[ODE] Car Braking Problem

Jon Watte (ODE) hplus-ode at mindcontrol.org
Tue Jun 28 14:34:52 MST 2005


If you're not setting the fdir1 correctly (and setting the flag in the
contact) then that's almost surely your problem. Carworld, the ODE car
sample application with source, does this; you could grep the source:

http://www.mindcontrol.org/~hplus/carworld/

Cheers,

			/ h+


KuRi wrote:
> Thanks for your answers. It looks (like you say) like a contact problem,
> because with no contacts the problem dissapear. But i don't understand why
> the error depends on the Y Angle of the car. Perhaps it is a round problem.
> Can someone post one example with code of setting the fdir1 to the rolling
> tyre direction, etc...? I have tried that with no results...
> 
> Thanks again. KuRiX
> 
> ----- Original Message ----- 
> From: "Matthew D. Hancher" <mdh at email.arc.nasa.gov>
> To: <ode at q12.org>
> Sent: Monday, June 27, 2005 10:23 PM
> Subject: [ODE] Re: Car Braking Problem
> 
> 
> 
>>>When i brake (dBodyAddTorque), the car turns to the right or to the
>>>left
>>>depending on the Y Axis Angle.
>>
>>Perhaps this is a product of ODE's friction model, which is simplified
>>in ways that make it anisotropic.  You can address this somewhat by
>>cleverly setting the contact's friction direction, rather than letting
>>ODE pick it arbitrarily.  When you generate each contact joint between
>>a wheel and the ground, set the fdir1 field of the dContact structure to
>>be a unit vector that is in the direction of horizontal motion of the
>>wheel geom, and set the dContactFDir1 bit in the contact flags.
>>
>>Matt
>>
>>Matt Hancher
>>Intelligent Systems Division
>>NASA Ames Research Center
>>mdh at email.arc.nasa.gov
>>
>>_______________________________________________
>>ODE mailing list
>>ODE at q12.org
>>http://q12.org/mailman/listinfo/ode
> 
> 
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