[ODE] Setting up two objects with two seperate centre of gravities

[Tristan McMillan]

Hi

Sorry, but I left out two lines after the code where I assign the geom,
mBodyBox to the Body ,mBody and then I assign the mass to that body i.e:

dGeomSetBody ( mBodyBox , mBody );
dBodySetMass ( mBody , &mM );

So doesn't that link the mass to the body and its geometry.

Regards,
Tristan

On Wed, 2006-09-13 at 09:14 -0700, Jon Watte (ODE) wrote:
> You're not actually assigning the mass to the body in that code.
> 
> Cheers,
> 
>           / h+
> 
> 
> Tristan McMillan wrote:
> > Hi ODE Community
> >
> > This question has had me stumped for quit a while now.
> >
> > What I'm trying to do is create a truck and trailer combination. So I've
> > created two bodies:
> > 1) Body 1 is connected to a Trimesh geometry which represents the horse
> > 2) Body 2 is just a box.
> >
> > However the problem comes when I try to setup the mass and inertias of
> > each body.
> >
> > I currently do this using the following function.
> > Horse (Trimesh):
> >
> > dBodySetPosition( horseBody, horseCG[0], horseCG[1], horseCG[2] ); 
> > dMassSetParameters(&mM,mass,CG[0],CG[1],CG[2],Ix,Iy,Iz,0.0,0.0,0.0); 
> >
> > Trailer (Box)
> >
> > dBodySetPosition( trailerBody,trailerCG[0],trailerCG[1],trailerCG[2] );
> > dMassSetBox( &mM, DENSITY, length,width,height);
> >
> > Where the CG positions are all relative to a global reference system. 
> >
> > This however always gives an error for the horse setup:
> >
> > ODE Message 2: center of mass inconsistent with mass parameters in
> > dMassCheck() File mass.cpp Line 68
> >
> > ODE Message 2: center of mass inconsistent with mass parameters in
> > dMassCheck() File mass.cpp Line 68
> >
> > Is this the right way to set the mass of a trimesh body?
> >
> > I've checked the wiki and found that the cg of each body should always
> > be at the origin, but then how do you place the other body (trailer)
> > relative to this?
> >
> > BTW: The trailer is connected to the horse using a universal joint.
> >
> > Thanks
> > Tristan
> >
> >
> >
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> > ODE at q12.org
> > http://q12.org/mailman/listinfo/ode
> >
> >
> >   
> 
>