[ODE] CFM, ERP, stepsize, bNormalizationResult failed

Bram Stolk b.stolk at gmail.com
Tue Nov 20 17:47:32 MST 2007

Did you try to configure with double precision?
Also, smaller dt will improve accuracy.
And stability improves when disabling gyroscopic forces.
ERP  0.2 seems low to me.
Are you sure this is a default?
I think ERP is typically close to 1, and CFM is typically close to zero.
If you have a linear or angular motors... increasing Fmax will probably show
less constraint violations.


On Nov 20, 2007 3:54 PM, <ode at thoemsen.ch> wrote:

> Hi,
> I'm simulating a 6-wheeled mobile robot with a rather complex suspension
> mechanism (parallel and closed kinematic loops). I get it to work but only
> with
> a "spongy" behavior. I've been experimenting with the CFM, ERP and
> simulation
> step parameters. The "hardest" constraints I can impose are: ERP=0.9 and
> CFM=0.001 at a step size of 0.005.
> Even if I set ERP to the default 0.2, I can't get any closer to the
> default
> value for CFM (9.9*10^-6). This means that the rover cannot be simulated
> with
> default ERP and CFM because l get an error that "bNormalizationResult"
> failed.
> Any ideas?
> With the current settings the rover is not stable in its initial state,
> i.e. the
> suspension is bending under the load of the body even though everything is
> made
> of rigid bodies. This indicates to me that ERP and CFM are too "soft". How
> can
> I fix this problem?
> Thanks for any help.
> Thomas
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