In a potential breakthrough in wearable sensing technology, researchers from Cornell and the University of Wisconsin, Madison, have designed a wrist- mounted device that continuously tracks the entire human hand in 3D.
The bracelet, called FingerTrak, can sense and translate into 3D the many positions of the human hand, including 20 finger joint positions, using three or four miniature, low-resolution thermal cameras that read contours on the wrist. The device could be used in sign language translation, virtual reality, mobile health, human-robot interaction, and other areas, the researchers said.
Past wrist-mounted cameras have been considered too bulky and obtrusive for everyday use, and most could reconstruct only a few discrete hand gestures.
FingerTrak’s breakthrough is a lightweight bracelet, allowing for free movement. Instead of using cameras to directly capture the position of the fingers, the focus of most prior research, FingerTrak uses a combination of thermal imaging and machine learning to virtually reconstruct the hand. The bracelet’s four miniature, thermal cameras — each about the size of a pea — snap multiple “silhouette” images to form an outline of the hand.
A deep neural network then stitches these silhouette images together and reconstructs the virtual hand in 3D. Through this method, the researchers were able to capture the entire hand pose, even when the hand was holding an object.
“The most novel technical finding in this work is discovering that the contours of the wrist are enough to accurately predict the entire hand posture,” said Cheng Zhang, assistant professor of information science and director of Cornell’s new SciFi Lab. “This finding allows the reposition of the sensing system to the wrist, which is more practical for usability.”
The technology has a wide range of possible uses, but Zhang said the most promising is its potential application in sign language translation.
“Current sign language translation technology requires the user to either wear a glove or have a camera in the environment, both of which are cumbersome,” he said. “This could really push the current technology into new areas.” According to the researchers, FingerTrak could also have an impact on health care applications, specifically in monitoring disorders that affect fine-motor skills. How we move our hands and fingers often tells about our health condition, so a device like this might be used to better understand how the elderly use their hands in daily life, helping to detect early signs of diseases like Parkinson’s and Alzheimer’s.