A robot dog in South Korea has made history by becoming the first four-legged robot to complete a full-length marathon without needing to recharge its batteries.

Named RAIBO2, the advanced quadrupedal robot, developed by researchers at the Korea Advanced Institute of Science and Technology (KAIST), covered the 42-kilometer distance of the Sangju Dried Persimmon Marathon in a time of 4 hours, 19 minutes, and 52 seconds.

This accomplishment is particularly notable as the marathon route includes two steep 50-meter elevation climbs, making it challenging even for human participants.

What is RAIBO2?

According to KAIST's official website, RAIBO2 is an evolved version of an earlier model called RAIBO, a quadrupled robot capable of running smoothly on diverse terrains like sandy beaches. Built by Professor Je Min Hwangbo's team from KAIST's Department of Mechanical Engineering, the robot incorporates cutting-edge design and engineering.

The researchers developed every aspect of RAIBO2 in-house, including its mechanical structure, electrical systems, and artificial intelligence software, says KAIST. This allowed the team to optimise the robot's walking efficiency, stability, and energy use, ensuring it could withstand the prolonged demands of a marathon course.

How does this robot dog work?

A key innovation in RAIBO2 is its ability to harvest energy. The robot is equipped with a special high-torque joint mechanism that allows it to regain energy while descending slopes, compensating for the power lost during uphill climbs. This feature was crucial for completing the challenging marathon course on a single battery charge, says KAIST.

The robot's walking capabilities are powered by reinforcement learning algorithms developed within KAIST's proprietary simulation environment, RaiSim, as explained in an article on KAIST's website. This simulator enabled researchers to train RAIBO2 to navigate complex terrains, including slopes, stairs, and icy roads, ensuring its performance would remain stable in real-world conditions.

According to KAIST PhD student Choongin Lee, a co-first author of the research, the marathon demonstrated RAIBO2's potential to perform practical tasks like delivery and security patrols in urban environments.

Looking ahead, the research team plans to integrate autonomous navigation functions, aiming to enhance the robot's capabilities for use in mountainous regions and disaster zones.

According to KAIST, this milestone was achieved with support from the Samsung Electronics Future Technology Promotion Center and the South Korea-based pedestrian robot startup Raion Robotics, with the achievement highlighting the growing role of quadrupedal robots in addressing real-world challenges, from patrolling hazardous areas to aiding in disaster response efforts.