For the first time, researchers can track the movement of a person’s entire body with ultrasonic sound waves, using just an off-the-shelf smartwatch and a lightweight artificial intelligence model—all while ensuring privacy and efficiency.

The new technology, called EchoMotion, was developed by Cornell’s Smart Computer Interfaces for Future Interactions (SciFi) Lab, directed by Cheng Zhang, associate professor of information science in the Cornell Ann S. Bowers College of Computing and Information Science. It uses the built-in speaker and microphone on a commercial smartwatch to determine a person’s body position using a sonar-like sensing system. Once EchoMotion is integrated into commercial wearables or virtual reality (VR) systems, it could be used for tracking workouts, daily activities and progress on physical rehabilitation.

EchoMotion represents a scalable approach that can use AI to understand human behaviors in the real world, Zhang said.