The competition, however, showed how difficult it remains for robots to perform reliably outside controlled laboratory conditions.

　　Rain affected the competition, while changes in lighting and the outdoor environments added uncertainty to the robots" visual recognition and manipulation tasks. A team from UniX AI, a company well-known for its robot applications on real-world scenarios and has just raised a new round of 300 million yuan ($ 44.49 million) in late March, completed its run within the allotted time, but its robot moved relatively slowly compared to human firefighters" real practice. When operating the fire extinguisher, its robotic hand had to make two attempts to align with the target.

　　Of 12 teams competed on Sunday, three finished the challenge.

　　Yang Liqi, a representative of the UniX AI team, told the Global Times that the firefighting scenario placed higher demands on both the robot"s recognition and manipulation capabilities.

　　"Rain and lighting conditions can affect the robot, and actual situations are often different from what we simulate in the laboratory," Yang said, noting that this was also one reason why a number of teams were unable to complete their runs on Sunday morning.

　　The team had programmed the robot to make up to three attempts when operating the extinguisher. "If it sees white smoke after the first attempt, it will not make a second attempt," Yang said.

　　The difficulty was not simply that whether the robot could move its arm. Humanoid robots rely on different types of joints for different tasks: small, high-precision joints enable delicate hand operations, while high-torque, reliable joints support movement and balance.