[ODE] sensitivity of ODE to position in space or time

[chris]

Hi, I posted to the sourceforge ode forum but got no answer - maybe
this is the active ode group?

For my Thesis, I had reason to perform a number of identical
experiments with simple variations: displacements in space or time.
One set of experiments was using pyode: dropped a
box near a stationary box onto a plane. I saved an image of the rest
position of the box. The experiment is repeatable: the box lands in
same place each time relative to the stationary one.

Then I moved the whole experiment by (10,10,10) and repeated it. The
box rest position was very different.

I also repeated the first experiment with the only difference being
that I programmed it to wait 8000 seconds before dropping the box.
Again the rest position was difference.

What can anyone say as to the cause of the
sensitivity of ODE to changes in position or time?

Here are links to images and code:

This is an image of the box dropped when at the origin after it comes
to rest (left)
and the same experiment with the boxes and plane displaced by (10,10,10).
http://www.planet-earth.org/pyode/dropBlock0cf10.png

This is an image of the box dropped (at time=20) when at the origin
after it comes to rest (left)
and the same experiment with the right hand box dropped at time=8000.
http://www.planet-earth.org/pyode/dropBlock0cfTime.png

experiment at the origin:
http://www.planet-earth.org/pyode/preciseBlocks.py
displaced by (10,10,10):
http://www.planet-earth.org/pyode/preciseBlocks10.py
at time=8000:
http://www.planet-earth.org/pyode/preciseBlocksTime8000.py

The hardware I was using was a VAIO notebook: intel 770 CPU with
radeon x600 GPU. For python install I followed the steps from Miriam
English:

1. installed python 2.4
python-2.4.3.msi
http://www.python.org/ftp/python/2.4.3/

2. edited autoexec.bat to add:
SET PATH=%PATH%;C:\python
SET PYTHON=C:\PYTHON\

3. installed pyOpenGL
PyOpenGL-2.0.2.01.py2.4-numpy23.exe
http://pyopengl.sourceforge.net

4. Copied glut32.dll to the C:\python\Lib\site-packages\OpenGL
directory. (This is a *crucial* step.)
glut32.dll
http://www.xmission.com/%7Enate/glut.html

5. installed OpenGLContext
OpenGLContext-2.0.0c1.win32-py2.4.exe
http://pyopengl.sourceforge.net/context/
(downloaded from http://pyopengl.sourceforge.net/ )

6. installed PIL (python Image Library)
PIL-1.1.5.win32-py2.4.exe
http://www.pythonware.com/products/pil/

7. installed pyODE
PyODE-1.1.0.win32-py2.4.exe
http://pyode.sourceforge.net/


Now I can double-click on the tutorial3.py from
http://pyode.sourceforge.net/ and it simply runs!


thanks,

chris