Comment by michaelt | Hacker News Reader

Comment by michaelt | Hacker News Reader

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I've worked on much less expensive, much smaller humanoid robots.

These robots are certainly running through a scripted set of poses which has been extensively tested for the conditions (Humans would also be choreographed and have to hit certain marks at certain times). If you covered the stage in loose gravel or a thick carpet they'd all start falling over. The things the robots hold are almost certainly taped into their hands.

Despite that, this is a very impressive demo. Those robots are $40k+, they've got 20+ of them. And not a single one fell over. They're fast too - and there are a load of corners they could have cut, but they didn't.

The floor has two textures, it would have been easier without that. The humans right alongside them? Much less safety paperwork without them. The robot wearing trousers and a cape? Much easier without that. The fewer robots you have, the lower the chances on falls over landing their backflip. Lose the audience and record it in multiple takes. Hell, you could have human acrobats in robot costumes and it'd cost far less and be much easier.

So this demo is very much a costly signal of confidence.

> The things the robots hold are almost certainly taped into their hands.

You can clearly see that the robots change their grip of their sword, so it cannot be taped to their hands.

When is that?

With the poles at the 1 minute mark, the robots enter holding them and their left hand never moves on the pole. Also note the stationary hand is matte grey while the moving hand is metallic silver.

Likewise with the wine gourds (?) at 2m30s and the nunchucks at 3m40s.

It’s a completely sensible design decision, much simpler to do cartwheels and vaults if you don’t have super delicate fingers fitted.

Probably a compliant magnetic coupling, as even simple force-sensing mechanical hands cost too much to practice back-flips. =3

Why do you think it would be the case about e.g. swapping to thick carpet would throw things off? Intuitively it seems like they must have a tremendous amount of dynamic adjustment going on. For instance think of how much variance, driven by dynamics, that there's going to be in the scene at 2:48 [1] where the robot [intentionally] falls over and then aerobically picks itself back up.

The motion is certainly scripted, but the exact mechanics in play there almost certainly vary radically from take to take. Imagine something simple like a pool/billiards break. Even if you set up a machine to rack the balls and break them in as close to identical as possible, you'd get wildly different results each time. And the dynamics in this motion is going to dwarf that.

[1] - https://youtu.be/mUmlv814aJo?t=168

To be more precise: I think they have a fixed repertoire of moves that they can blend together and slightly tweak on the fly, but only within certain limits.

This would also be normal for human performers - touring ballet companies travel with their own flooring the dancers are used to pirouetting on.

At the 40 second mark every robot does a backflip then when landing hops their supporting leg while pointing the toe of their working leg. Which works fine and looks great! But they arrive in that pose with a certain amount of momentum and needing a certain amount of grip on the floor.

So this is a rehearsed, tested performance - not proof we’ll have firefighter robots doing parkour through burning buildings any time soon!

> To be more precise: I think they have a fixed repertoire of moves that they can blend together and slightly tweak on the fly, but only within certain limits.

Human acrobats do the same, they know a few fixed tricks and practice them often in order to stay in shape. The point here is to compare the dynamic abilities of bots vs those of humans, not vs some pink unicorns - the latter comparison isn't informative because there aren't any jobs for pink unicorns just yet.

> So this is a rehearsed, tested performance - not proof we’ll have firefighter robots doing parkour through burning buildings any time soon!

A bot assisted by humans can do better than them in a burning building, the lack of need for heavy SCBAs would allow the bot to perform acrobatics scripted by a human at the time of action.

> not proof we’ll have firefighter robots doing parkour through burning buildings any time soon!

I wonder how similar friction is across varieties of standard issue corporate carpet...

> They're fast too

That was of of the two things that impressed me most, along with the choreography involving close and direct contact

Smaller platforms are actually harder to build: minimal power budget, weaker drive systems, less sensors, and fewer processing options.

Not a fan of bipedal platforms or 50kg of servos for a number of reasons.

Best regards. =3

Yes and no.

An Aldebaran Nao can fall over with no damage because it’s only 5kg and 58cm. And you can use relatively low power motors, so nobody can lose a finger to crushing in the joints.

But you miss out on the benefits of being able to operate in a human centric world - you’ll never get a Nao to climb stairs, open a door, or carry a cup of coffee.

>Nao can fall over with no damage

They were overpriced, hard to repair, and the university lab would lose one every few weeks. The consumer grade internal ribbon interconnect harness would usually tear eventually.

Those 3kW to 5kW brush-less servos in the biped dance video are often only 12:1 planetary reduction, and are almost certainly backdrivable. As long as the platform has a safe-fall canned pose, than damage should be limited to shear pins in the worst case falls.

Fun to see people pushing the design limits. =3

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