[ODE] three-body joints

[Amund Børsand]

A differential would be useful, but maybe not as a joint. The third part
is the axle. But this would only be useful for modelling live rear drive
axles. What about other types of suspension, or front drive axles? It
would be nice to have some sort of equation/restraint based on Amotors,
that the solver can solve. But I haven't figured out how to yet.

Amund


"Alen Ladavac" <alenl-ml at croteam.com> skreiv:

> If it's only about the differential, you should probably implement it as a
> two body joint. As I understand it, the third body here (motor) is not
> really a body in a usual simulation. I mean, you don't actually model the
> engine, transmission, etc. directly with bodies and joints, do you? ;) Or do
> you need differential joint for something other than powering a car?
> 
> Alen
> 
> ----- Original Message -----
> From: "Gary R. Van Sickle" <g.r.vansickle at worldnet.att.net>
> To: <ode at q12.org>
> Sent: Friday, September 10, 2004 01:49
> Subject: RE: [ODE] three-body joints
> 
> 
> > > Hi everybody.  I'm wondering, what are the design issues that
> > > caused Russ to implement only two-body joints?  It seems to
> > > me that, from the point of view of the "big matrix", it's
> > > just as easy to implement n-body joints.  For example, the
> > > differentials used in cars can only be implemented as 3-body
> > > joints.  No combination of 2-body joints will do.
> >
> > Really?  I'm having a hard time coming up with a reason why; can you
> explain
> > further (or point me to a links)?
> >
> > >  The equations for a differential are in the form e.g. c1 wA + c2 wB +
> > > c3 wC = 0, for bodies A, B, C.  What would it take to add
> > > n-body joint support?
> >
> > Somebody to code it up and maintain it.  I can't speak for Russ, but I'm
> > sure if it fit in well and was truly useful it would have a pretty fair
> > chance of at least getting into "contrib".
> >
> > --
> > Gary R. Van Sickle
> >
> >
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> >
> 
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-- 
Amund Børsand <amund £ offroad . no>