[ODE] no help :(

[david@csworkbench.com]

It's a known problem that bodies rotating in space without gravity or
anything to slow them down will gain energy until they explode, but that
doesn't sound like what you're simulating (lying on the ground)....  I'm
not sure I understand why your simulation is moving at all if you just
have two bodies connected by a hinge with angle limits set to 0.  However,
if you are applying power against those limits, then there's your problem.
 ODE adds the maximum joint force to keep a powered joint from getting
past it's limit... which could be where your extra energy is coming from. 
If you aren't powering through that limit, then I'm not sure I understand
what your simulation is doing.  Perhaps a video (if you're using drawstuff
it can output the frames in ppm format, you can convert with ffmpeg on
Linux, not sure on other platforms) would help to illustrate it better.

David

> Hello everybody!
>
> Unfortunatelly nobody answered to my question I wrote last week. I
> analysed  my problem of an exploding sphere rotation in ODE. I think,
> there must be an  error or instable approximation in the calculation of
> rotating spheres. Please may anybody give me a feed back, whether I am
> wrong or not:
>
> a) if you create a sphere (lying on the ground) and if you then connect
> it to  another body decentrally (e.g. also a sphere) via joint (whereby
> the joint  should be fixt e.g. by setting the stop-parameters of a hinge
> angle to 0),  after starting the simulation the second body will behave
> like a pendular,  but increase its pendular height more and more until
> it "exploses".
>
> b) even if the mass is negative the same problem occurs
>
> c) the mass of both bodies is independant from the wrong behavior we can
> see
>
> Why does this phenomenom occur? How can I correct it?
>
> Please, may anybody help me?
>
> Thank
>  Björn Mahn.
> --
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