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Comment by siekmanj | Hacker News Reader

I could not disagree more with the claim about no improvement in robotic actuators.

The torque density and price of actuators has fallen dramatically since Ben Katz's MIT work on mini cheetah. The actuators on the Unitree G1 based on that work are powerful for their size and near quasi-direct-drive. The motors on the BD E-Atlas are completely passively cooled and appear to have really good torque density. Actuators have never been improving faster than they are now.

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Exactly, the last year or two has been insanely innovative for actuators, with some new material combinations, approaches and multiple startups that are starting to scale up their innovations in this space. Give them a few years to sort out the vaporwares and the robotics revolution will begin.

What innovations specifically?

Can't really name them off the top of my head, sorry!

But if you look up on Google or X, there are multiple companies doing things like pressure based actuators (Clone robotics) or mesh-based knit ones, new forms of EFAM, some new soft actuators and more.

Yeah, these types of actuators are pretty interesting, but I've not seen anything super promising yet.

G1 is a small robot designed for agility, and can't do much real work. That's why it uses lower reduction actuators with low sustained torques, and it'll overheat easily in continuous work. Many of the larger robots (Optimus, Figure, BD Atlas) use higher reduction actuators with strain waves or planetary roller screws. They're designed for higher sustained torques, but are also less agile and less safe for humans to be around. They're also quite heavy (BD Atlas is 90kg), and still can't match human performance.

yes, for heavy lift and bulk manipulation high gear ratios are still necessary. Maybe someday cable drives will be feasible. No question that we are not at human performance yet or that there isn't a ways to go. This is the specific claim I was arguing against:

> There has been no innovation in robotic actuators since Honda's Asimo.

I believe we are 100% making tangible progress and the technology is improving faster than it ever has.

I don't think electric motors + reduction gears can be improved much, unless I'm missing something. I hope someone invents something completely new.

Judging from recent improvement it doesn't appear to be a dead end technology, but I guess time will tell!

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