What makes the ankle exo so effective is its simplicity | Hacker News Reader

What makes the ankle exo so effective is its simplicity

popularmechanics.com

58 pointsrilut29 comments

Fucking. Sweet. I actually wrote this story!!

Also: Everyone should know this. There are still huge issues that need to be figured out before this becomes a commercial product. The 7% figure is bound to change depending on the speed you walk at (diff. speeds will likely require springs with diff. stiffnesses for optimal efficiency). Both Steve and Greg talked about future incarnations that could switch between multiple springs.

...and I didn't write that headline, or the dek (the thing under the head)

Did you get a sense of whether it required tuning to the user? It seems like the ratchet disengaging at the right moment would be quite important to making it comfortable to use.

Well, two thoughts:

One.) At a set, low speed we all walk pretty much the same - at least when it comes to the movements the ratchet was picking up.

Two.) Might be interesting to note that they had a pretty small sample size (n=9), and some people were getting more a benefit than others. I think one participant was up to like 10%.

To do this in full production mode, I would think you would probably make it user tunable.

As the article says, most of it is fairly simple. Just a spring for a cable and a ratchet that moves with the motion of your foot (kind of auto tuned), and grabs the spring.

If the spring was remotely tensible, you could probably just walk and adjust it until it felt best.

You could probably also do that at various speeds and then create a smooth mapping of ensuing parameters for various gaits.

Yes, I think it has to either be tunable or self adjusting. If the ratchet releases early, you are just carrying it around. If the ratchet releases late, I expect it will result in uncomfortable tugging.

So my question is more about the behavior of the implementation, not about the design space for it.

> Also: Everyone should know this.

Hm, OK...then why didn't you include that info in the article?

Because that wouldn't fit the bill of unbridled techno-optimism that is mandatory in (particularly online) popsci/poptech reporting.

Sadly it's also widespread in the scientific literature, as "publish or perish" meets "won't print methods/results that are not said to be awesome".

I think the dek is entirely appropriate. I would call this hacking walking, in the "examine, understand, circumvent" definition of hacking.

Has this system been committed to a modeling package (like COMSOL, for example) so it could be rapidly optimized for particular use cases?

My grandfather was an engineer who suffered from a degenerative muscle disease. This exo bears a resemblance to the brace he wore to hike around the southwestern desert.

CMU Robotics talk on this exo. Includes facts, figures and a lively discussion (75 minutes).: https://www.youtube.com/watch?v=j58ZP7vwcsU

Here's the link for the paper:

Nature: Reducing the energy cost of human walking using an unpowered exoskeleton http://www.nature.com/nature/journal/vaop/ncurrent/full/natu...

I wonder how this compares to trekking poles.

Trekking poles increase your overall metabolic exertion, but make walking feel easier because your whole body (e.g. arms and shoulders) gets thrown into the motion.

They're easier on the legs, harder on the whole body. (Assuming we're talking about trekking across level ground here.)

another nice example of `less is more`.

This was discussed at https://news.ycombinator.com/item?id=9315424. This one is different enough not to be treated as a duplicate, but we did change the title to a more informative sentence from the article.

On the topic of dupes, within HNs Parent relationships, would it be possible to create a meta-dupe tree? Basically, a meta-list above articles that adds dupes (or maybe just closely related) as quasi-children of the "best" or "highest comments" or whatever version of the article. If an article had a parent you could just keep goin up to find the old one.

I'm not sure exactly what UI you have in mind, but yes, we do eventually want to have some kind of related-story grouping.

Some ideas I had about that a couple years ago: https://news.ycombinator.com/item?id=1975950

There exists an amazing device which dramatically increases the efficiency of body-powered locomotion, not to mention speed. However, it is more cumbersome and cannot go to all the same places as an anke exo. This device is called a "bicycle".

I feel like this is a good time to remind you of HN's new guideline to avoid gratuitous negativity. :) Maybe I'm misreading, but you seem to imply that the creators of this device have never heard of a bicycle. Does that add to the discussion?

http://blog.ycombinator.com/new-hacker-news-guideline

Downvoters: I'd appreciate if you would comment as well, since I can't imagine why you would downvote me for reminding someone of our community guidelines.

I haven't downvoted you, but i suspect that those who have have done so because they parse your comment as identifying kazinator's comment as a negative one, and that this identification is mistaken.

I understand. Can you explain why I'm mistaken though? His comment came off as fairly sarcastic to me, and didn't seem to contribute in any way. Surely most of us know what a bicycle is already.

Sorry, i meant that to read "and they believe that this identification is mistaken". I don't understand what gratuitous negativity is, so i don't have an opinion on this myself.

> Downvoters: I'd appreciate if you would comment as well, since I can't imagine why you would downvote me for reminding someone of our community guidelines.

While sometimes necessary, the topic of community guidelines is uninteresting and disruptive to the reason we're here. In this case, IMHO, it isn't necessary to bring up. The GP merely points out that humans have been augmenting our natural locomotion for a long time; that's not a criticism of the developers.

We may have to agree to disagree here. To me, the comment was clearly sarcastic, and therefore negative. I personally did not find the observation that bicycles exist to be interesting at all. Community guidelines may also be uninteresting, but they are important to improving the quality of discussion on HN, while this comment added nothing of value.

"Downvoters: I'd appreciate if you would comment as well, since I can't imagine why you would downvote me for reminding someone of our community guidelines."

Do not discuss your own downvotes. Do not interrupt the actual discussion to meta-discuss the scoring system. Do not address the "downvoters".

Ha, how ironic, not commenting on being downvoted is a community guideline. Thanks for letting me know.

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