[ODE] Cube and rectangular box reacting differently to torque

[Jaap Stolk]

On 4/17/06, Devrim Erdem <devrim.erdem at gmail.com> wrote:
> The box is rectangular. It's dimensions are xyz=[1,5,1]
>
> I am not sure about the theory you've mentioned, if somebody could
> point to a name for this theory, I'd appreciate.
>
> But I think it is still unclear why the body is going backward and
> forward between two different directions of rotations.

Took a bit of searching to find the correct English word, but it's like a
"spinning top" (toy)
You can start spinning it on it's side, and it will move its axes of
rotation towards the
axes with the lowest moment of inertia, and effectively ending up
spinning in the way you normally would spin a "spinning top". It is
even possible that the center of mass of the "spinning top" ends up
higher. the energy needed to do this comes from the energy that is
saved because the rotation around the new axes requires less energy.

In your case, the object should end up spinning around the y-ax (and
stay like that, not change back to something else as you mentioned)

Or it could just be an accumulation of errors :-)
I don't know exactly how ODE simulates this, and I think I read
somewhere that ODE objects can sometimes start rotating faster and
faster because of some compensation in the simulation gets the
overhand...

Jaap.