Bin He, a University of Minnesota biomedical engineering professor and lead researcher on the study, said: “This is the first time in the world that people can operate a robotic arm to reach and grasp objects in a complex 3D environment using only their thoughts without a brain implant.”
The noninvasive technique, called electroencephalography (EEG) based brain-computer interface, records weak electrical activity of the subjects' brain through an EEG cap fitted with 64 electrodes and converts the ‘thoughts’ into action by advanced signal processing and machine learning.
Eight subjects gradually learned to imagine moving their own arms without actually moving them to control a robotic arm in 3D space. They started from learning to control a virtual cursor on computer screen and then learned to control a robotic arm to reach and grasp objects in fixed locations on a table. Eventually, they were able to 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% and move objects from the table onto the shelf with an average success rate above 70%.
Prof He said: “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 paralysed or have neurodegenerative diseases to become more independent without a need for surgical implants.”
The researchers said the brain-computer interface 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 prof He's previous study. Sorting out these assortments using advanced signal processing laid the groundwork for the brain-computer interface used by the University of Minnesota researchers.
The robotic arm research builds upon prof He's research published three years ago in which subjects were able to fly a small quadcopter using the noninvasive EEG technology.
Prof He anticipates the next step of his research will be to further develop this brain-computer interface technology by developing a brain-controlled robotic prosthetic limb attached to a person's body or examining how this technology could work with someone who has had a stroke or is paralysed.