Motion capture requires special equipment and infrastructure that can cost upward of $100,000 — but scientists have created a smartphone app and combined this with an AI algorithm to do the same job.

Movin cofounder and CEO Byeoli Choi standing next to a Tracin device. Movin, a startup that develops AI-based real-time motion capture devices, has raised 4 billion won (about $2.7 million) in a ...