Le 20/02/2012 13:34, Tail Kinker a écrit :
> http://youtu.be/brZ6E_TcKeo


Interesting. Nice.

Nevertheless, I still have that disbelieving effect due to instant
acceleration/deceleration of mass: Let split that Mecha in 5 parts:

* torso
* right foot
* left foot
* right arm
* left arm

Movement of a foot, as I perceived it in the animation, is either:
 * not-moving, on the ground
 * moving full speed above the ground

There seems to be an enormous acceleration at the transition points,
which seems unlikely as the feet should weight.
Also, they have no forward/backward tilt, whatever the ground. (on the
second part of the movie, this become visible as the front of the right
foot stay above the ground)

The cycle of each foot seems to be the mirror of the other (not sure,
frame per frame analysis is not easy on youtube). 50% on ground, 50%
moving. I would expect 52% on ground, 48% moving, with a stable transfer
of weight during the 2%.
The movement of each foot should be something like a sin (slow start,
slow end, fast in the middle) in the horizontal direction. On the
vertical direction, it might be a fast or slow or constant speed raise,
but the down part should look like a fall: vertical speed is something
in constant acceleration, vertical position is somehow -y² based
(inverted parabola)

The arms are moving in mirror of the foot, so far so good. Yet I would
wonder about their speed & movement: arms serve two purpose on walk
(maybe more):
 * dynamic equilibrium (keep the centre of mass moving in straight line)
 * reserve of kinetic energy (keep the centre of mass moving without
acceleration)

As the torso is keeping a straight, flat & linear movements, only the
movements of the arms are available to compensate the foot. Check the
mass of legs, their kinetic energy as well as their momentum, and adapt
to the movement of arms (from my point of view, the arm are lighter,
hence moving further than the legs)

Would the arm & leg be the same distance from centre of mass, as well as
same height, the robot could be modeled as a cross of diagonal from an
initial square. The intersection (centre of mass) would move along a
line at regular speed. the ends of each diagonal would be the center of
mass of a leg or an arm. Once you get the position of the intersection,
and the position of each foot, you automatically get the needed position
of each arm.

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