KAIST team demonstrates quadruped robot completing a marathon on one charge

2 min read•Sep 23, 2026•

A KAIST team demonstrated RAIBO2 completing the Sangju Marathon on one battery charge, first reported by Techxplore. The demonstration matters because recent quadruped robots have been limited to approximately 20 kilometers, while longer operational ranges could improve the usefulness of legged machines that may assist rescue operations in mountainous or disaster-stricken areas.

The four-legged robot completed the course in 4 hours and 19 minutes alongside human runners, maintaining an average speed of 2.64 meters per second (5.9 miles per hour). The route included 286 meters (938 feet) of elevation change and slippery sections of terrain.

Legged robots must continuously spend energy supporting their body weight and compensating for energy lost with each step. That burden helps explain why recent quadruped robots have been limited to approximately 20 kilometers, unlike robots on wheels.

RAIBO2 addresses that range problem through hardware and software: lightweight legs, optimized motor-driving circuits and movement rules reinforced by machine learning. The design is intended to reduce energy loss and extend the distance the robot can travel between charges.

After the marathon, RAIBO2 had used 1,280 watt-hours and achieved an average total cost of transport of 0.25, a measure of energy expended during motion that factors in the robot’s weight. The paper’s authors propose that RAIBO2 is the first quadruped robot with a lower cost of transport than the human value of 0.37.

That gives the demonstration two distinct efficiency markers: marathon distance on one charge and a transport cost below the human reference. RAIBO2’s total battery capacity was 2,016 Wh, and the authors estimate that it could have traveled a further 25 kilometers (16 miles).

The robot travels approximately three times as far per battery charge as existing quadruped robots. The findings aim to extend the operational ranges and utility of legged robots, which have potential to assist in rescue operations in mountainous or disaster-stricken areas.

Oct 7, 2026

Arizona appeals court vacates manslaughter sentence after AI video

An Arizona appeals court vacated the 10.5-year sentence of Gabriel Horcasitas while upholding his manslaughter conviction, first reported by Nytimes. The case returns to Maricopa County Superior Court for resentencing without the video, after judges found that it presented scripted statements as if the victim himself were speaking in court.

The three-judge panel said the video generated a likeness of Christopher Pelkey’s voice and appearance but did not reflect actual events. It found that allowing and relying on the video made the sentencing fundamentally unfair, and noted that no prior Arizona case had addressed the admissibility of such a depiction at sentencing.

The judges said a victim’s right to speak cannot override a defendant’s right to be sentenced on accurate, reliable information. They said the video collapsed the distinction between the family’s belief about what Pelkey would have said and Pelkey’s own voice and opinions.

The ruling distinguishes family members speaking about Pelkey from a generated likeness that appeared to speak for him.

Pelkey’s sister, Stacey Wales, presented the video during Horcasitas’s sentencing alongside victim-impact statements from family and friends. Wales wrote the script and said her husband and the couple’s longtime business partner helped create the video using Pelkey’s voice from a YouTube video and his face and torso from a funeral-service poster.

Judge Todd F. Lang praised the video as genuine, then imposed the maximum sentence of 10.5 years, more than the nine years prosecutors had sought.

Wales said nobody intended to make the court believe Pelkey was alive or that he had recorded the video before his death. She said she disagreed with the ruling and argued that families use slide shows, collages, hypothetical conversations and poetry to convey grief.

Wales compared the AI video with photography, saying it took 15 years of landmark cases around the 1860s before photography was widely accepted in courts.

The case returns to Maricopa County Superior Court for a new sentencing hearing without the AI-generated video.