Mechanical Work

Sparkstation...... great answer.

I found your engineering terminology "The design of the kangaroo" interesting.

I would give you a GA but i think you still need some challenges in life so I will let you tick along on 8.

Just 2 minor points. Some horses and ponies actually use a lateral gait, icelandics do it and a number of others. It appears to be genetically linked as some animals find it easier than others and it can be bred for, (though they may just learn from watching mum) but apparently the military desired a trot, ie working diagonals so bred away from the lateral pace. But i am fascinated that the lateral pace is more fuel efficient and would like to know where to find more info on the subject.

The second point I want to mention is that there is a study underway looking at the gait of the elderly and comparing it with penguins. Apparently there are some major benefits in balance in (I think) training the elderly to walk like penguins.

Neither of these points detract from a really good answer.

Simon

I don't know of a good free link to give you, but you might try searching on gait energetics and adding inverted pendulum if needed as a filter. There's no quick and simple answer. But, I can tell you to not use only the concept of mechanical work (Fd) when dealing with physiology.

If you observe a penguin waddling, you will note that he picks up his foot, advances it forward and then seemingly "falls" forward to move along. That is taking advantage of the gravitational forces. Then, as his step continues, he is actually appearing to fall forwaord with each advancing step. That is the kinetic energy being utilized. As he "falls" forward, he is not actually using his energy to move ahead, it is the combination of the kinetic energy and the gravitational energy that propels him. Very novel idea. He walks and advances, but with very little of his own energy expended. The biggest expenditure of energy comes in the act of lifting his foot off the ground.

nzur

Here's a link that shows different gaits and some of the math.

http://s.i-techonline.com/Book/Humanoid-Robots-Human-like-Machines/ISBN978-3-902613-07-3mrmi11.pdf

It's very nice of you to show this link...

Thank you very much TVP45 !!

"...How the muscular work can be reduced if gravitational energy and kinetic energy are exchanged ?..."

Bipedal walking is an excellent example:

In bipedal walking, say, a man, you in fact tip yourself off-balance forward with one leg, and catch yourself back into a momentary balance with the other foot. This is one step of course, while in actual, continuous, walking, this one-cycle is repetitive.

in tipping yourself off balance yo convert your existing forward motion (kinetic energy) into some sort of "falling", which is now transferred to gravitational energy taking place.

Now, you don't allow yourself to fall all the way to the ground (oops!) but instead, you send the other leg (opposite to the tipping leg) forward to sort of "Catch" the falling body, and while using it as a stilt, you tip your center of gravity over it, thus transferring your potential energy back from gravitational "fall" into (kinetic) forward motion again.

This re-cyclic motion, reduces the chemical energy produced by you muscles to maintain your movement, by replacing some of kinetic energy produced by your muscles burning calories, with the constant 1G available for "Free-Falling" as well as some load-barring of using your leg bones as a stilt - to bridge over that tipping - in order to move forward ready for the next "Fall".

This load creates pressure, which in turn, dissipates as heat.

http://www.mme.fiu.edu/robotics/elib/Clyon-Robust%20Bipedal%20Humanoid%20Robot.pdf