Re: CFM, ERP, stepsize, bNormalizationResult failed

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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.

  Bram


On Nov 20, 2007 3:54 PM, <[email protected]> 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
>
> _______________________________________________
> ODE mailing list
> [email protected]
> http://ode.org/mailman/listinfo/ode
>



-- 
Zapp: Captain's log, stardate...er..
Kif: Ohhh. April 13th.
Zapp: April 13th. Point 2.

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Did you try to configure with double precision?<br>Also, smaller dt will improve accuracy.<br>And stability improves when disabling gyroscopic forces.<br>ERP&nbsp; 0.2 seems low to me.<br>Are you sure this is a default?<br>I think ERP is typically close to 1, and CFM is typically close to zero.
<br>If you have a linear or angular motors... increasing Fmax will probably show less constraint violations.<br><br>&nbsp; Bram<br><br><br><div class="gmail_quote">On Nov 20, 2007 3:54 PM,  &lt;<a href="mailto:[email protected]">
[email protected]</a>&gt; wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi,<br>I&#39;m simulating a 6-wheeled mobile robot with a rather complex suspension
<br>mechanism (parallel and closed kinematic loops). I get it to work but only with<br>a &quot;spongy&quot; behavior. I&#39;ve been experimenting with the CFM, ERP and simulation<br>step parameters. The &quot;hardest&quot; constraints I can impose are: ERP=
0.9 and<br>CFM=0.001 at a step size of 0.005.<br>Even if I set ERP to the default 0.2, I can&#39;t get any closer to the default<br>value for CFM (9.9*10^-6). This means that the rover cannot be simulated with<br>default ERP and CFM because l get an error that &quot;bNormalizationResult&quot; failed.
<br>Any ideas?<br>With the current settings the rover is not stable in its initial state, i.e. the<br>suspension is bending under the load of the body even though everything is made<br>of rigid bodies. This indicates to me that ERP and CFM are too &quot;soft&quot;. How can
<br>I fix this problem?<br>Thanks for any help.<br><br>Thomas<br><br>_______________________________________________<br>ODE mailing list<br><a href="mailto:[email protected]">[email protected]</a><br><a href="http://ode.org/mailman/listinfo/ode" target="_blank">
http://ode.org/mailman/listinfo/ode</a><br></blockquote></div><br><br clear="all"><br>-- <br>Zapp: Captain&#39;s log, stardate...er..<br>Kif: Ohhh. April 13th.<br>Zapp: April 13th. Point 2.

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