[ODE] unstable objects and the documentation

[DjA]

Regarding stable simulations. What is the recommended size/density/mass of
objects?

I've been told that the maximum size should be around 1, and that your
universe should be around 0,0,0, as the solver needs to use the integer part
of the number for multiplying in, hence small = good. (I noticed this when I
realised the demo_buggy was TINY, a few centimetres long, next to my
'enormous' 3 metre car :)

I'm under the impression that the average density should be around one
(let's say 0.1 to 10.0) and both of those naturally lead to a mass of
'about' 1.0.

Am I correct in these assumptions? My only real issue with that is that a
gravity of -9.7 is next to useless, as car-sized objects end up 0.3 units
long, and thus gravity goes up to -97.0, to compensate.

----- Original Message ----- 
From: "Nate W" <coding@natew.com>
To: "ODE List" <ode@q12.org>
Sent: Wednesday, June 25, 2003 1:34 AM
Subject: Re: [ODE] unstable objects


> On Tue, 24 Jun 2003, Todd Wasson wrote:
>
> > I'm having some issues with object instability in a program I'm working
> > on, using ODE.
>
> There's a little bit of information about this in the user guide, but it's
> "just notes for now."
>
> http://opende.sourceforge.net/ode-latest-userguide.html#ref85
>
> I just added a page to the Wiki FAQ, too:
>
> http://q12.org/cgi-bin/wiki.pl?MakingStableSimulations
>
> And as regards your particular situation, can you replace the 'large box'
> you're using for a ground, with a plane?  That will probably clear up the
> odd contact joints that you're seeing.  When two boxes rest face-to-face,
> it often (always?) takes three contact joints to hold them stable.
> Having contact joints in odd places sounds bad, but I'm pretty sure that
> culling joints is at least as bad, if not worse.
>
> -- 
>
> Nate Waddoups
> Redmond WA USA
> http://www.natew.com
>
>
>
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