New Delhi, April 19 -- In a spectacle blending athleticism with advanced engineering, 21 humanoid robots lined up alongside thousands of runners at the Yizhuang half-marathon in Beijing on Saturday (April 19). For the first time, these machines raced the full 21-kilometre (13-mile) course alongside human participants.

The robots-designed by companies such as DroidUP and Noetix Robotics-came in all shapes and sizes. Some were less than 120 cm (3.9 ft) tall, while others towered at 1.8 meters (5.9 ft). Their appearance varied just as widely.

Despite the marathon setting, Beijing officials compared the event more to a race car competition, given the engineering precision, battery management, and need for navigation support.

Each robot was...