[ODE] Simulating a bobsleigh

David Ramos dramos at cyanide-studio.com
Thu Aug 4 10:15:20 MST 2005

Good advices,

Michael, Megan, Jon,
Got what I wanted :)
dContactApprox1 , mu2 and slip2 are the key, thanks guys.
No more wheels or traction force.

You are right, I experiment some strange behavior with boxes, some
 inexpected "jumps" etc.. despite a good global sensation.
What's exactly the problem ? Any fix expected ?

Using cylinders for the skates tends to make the bobsleigh rolling
despite my effort to lower the Center of Mass, the mass of the bob and
to increase the mass of the skates.

Using rays seems to give exactly the opposite...very hard to roll :)

I need a compromise because both behaviors are expected in bobsleigh.

 thanks for your help,

> ----- Original Message ----- 
> From: "Jon Watte (ODE)" <hplus-ode at mindcontrol.org>
> To: "David Ramos" <dramos at cyanide-studio.com>
> Cc: <ode at q12.org>
> Sent: Monday, August 01, 2005 6:43 PM
> Subject: Re: [ODE] Simulating a bobsleigh
>> Did you turn on dContactApprox1 for the contacts? If not, then "mu" is 
>> really a force limit, which is usually not what you want.
>> Also, I'm not sure that you want boxes, because those will have nasty 
>> behavior when running over rough terrain, along the edges. I'd probably 
>> use ccylinders, or possibly just a ray per skate, and doctor the contacts 
>> to use fDir, and have a high friction sideways, and low friction 
>> lengthways.
>> Cheers,
>>           / h+
>> David Ramos wrote:
>>> Hi,
>>>  I'm trying to setup a bobsleigh :
>>> a box for the chassis, and 4 hinged-boxes for the skates.
>>>  The problem is that this configuration makes the bob to behave a little 
>>> like an hovercraft. I don't have much control.
>>>  mu is set to a low value (0.0015f) to make the bob sliding but the 
>>> skates don't have
>>> any grip. Playing with slip values doesn't give me better results.
>>>  On the other side, setting mu to a higher friction asks me to add some 
>>> traction force simulated with hinge2 joints and spheres for the wheels. 
>>> So I end up with a car :) Not the result expected....
>>>  an hybrid approach with traction for the rear wheels and skates for the
>>> front wheels is not better...
>>>  Some ideas on how to model that kind of behavior ?
>>>  Thanks,
>>> David
>>> ------------------------------------------------------------------------
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