South Korean 'robot dog' became first to run a marathon on a single battery charge — now we know how

A four-legged robot named RAIBO2 became the first quadruped robot to complete an official marathon without recharging its battery in 2024. The robot covered a 26.2-mile (42.2-kilometer) route on a hilly public-road course during the Sangju Dried-Persimmon Marathon in South Korea. The achievement was detailed in a study published in the journal Nature on September 23, 2024.

RAIBO2's ability to run the marathon demonstrated significant progress in overcoming a major limitation for quadruped robots: their endurance. The developers explained that powering multiple joints while stabilizing the robot's body consumes a large amount of energy. To achieve the record, the team boosted the robot's battery capacity by 33%, optimized its control system, and used lightweight mechanical components with efficient energy transmission.

The robot's total cost of transport, which measures energy required to move a body over a distance, was 0.25, compared to a human benchmark of 0.37. This efficiency made RAIBO2 the first quadruped robot to surpass that figure. The team estimated that RAIBO2 could travel up to 15.5 miles (25 km) farther with its current battery capacity, extending its maximum range to 41.6 miles (67 km).

With such endurance, quadruped robots like RAIBO2 could be useful in disaster zones and mountainous areas, carrying cameras, sensors, or communications gear across challenging terrain where wheeled robots would struggle.