[ODE] Brakes and rotational damping

[Matthew Harmon]

Hi all:

What is a good scheme for applying “brakes” or other damping to a rotating
body?  We’ve tried a few things but would love some recommendations:

  - Velocity-Based Damping: Grab the angular velocity, reduce it, and put it
back.  This is easy, avoids “backlash”, but probably isn’t kosher and I
imagine may result in non-physical behavior in ODE.  However, this is “sort
of” how brakes behave – they simply reduce any existing rotational velocity.

  - Add “counter-torque”: Apply a torque opposing the current angle of
rotation.  This works, but has the “backlash” problem where applying too
much torque will cause the body to reverse it’s spin.  We check for backlash
and “lock” the body if it switches direction
 but this feels a little like a
hack.

  - Add a contact friction joint: This seems to be the most realistic model,
but probably overkill.  Since, I believe, ODE simply adds little forces for
contact joints, it may have a “backlash” effect also.

Any recommendations or best practices here?
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