joreilly

I can't give an answer which would pass a proper roboticist without them wrinkling their nose, but my guess is that rotary actuators are more simple and space efficient to implement, and can generate the necessary high torques for these systems.

When using a linear actuator, you need to offset it from the joint so that it generates torque (that's part of the reason we have kneecaps, actually; it increases the distance between the centre of rotation of our knee and where our leg muscles are actually pulling from, increasing the output torque). This involves more mechanical complexity in the design compared to rotary actuators, which can just be slapped onto the joint directly. That offset also takes up space, so your system is now less compact.

None of the heavier legged robots I know of use direct drive actuators; ANYmal uses Series Elastic Actuators, MIT Cheetah and (maybe) Boston Dynamics Spot use Quasi-Direct Drive actuators with a low gear ratio gearbox (sub-10:1, I believe), RealHyQ uses hydraulic actuators. Electric actuators simply can't output the amount of torque these systems need to carry themselves around, so they need some form of gearing. The linked actuators you shared are direct driven, so they would need some gearing on their output. I had trouble finding anything about gearing direct drive linear actuators, which leads me to believe it's not really a thing, because if you need high loads, you'll jump to geared linear actuators, which are really just rotary actuators with a belt or rack and pinion!

Aside from the mechanical challenges associated with using a linear actuator setup, it's (to my knowledge) not necessarily better to follow biology when it comes to robots. Wheeled robots can move faster on flat terrain than any animal, so legs aren't ideal when you have access to gas-powered engines or electric actuators. Airplanes with turbines can carry much heavier loads than birds because flapping wings just doesn't scale up to the weight of a jumbo jet with luggage and passengers. Legged robots are actually more energy efficient when they don't try mimicking an animal's gait because they don't have organic muscles arranged in the same way. Any finally, rotary actuators are a better choice than linear actuators (for now) because we don't have hyper-compact, super torque-dense linear actuators that can match our muscles.

This isn't to say that biologically inspired designs can't be better, and there's a lot of research into finding ways of replicating the natural properties of certain materials, such as the strength of silk or hardness of the shells of some crustaceans. But in the end, with the technology we have, rotary actuators provide better torque density, and a more compact and simple design than linear actuators.

[1]: I didn't cite anything here because of time constraints, but it's an amalgamation of half-forgotten knowledge from some research I've done on the topic of legged robots

I've written a similar guide that goes into a bit more detail, such as setting up S3-compatible object storage as the primary storage, using a custom domain name, etc.:

[link redacted]

I've enjoyed using Nextcloud so far. Download and upload speeds seem better than my previous cloud provider, despite using the cheapest node available. Having my Notes, Calendar, and Deck all available on the same platform is nice too. It's great having a cloud that isn't chock full of dark patterns; the only thing I've found similar so far with Nextcloud is the server branding at the bottom, which, as you detailed, can be removed.

From the article:

> In her suit, Viola acknowledged writing most of the posts. But she denied being behind the anti-Muslim screed. That was critical to Sorokin’s decision to allow the libel and defamation part of Viola’s suit to proceed. The former professor “has plausibly alleged that Benton may have been negligent in his failure to verify that she was the author,” the judge wrote.

If she can prove that it wasn't her/Benton can't prove that it was her (I'm not familiar with the legal system, so I don't know which it would be), then there would indeed be an untrue statement. As for damage; why does anyone dredge up another's darker side, if not to damage them in some way? I can't think of another motive for doing so.

> Reminds me of how one day, I think in SF, I was trying to go around without reading things and just realized there are so many things shouting at me with words, especially billboards and other forms of public advertising. I would love to even have a city here in the US experiment with something like this.

I'm in the exact same position, I'd love to see a large-scale experiment to determine the economic and psychological impact of removing public advertising, or at least reducing it to a more "comfortable" level, whatever that may be. The Canadian government experimented a bit with universal basic income in the 70s, and more again recently with COVID, so perhaps they'd be willing to give this a shot as well.

> I would, too, especially as a consumer, and yet, as a producer, I wonder how annoyed I would be without ads. Maybe there's a balance, and I believe needs to be have more consumer voice, and less producer voice.

Another concern/shortcoming I forgot to address above is what companies will do to get their products out there; will advertising take a more subtle, perverse tone if they're not allowed billboards and banner ads? Perhaps a middle-ground will stop a more covert extreme from appearing. Perhaps I'm falling for the middle ground fallacy.

I added a link to my website in my profile, my email is on there. Cheers!