Four-legged robot completes a full marathon on a single battery

The four-legged robot "Raibo2" has completed a full marathon without a battery swap. Developed by a KAIST research team, the robot was registered as an actual participant in the 2024 Sangju persimmon marathon, crossing the finish line in 4 hours, 19 minutes and 52 seconds — the first time a quadruped robot has ever completed the full 42.195 km marathon course.

The key to the feat was not a large-capacity battery, but improved efficiency. The research team analyzed the energy losses occurring in the legs, motors, electrical systems and gait control, and took an integrated design approach that treated the mechanical structure, electrical system and gait control as a single system problem.

During the marathon run, voltage, current, temperature and battery status were measured and recorded in real time, and synchronized with position, speed and altitude data from GPS. Researchers ran alongside the robot, filming the entire course, proving the feasibility of long-distance running with data.

The findings were published in the main journal of the international academic journal Nature on September 23 (local time), marking the first time robotics research conducted in South Korea has appeared in the print edition of Nature. Dr. Lee Chung-in of KAIST's Department of Mechanical Engineering, along with students Yeom Dong-hoon and Park Jeong-su, participated in the study as co-first authors.

Professor Hwangbo Je-min's research team in KAIST's Department of Mechanical Engineering aims to further develop Raibo2's technology into products capable of extended use in industrial settings, with a next goal of creating robots that go beyond a single strong performance to move for long hours on site every day.