I was staring at my racers (light-weight running cleats) when a thought hit me. Most running shoes have an upwards curve at the toe because humans naturally “roll” when they run. Humans naturally push off of the ground with our toes; the curve gives the toes the leverage that they need much in the same way that a fulcrum gives a board leverage.
In the martial artists’ realm, “on your toes” is the typical phrase for the aggressive position (feet spread wide appart, knees and elbows bent, head up, chin tucked, and body ballanced on your toes). This position shifts the weight of your body onto the balls of your feet and lowers and spreads your COG greatly. If this is hard to picture, visualize the stance that a line-backer is in just before he is going to get hit by an opposing line-man.
The aggressive position is universally viable stance because it is so easy to transition to an attack or a defense from it.
So, when I was sketching the fighting stance for my biped, I realized that such a stance was not fully possible because the biped does not have “toes”, per se. Jim, could you make a set of robot feet that have about a 45 degree bend? The “toe” portion itself would only have to be about a third of the size of the total foot length.
A “toe” would also be nice because it would make the gait of the biped more natural and quite a bit longer. (If you’d like to understand how I came to that conclusion, take the largest step that you can while keeping both of your feet flat on the ground. Then take the largest step that you can and allow the back foot to go up on it’s toe.)
Interesting idea. It’s got me wondering if maybe the whole foot should have a gradual curve to it to smooth out the weight shift is the robot moves forward.
Hey Nick, I’ve seen it done on a Robo-One before. It’s a cool idea. The one I saw had a hinge on the toe section of the foot. While I’m sure it has some advantages it also requires a more complex walking program. The flat foot you see on 99% of Robo-Ones are more stable, and lets face it, this is already challanging enough. I think I’ll pass on the hinged foot for now, as I consider it to be useful only for advanced builders.
I seem to have an affinity for counting, sorting, color-coding, pre-arranging marriages, and planning burials for my chickens before they hatch.
Perhaps I should wait until I actually get my hands on your new biped in mid-December before I start planning extraneous devices.
Then again, extra foresight rarely hurts. So, in keeping with that motto, I’ve forseen another possible “toe”.
Instead of a servo-driven hinge or the simple bend in the metal that I thought of, we could use a passive hinge with a relatively high-tension spring. The spring would have to have an adjustable tension, though. Then we could get the rolling action that I was talking about without sacrificing too much of the superior balance that standard feet give.
Nate, I thought your idea was on until I realized that a gradual curve allong the whole feet would sacrifice the normal balance. And, if we were to curve just the toe portion, we would be sacrificing the balance of the bot when it was standing on its toes.
I like the high-tension hinge idea because it combines that smooth transition that you wanted with the stability of flat surfaces.
Anyhow, don’t worry about making anything in the near future for this, Jim. I was just throwing out ideas for you to put on the back burner.