Three parts, one loss budget
Choongin Lee and colleagues at KAIST in Daejeon, in a study in the journal Nature, built RAIBO2 as three parts that share one loss budget: a force-transparent lightweight mechanism, a low-resistance motor driver and a locomotion controller that dissipates less energy. The study says RAIBO2 finished a full marathon in 4 hours, 19 minutes and 52 seconds on a single battery charge.[1]
0.25 set against a human 0.37
The total cost of transport is 0.25. The human benchmark is 0.37. Range per charge is more than 3 times that of existing quadrupeds. The loss figure uses a 1447 Wh pack.[1]
The 0.25 result is the output of that three-part loss budget. An alternative reading ties the 0.37 human benchmark to the literature. The 2024 course has no paired human time in the comparison.[1]
The 2024 timing still stands
The cited race timing is from 2024. The study in the journal Nature is the loss budget that splits that time into parts. The measurement to watch is another laboratory reporting the same 0.25 on another course and another battery.[1]