RAIBO2 completed the 42.195 km Sangju Dried Persimmon Marathon in South Korea in November 2024. It finished in 4 hours, 19 minutes and 52 seconds. Its developers described the performance as the first full marathon completed by a quadruped robot at an official event.

A Nature paper published nearly two years later details work by a Korea Advanced Institute of Science and Technology team led by associate professor Jemin Hwangbo. The researchers combined lightweight hardware, low-loss motor-driving circuitry and a locomotion policy optimized with reinforcement learning. RAIBO2 travelled at an average 2.64 metres per second, handled 286 metres of elevation change and climbed slopes of up to 18.4 degrees. The team reports more than three times the range per charge achieved by recent comparable quadrupeds, which typically cover about 20 km.

The robot drew 1,280 watt-hours from a 2,016 Wh battery. Its total cost of transport was 0.25, compared with a human benchmark of 0.37, which the researchers identify as a first for a quadruped robot. Humans remain faster. Kenya's Sabastian Sawe set the official marathon record at 1 hour, 59 minutes and 30 seconds at the London Marathon in April, becoming the first competitor to break two hours.

Legs consume more energy than wheels on smooth ground, but they can cross stairs, rubble, slopes and other uneven surfaces. That makes quadrupeds candidates for mountainous areas and disaster zones. Robot dogs are already used in the nuclear clean-up at the UK's Sellafield facility, and military uses are also being considered.

RAIBO2's efficiency does not make it autonomous. Stairs and mountainous terrain may require different energy-loss models, constrained postures and stronger environmental awareness. The study used a human operator. Autonomous operation would need planners that understand a global map and choose energy-efficient routes. The researchers see their loss models as a basis for extending the range of future legged robots used for disaster inspection, deliveries or other missions.