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