[ODE] Friction problems & Donating Sample Code to ODE

[Rob Leclerc]

Friction Problems
==================
I am working on some code to evolve a neural network to control the
movements of a simple dog like body. Unfortunately, it looks like I
might be having some difficulties with friction, as the best evolved
creature looks like he is trying to move on an ice rink!

I am using the piece of code below for the CD, which I grabbed from one
of the examples. I had thought that setting surface.mu = dInfinity would
have worked, but it doesn't seem to be doing what I want it to. To be
honest, I don't know all the physics that well and I was hoping that
maybe someone might know how I can get over this problem. (Code Below)

Donating Sample Code to ODE project
===================================
Ironically, I had problems putting this model together in CM Labs,
Vortex; there were some major instabilities that I couldn't get worked
out and tech support has been looking at it for a week now without much
luck apparently. Kudos to ODE, since I think I am pretty close to
getting this working in only a couple of days, and thanks for everyone
for their help so far.  Anyway, this is a project for a grad course I am
doing and I am basically generating a life-like skeleton to put an
"implicit surface" in order to get a nice life-like body. Anyway, I was
wondering if there was someone I could donate this code to, for the ODE
project once everything is worked out (I am almost done). Basically, the
code creates a dog like creature and evolves the weights of a neural
network to get it to move. I thought it might be useful for anyone
interested in doing virtual creature modeling. 


/** Code I am using for CD **/
static void nearCallback (void *data, dGeomID o1, dGeomID o2)
{
    int i;
    // exit without doing anything if the two bodies are connected by a
joint
    dBodyID b1 = dGeomGetBody(o1);
    dBodyID b2 = dGeomGetBody(o2);
    if (b1 && b2 && dAreConnectedExcluding (b1,b2,dJointTypeContact)) 
    {   return;
    }

    dContact contact[4];			// up to 4 contacts per
box-box
    for (i=0; i<4; i++) {
        contact[i].surface.mode = dContactBounce | dContactSoftCFM;
        contact[i].surface.mu = dInfinity;
        contact[i].surface.mu2 = dInfinity;
        contact[i].surface.bounce = 0.1;
        contact[i].surface.bounce_vel = 0.1;
        contact[i].surface.soft_cfm = 0.01;
    }
    if (int numc = dCollide (o1,o2,4,&contact[0].geom,sizeof(dContact)))
{
        dMatrix3 RI;
        dRSetIdentity (RI);
        const dReal ss[3] = {0.02,0.02,0.02};
        for (i=0; i<numc; i++) {
            dJointID c = dJointCreateContact
(world,contactgroup,contact+i);
            dJointAttach (c,b1,b2);
        }
    }
}


==============================
Rob Leclerc
University of Calgary
Department of Computer Science
Office: ICT 728
==============================