Commas = pauses?

The robot, which is capable of detailed, subtle movements, was made by piling layers of thin film material.
After creating a foldable blueprint of the desired object, the researchers print the blueprint and connect the layers with a string to create a 3D figure.

When I heard the sentences, there were no pauses, so I understood it as 'The robot which is capable of detailed, subtle movements was' and I thought it was a defining relative clause.

However, when I saw the sentences, there were commas and it means it is a non-defining relative clasue.

And then I am confused again.

Must there be commas in the sentences or sentences without commas are possible? And then what differences are there between them?

How can I figure out whether there are commas or not when there are no pauses in spoken English?

Thank you so much as usual and have a good day.

http://www.arirang.com/News/News_View.asp?nseq=221122

This robot delivers lines from a movie and captures the emotions of the character.

(CG )
"You know, my father was right. … Richard Parker never saw me as his friend" - Life of Pi (2012)

This time, it reacts emotionally to music.
The robot, which is capable of detailed, subtle movements, was made by piling layers of thin film material.
After creating a foldable blueprint of the desired object, the researchers print the blueprint and connect the layers with a string to create a 3D figure.

"Using the same techniques as 3D printing, it creates the desired 3D figure by repeating layers from the bottom. It takes about two to three hours."

When the researchers press the strings, the robot moves like a marionette puppet.
When combined with artificial intelligence technology, the robot can perform more functions.

"If combined with an intelligence structure, it will be able to react to what I say and interact as such."

The researchers expect the robot to be used for graphics production in the film industry.