Gyroscopic/Self balancing Mechanical Ankle Joint

[Warbadger]

Hello. This is the first post on this site I'm making outside of the "New member welcome" part, and I intend on getting right down to why I'm here:

I would like to know of any possible designs or methods by which to build a mechanical ankle joint capable of holding at least 500 US pounds, and balancing itself in such a way that it would be possible to attach such a thing to the bottom of say, a stilt, and it would would be capable of simulating the human ankle's lateral flexibility as well as the normal "Heel/Toe" movement. This seems to be a reasonable place to ask about something like this, or if it's even valid mechanically, as I am not very knowledgeable in this field.

This is for a personal project of mine, and I would very much like the help of people who know more about mechanics than me. Feel free to ask for more information if necessary, and I will provide you with it so long as it's actually reasonable. Thank you.

 

[Mech_Engineer]

It seems like most of what you're talking about should be possible. Lateral flexibility cold be achieved using a joint of some kind, heel-toe is harder to define and kind of depends on what you're after (powered vs. unpowered). Have you done any research on prosthetic legs and their designs?

 

[Warbadger]

It seems like most of what you're talking about should be possible. Lateral flexibility cold be achieved using a joint of some kind, heel-toe is harder to define and kind of depends on what you're after (powered vs. unpowered). Have you done any research on prosthetic legs and their designs?

I've done a little bit, since it was the first thing that came to mind. From what I understand, a lot of prosthetics don't concern themselves with the range of motion I'm looking for yet, since they're still working on making the foot react correctly in terms of balance and movement. I very well probably missed something though, I didn't look into it as hard as I should have.

As for the joint, that was kind of what I was thinking, but I am unsure as to how to implement such a thing correctly. The first thing I thought of was a ball joint with elastic (or other similar substance) straps or bands pulling the foot of the device back into a neutral position when it was airborne (i.e. when taking a step) so as to make it capable of conforming to the shape of the ground it was placed upon with each step, or be capable of standing with the bottom of the foot flat on the ground even if the leg was held at an angle. The problem with this design, is that I don't think it could actually support the kind of weight I'm looking for it to, or for the elastic to be strong enough to work properly.

This led me to the idea of using pneumatics or some other similar mechanical device to achieve the return to neutral, but that then begs the question of how to power such a thing, not to mention bringing the danger of pneumatic systems close to the human body (I understand that if such devices malfunction they can be quite deadly, and that pneumatic fluid is capable of puncturing human skin if it leaks, requiring hospitalization). I'm willing to work out the power issue at a later point, but this leaves the other problems.

EDIT: I was thinking of Hydraulic fluid, silly me. Pneumatic is gas cylinders. Perhaps pneumatics might be more valid than I thought...

 

[Mech_Engineer]

I think the secret will be simplicity, especially where weight is concerned. You might read up on some prosthetic leg/ankle designs for inspiration...