[ODE] physical significance of high mu values?

[Russ Smith]

> I always through friction
> coefficients are supposed to be between 0 and 1.

no - mu is between 1 and infinity. your value of 250
means that the friction normal force must be at least
250 times the contact normal force that supports the
object for the contact to slide. in other words it's
extremely sticky. setting mu=dInfinity will probably
have the same result, and will be computationally
a bit cheaper for the LCP solver.

russ.

--
Russ Smith
http://www.q12.org


> -----Original Message-----
> From: ode-admin@q12.org [mailto:ode-admin@q12.org]On Behalf Of Adam
> Rotaru
> Sent: Thursday, February 28, 2002 9:22 PM
> To: ode@q12.org
> Subject: [ODE] physical significance of high mu values?
> 
> 
> 
>   Howdy,
> 
>   I created a simple human physical model. I try to
> use 
> realistic numbers for units: size in meters, mass in
> kg,
> and -9.8 gravity.  After adjusting some parameters,
> the
> simulation behaves reasonably.
> Here are some values I use: time step 0.025 s (1/40),
> default global CFM&ERP, for joints: ERP=0.4, CFM=1e-4,
> for contacts:
>   contact[i].surface.mode = dContactSoftERP |
> dContactSoftCFM;
>   contact[i].surface.mu = 250.0;
>   contact[i].surface.soft_erp = 0.5;
>   contact[i].surface.soft_cfm = 1e-4;
> 
> Here's my question: the very high mu value of 250 does
> not
> seem physically plausible.  I always through friction
> coefficients are supposed to be between 0 and 1.
> Any explanations?
> --adam
> 
> 
> 
> 
> 
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