Researchers Use BCI to Control Robotic Arm

Research subjects fitted with a specialized, noninvasive brain cap were able to move a robotic arm just by imagining moving their own arms. Photograph courtesy of the College of Science and Engineering, UMN.

Researchers at the University of Minnesota (UMN) have demonstrated a brain-computer interface (BCI) that allows the user to control a robotic arm using only thoughts. Upon further development, the research has the potential to help people who have paralysis or neurodegenerative diseases, or it could be used to control a robotic prosthetic arm they said. The study was published online December 13 in Scientific Reports.

"Just by imagining moving their arms, they were able to move the robotic arm," said Bin He, PhD, a UMN biomedical engineering professor and lead researcher on the study.

The noninvasive technique, called EEG-based BCI, records weak electrical activity of the subjects' brain through a specialized, high-tech EEG cap fitted with 64 electrodes and converts the thoughts into action by advanced signal processing and machine learning. Eight healthy human subjects completed the experimental sessions of the study while wearing the EEG cap. Subjects gradually learned to imagine moving their own arms without actually moving them to control a robotic arm in 3D space. They started by learning to control a virtual cursor on a computer screen and then learned to control a robotic arm to reach and grasp objects in fixed locations on a table. Eventually, they could move the robotic arm to reach and grasp objects in random locations on a table and move objects from the table to a three-layer shelf by only thinking about these movements. All eight subjects could control a robotic arm to pick up objects in fixed locations with an average success rate above 80 percent and move objects from the table onto the shelf with an average success rate above 70 percent.

"This is exciting as all subjects accomplished the tasks using a completely noninvasive technique. We see a big potential for this research to help people who are paralyzed or have neurodegenerative diseases to become more independent without a need for surgical implants," He said.

The researchers said the BCI technology works due to the geography of the motor cortex-the area of the cerebrum that governs movement. When humans move, or think about a movement, neurons in the motor cortex produce tiny electric currents. Thinking about a different movement activates a new assortment of neurons, a phenomenon confirmed by cross-validation using functional MRI in a previous study He conducted. Identifying these assortments using advanced signal processing laid the groundwork for the BCI used by the UMN researchers, He said.

The robotic arm research builds upon He's research published three years ago in which subjects were able to fly a small quadcopter using the noninvasive EEG technology.

"Three years ago, we weren't sure moving a more complex robotic arm to grasp and move objects using this brain-computer interface technology could even be achieved," He said. "We're happily surprised that it worked with a high success rate and in a group of people."

Editor's note: This story was adapted from materials provided by UMN.