[jrumbut]

It's appalling the robot was designed to ever use that much force in the grip. Even if the chess pieces were made of lead I can't see it being needed. In general, more attention to failing safe.

But the kid is some kind of local chess champion, I can't fully fault the decision to have him play with the experimental chess robot. Is it more dangerous than a lawn mower or a blender or any other machine that 9 year olds might begin to operate?

[NamTaf]

Correct. The fact they made a robot that could crush a human hand means they paid no attention to this hazard. Competent execution of Safety in Design concepts would demand limiting the grip force to only what's necessary to reliably move the pieces, which almost certianly wouldn't break bone. If that isn't possible, then it would imply the requirement to find some other way to resolve this hazard in the heirarchy of controls.

Relying on a human is the last option, not the default, when it comes to safety. Human adaptability is not a licence to hand-wave away design responsibility. The most glaring example is Tesla, who is unforgivably guilty of this.

This is bog-standard competent engineering in almost all domains of engineering. It is the table stakes-level expectation of a reasonable approach to safety. I'd literally end up in jail if something went wrong and I had been found to not consider these factors.

Software- and computer-related domains of engineering are a conspicuous outlier when it comes to this philosophy.

[jrumbut]

You would think that much force would lead to broken actuators and chess pieces often enough during development that someone would land on the idea of setting an upper limit on all forces just to save money.