[ODE] Steering and rolling wheels

[Sergio Casas Yrurzum]

> Hi Sergio,
>
> I don't know why you get strange results when steering and rolling at the
same time. But I did notice you saying that you >use dAddRelTorque to power
the joints. I thought it might be 'safer' to use the dJointSetHingeParam to
do that (with >dParamFMax and dParamVel).

You're right. I've tried it and it works better. Not perfect, but better.
Thanks.

>Also, do you really need the two rear wheels to steer? If the front wheel
(the sphere on >the >ball/socket) can rotate in >any direction, then
steering can be accomplished by varying the relative speeds of the rear
>wheel rotations.

Yes, I know that, but I need the rear wheels to steer. This is not something
I can change (I don't make that kind of decisions), though I know you're
absolutely right.

> About the strange jumping of your robot, the only thing I could guess at
was that it has something to do with how ODE >calculates friction, or
perhaps it's an oddity about how the wheel collides with the floor when you
'roll' and 'steer' at the >same time.
>
> Well, I hope this was of any value to you.
> Greets,
> Mark

Thanks, Mark.