China's humanoid robots are stealing the show, but a quieter machine revolution is unfolding - BBC News

There are more than two million robots working in China's factories - and they are scaling up fast.

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Watch: BBC visits factories in China with robot workers

"I take a nap and the world changes," says Chen Tianyu.

His world certainly does. The 28-year-old keeps up with the latest technology by spending his spare time in factories that are switching to automation. That way he knows what to prioritise when teaching his class about artificial intelligence (AI) and robotics.

In front of him, around 30 college students are studying code. One of them is typing furiously as his eyes dart from the screen to the robot: "The idea is it will grab that cylindrical piece and move it over there."