Carnegie Mellon University researchers have found ways to track body movements and detect shape changes using arrays of RFID tags. RFID-embedded clothing thus could be used to control avatars in video games — much like in the movie "Ready Player One." Or embedded clothing could to tell you when you should sit up straight — much like your mother.
RFID tags are nothing new, which is part of their appeal for these applications, said Haojian Jin, a Ph.D. student in CMU's Human-Computer Interaction Institute (HCII). They are cheap, battery-free and washable.
What's new is the method that Jin and his colleagues devised for tracking the tags, and thus monitoring movements and shapes. RFID tags reflect certain radio frequencies. It would be possible — but not practical — to use multiple antennas to track this backscatter and triangulate the locations of the tags. Rather, the CMU researchers showed they could use a single, mobile antenna to monitor an array of tags without any prior calibration.
Just how this works varies based on whether the tags are being used to track the body's skeletal positions or to track changes in shape. For body movement tracking, arrays of RFID tags are positioned on either side of the knee, elbow or other joints. By keeping track of the ever-so-slight differences in when the backscattered radio signals from each tag reach the antenna, it's possible to calculate the angle of bend in a joint.
"By attaching these paper-like RFID tags to clothing, we were able to demonstrate millimeter accuracy in skeletal tracking," Jin said.
The researchers call this embedded clothing RF-Wear and described it earlier this year at the UbiComp 2018 conference in Singapore. It could be an alternative to systems such as Kinect, which use a camera to track body movements and can only work when the person is in the camera's line of sight. It also could be an alternative to existing wearables, which generally depend on inertial sensors that are expensive, difficult to maintain and power hungry, Jin said.
RFID-embedded clothes might be an alternative to wrist-worn devices, such as Fitbit, for activity tracking or sports training.