfer this knowledge to develop, for example, assistive devices for people with disabilities, or rehabilitation protocols after stroke."

"We want to understand if our brains are hardwired to control what nature has given us, and we've shown that the human brain can adapt to coordinate new limbs in tandem with our biological ones," explains Solaiman Shokur, co-PI of the study and EPFL Senior Scientist at the Neuro-X Institute. "It's about acquiring new motor functions, enhancement beyond the existing functions of a given user, be it a healthy individual or a disabled one. From a nervous system perspective, it's a continuum between rehabilitation and augmentation."

Gillian Dominijanni, a PhD student at EPFL's Neuro-X Institute, says, "We made this hand symmetric to avoid any bias towards either the left or the right hand."  Then, in the virtual world, the person is asked to reach out with their left hand, their right hand, or the middle hand, which is symmetrical. The person in the real world holds on to an exoskeleton with both arms, which lets them move the left and right computer arms. The virtual middle, symmetric arm is controlled by the movement picked up by the belt around the abdomen. Over 150 meetings, 61 healthy people were used to test the setup. 

""Diaphragm control of the third arm is actually very intuitive, with participants learning to control the extra limb very quickly," explains Dominijanni. "Moreover, our control strategy is inherently independent of the biological limbs and we show that diaphragm control does not impact a user's ability to speak coherently."

The researchers were also able to test diaphragm control with a real robotic arm. It was a simple arm made up of a rod that could be stretched out and then brought back in. The rod is stretched out when the person contracts the diaphragm. The person in an experiment that is like the VR world is asked to use her left or right hand, the robotic stick, or both to reach and hover over target circles. 

Along with the diaphragm, but not included in the study, the vestigial ear muscles have also been tried to see if they can be used to do new things. This method involves giving a person monitors in their ears and teaching them how to use small movements in their ears to move a computer mouse. "Users could potentially use these ear muscles to control an extra limb," says Shokur, stressing that these different ways of controlling things could one day help researchers come up with better ways to help people who have trouble moving their bodies. As part of the third arm project, earlier research on controlling robotic arms has focused on making life better for people who have lost limbs. The newest study in Science Robotics goes one step further than fixing the human body and moves toward making it bigger.

"Our next step is to explore the use of more complex robotic devices using our various control strategies, to perform real-life tasks, both inside and outside of the laboratory. Only then will we be able to grasp the real potential of this approach," concludes Micera.

Source:

Ecole Polytechnique Fédérale de Lausanne. "Cognitive strategies for augmenting the body with a wearable, robotic arm." ScienceDaily. ScienceDaily, 13 December 2023. <www.sciencedaily.com/releases/2023/12/231213143711.htm>.

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