Ok I am now working on the limits, hope I can get it today, there are some tricks that need to be resolved but I hope is not a big problem.
Sweeney, on this
Sweenie wrote:How will the kinematic controller for the body be handled? Do you have to calculate the position for the body controller based on the midpoint for each leg?
I suppose you calculate a midpoint based on all feet positions and then allow some limited linear movement to make the body move up/down , back/forth and sideways.
Now that we can see where we are going with this, you can see how the body can move independent of the feet, you can see that all those explanations that people has come up in the pass 20 to 25 years since they try to animate objects with pure IK are just special cases of more general solutions.
These trick of averaging a position based of the location of other positions work only because there are part of the general IK solution. we can use that of course, but I expect a lot better or I will consider the effort a failure.
The problem with those thicks, is that the make the animation look robotic and for good reason.
Then the same people who come up with the trick tell you that IK animation look robotic.
https://www.youtube.com/watch?v=QdQL11uWWcII really believe that teh system we are developing now can make Asimo walk like a real human being not like these pathetic robot sequences that we see in the video.
It is my contention that biological locomotion is not as difficult as people think it is. if you think about every living creature that is not a plant has independently evolved a way of locomotion.
we see locomotion with not leg (some reptiles and bacteria), with one leg (the flagellum), with tow legs, with four legs, and with 6 or more legs, even with hundred of legs)
This is telling me that locomotion is not really that complicated.
I also put it there that biped locomotion is way simpler than quadruped, six or more leg locomotion.
the reason I say this is that a biped locomotion has no closed loop since a biped walk really keep both legs on the ground only when resting.
Multiple limbs locomotion is in full on kinematic loop that needs to be resolved perpetually weather these is a biological brain of a digital CPU, a lot of resourses has to be dedicate to calculate the balanced of these loops.
you can see this in the evolution of predator dinosaurs, as they become more intelligent they the traded walking on four leg for walking in two legs.
even today quadruped predators like tigers and cheetahs gallop in two legs when they chase a pray. that's just me speculation and observation.
what I think is that biological locomotion works similar to the way the system we are now developing works. there is a brute force system that is in charge of controlling the limbs, this system is the one that convert desired location to muscle tension and it works by trial and error. so it does not need high level programming, just instinct.
you can see this even on dead animals, the nervous system still react to stimulus even after the animal is dead. In our system this is represented by the physic system.
Then there is another high level system that learn some sequences of motions and this is like a neural net that can be programmed by examples and can even modify its programing. but for these to be effective it needs reproducibility and the only way, in my option to get that is by working on the geometry of the system ignoring the physics of the system.
it will be impossible to program a walk cycle by storing muscle forces because muscle forces varies hugely with the environment, on the other hand is easy to store the sequence and add small variation to adapt to the environment.
so to conclude my rant and speculations, I believe all the mombojumbo we has learned in the pass 25 years is just, or at best a special case of a solution that work on a very narrow range.