November 19, 2019 – A team of researchers at the MIT Media Lab have devised an algorithm that they state will improve the simultaneous tracking of any number of magnets, which, according to the researchers, has significant implications for prostheses, augmented reality, robotics, and other fields.
Graduate student Cameron Taylor, lead researcher on the approach in the Media Lab’s Biomechatronics group, says the algorithm dramatically reduces the time it takes for sensors to determine the positions and orientations of magnets embedded in the body, wood, ceramics, and other materials.
Prostheses have relied on electromyography (EMG) to interpret messages from a user’s peripheral nervous system. Electrodes attached to the skin adjacent to muscles measure impulses delivered by the brain to activate them. However, this system is less-than-perfect, and wearing such devices can be uncomfortable.
Using magnets which can be embedded in the body indefinitely to control high-speed robotics is an alternative to EMG, but according to researchers, this method took computers too long to determine precisely where the magnets were and initiate a reaction. To decrease the time delay in magnet tracking, a computer would need to quickly identify the orientation of the magnets – something that graduate student Cameron Taylor realised could be achieved using simple computer coding techniques.
Another problem that Taylor and members of his research team had to solve was that of disturbance from the Earth’s magnetic field, which can complicate magnet tracking. Traditional methods of eliminating this interference weren’t practical for the type of compact, mobile system needed for prostheses and exoskeletons. The team solved this issue by programming their computer software to search for the Earth’s magnetic field as if it is simply another magnetic signal.
According to Taylor, and also Hugh Herr, Professor of Media Arts and Sciences at MIT and head of the Biomechatronics group, the new method means that magnetic target tracking can be extended to high-speed, real-time applications that require tracking of one or more targets, eliminating the need for a fixed magnetometer array. Software enabled with the new algorithm could greatly enhance reflexive control of prostheses and exoskeletons, simplify magnetic levitation, and improve interaction with augmented and virtual reality devices.
“All kinds of technology exists to implant into the nervous system or muscles for controlling mechatronics, but typically there is a wire across the skin boundary or electronics embedded inside the body to do transmission,” Herr says. “The beauty of this approach is that you’re injecting small passive magnetic beads into the body, and all the technology stays outside the body.”
The Biomechatronics group at MIT is primarily interested in using its new findings to improve control of prostheses. However, Hisham Bedri, a graduate of the Media Lab who works in augmented reality, commented that potential applications of the advances could be huge for the consumer market. “If you wanted to step into the virtual reality world and, say, kick a ball, this is super useful for something like that,” Bedri said. “This brings that future closer to a reality.”
The group has applied for a patent on its algorithm and its method for using magnets to track muscle movement. It is also working with the U.S. Food and Drug Administration (FDA) on guidance for the transition of high-speed, broad bandwidth magnetic tracking into the clinical realm.
The researchers are now preparing to conduct preclinical work to confirm that this technique will work for tracking human tissues and controlling prostheses and exoskeletons. “I think it’s possible we would begin human testing as soon as next year,” Herr added. “This isn’t something that’s 10 years out at all.”
The work, “Low-Latency Tracking of Multiple Permanent Magnets,” has been published by IEEE Sensors Journal.
Image & video credit: MIT Media Lab/YouTube