This quadrocopter is controlled solely by the brain waves of a subject through the obstacle course. (Image: Bin He et al. / University of Minnesota)
Reading A remote-controlled helicopter flies agile through the room, steers through a series of tires without touching them. That's not very spectacular, you might think. But the whole thing has a peculiarity: The helicopter is not controlled by a conventional remote control, but only by thought. The brain currents of the controlling person derived via an electrode cap make it possible for the aircraft to fly to the left, right, up or down. This technique was developed by US researchers. They are looking for ways to help paralyzed people and people with disabilities check prostheses or assistive robots in the future. Almost exactly a year ago, a paraplegic US-American caused a stir worldwide. Because the 58-year-old had learned to control a robotic arm with her thoughts. He helped her to drink coffee again for the first time in almost 15 years. A small electrode implanted in her brain transmitted the necessary nerve signals to the control program of the robot arm. The disadvantage of this method: The electrode is implanted directly into the brain area responsible for movement - the patient must be operated on for this purpose and from now on constantly carry a cable connection in the skull. Two years ago, researchers from the University of Minnesota, Minneapolis, had already succeeded in solving this problem: "We have shown that a person can control a virtual helicopter on a screen by his own thoughts, " report study leader Bin He and his colleagues. The derivation of the brain signals was non-invasive on a like a swimming cap on the head sitting hood with electrodes.

Real helicopter instead of cursor or virtual image

In their current experiment, the researchers went one step further: their five subjects no longer navigated a picture on a computer screen, but a real, free-moving miniature helicopter. For this to work, the participants and with them also the control program of the human-machine interface first completed some training runs. At first, the subjects only practiced in front of a screen with a flashing cursor. They now imagined moving the cursor either to the right with their right hand or to the left with their left hand. The electrode cap attached to her head sent her brainwaves to the computer and it filtered out the signals that were responsible for the hand movements.

After a few tries, participants were able to move the cursor and even steer around obstacles. In another training, man and machine then learned to steer the cursor up and down by the mental bale or relaxing one hand. display

After these preliminary exercises, it became serious: After a short familiarization with a virtual helicopter, it went into the gym, where a real remote-controlled quadrocopter - a helicopter with four rotors - waited for the five participants. These sat with their backs to the room in front of a screen that transmitted the images of a small on-board camera of the helicopter. As if they were sitting in the cockpit, the subjects now saw from the perspective of a pilot, where the aircraft was flying. By practicing various hand movements as practiced, the participants could now let the helicopter fly up and down and left and right. How exactly they succeeded, the researchers tested by hanging a series of rings in the room, which should be controlled by the helicopter.

A quarter as good as the keyboard

"The subjects successfully managed to accurately control the helicopter in three dimensions, " the researchers report. In at least two-thirds of the tests, the participants flew all targets correctly and did not hit the wall or one of the rings. Within the maximum flight time of four minutes, they managed to fly through an average of three rings. For comparison: A control group, which controlled the helicopter by keyboard, created twelve rings. "Our human-machine interface thus achieved about a quarter of the keyboard standard that is the gold standard, " say the researchers. That's pretty good considering the short practice time and the difficulty of the task.

"Our experiment shows for the first time that humans can control the flight of a robot through thoughts - and this only with the help of externally derived brainwaves, " explains He. The next goal is now to develop this interface so that patients with paralysis or neurodegenerative diseases can use them - for example, to control robotic arms or other technical aids via the electrode cap.

Bin He (University of Minnesota, Minneapolis) et al., Journal of Neural Engineering - === Nadja Podbregar

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