August 21, 2015

Multinational Team Develops BCI for Controlling an Exoskeleton

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Scientists at Korea University, Seoul, and Technical University of Berlin (TU Berlin), Germany, have developed a brain-computer interface (BCI) to control a lower-limb exoskeleton. Using an EEG cap, the system allows users to move forward, turn left and right, sit, and stand by staring at one of five flickering light-emitting diodes (LEDs). The results were published August 18 in the Journal of Neural Engineering.

A volunteer calibrates the BCI. Photograph courtesy of Korea University and TU Berlin.

Each of the five LEDs flickers at a different frequency, and when the user focuses attention on a specific LED, that frequency is reflected within the EEG readout. This signal is identified and used to control the exoskeleton. A key problem has been separating these precise brain signals from those associated with other brain activity and the artificial signals generated by the exoskeleton.

“Exoskeletons create lots of electrical noise,” said TU Berlin professor Klaus Muller, PhD, an author on the paper. “The EEG signal gets buried under all this noise—but our system is able to separate not only the EEG signal, but the frequency of the flickering LED within this signal.” Although the paper reports tests on healthy individuals, the system has the potential to aid people who are sick or who have disabilities.

“People with amyotrophic lateral sclerosis (ALS) or high spinal cord injuries face difficulties communicating or using their limbs,” Muller said. “Decoding what they intend from their brain signals could offer [the] means to communicate and walk again.”

The control system could serve as a technically simple and feasible add-on to other devices, with EEG caps and hardware now emerging on the consumer market. It took volunteers just a few minutes to be trained on how to operate the system. The researchers are now working to reduce the visual fatigue associated with longer-term users of such systems.

“We were driven to assist disabled people, and our study shows that this brain-control interface can easily and intuitively control an exoskeleton system—despite the highly challenging artifacts from the exoskeleton itself,” Muller said.

Editor’s note: This story was adapted from materials provided by Korea University and TU Berlin.

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