The robots can run now. Stopping is the problem.

At the second World Humanoid Robot Games in Beijing in August, the winning time in the 100-meter dash was about 9.3 seconds. At the first games a year earlier, it was 21.5.

The field grew too, from roughly 500 machines to more than 2,000, and the track events were switched this year from remote control to fully autonomous. According to the Associated Press, human handlers were still all over the venue, lifting robots, separating them, swapping batteries and adjusting limbs.

What has not improved is the finish. Sprinters crossed the line at full speed, did not slow down, and struck the padded blue wall at the end of the track. One folded at the waist. One threw sparks and caught fire. Crews carried robots off on stretchers.