[ODE] redundant constrain problems?

[Graham Fyffe]

Hi gang.  I have noticed various problems arising from having
redundant constraints in my joint setups.  My limited understanding of
WorldStep tells me that this has to do with having the number of
unconstrained variables pretty much hard coded into the joint classes.
 This basically pushes the burden of figuring out how many
unconstrained variables are in the whole system onto the user, who has
to be very careful about making accidentally redundant constraints.

The results that I'm seeing with redundant constraints on my car
suspension is that the car will lift into the air and the whole
chassis will begin to roll left-over-right, as if some large external
torque were being applied to it.  This problem goes away if I tweak my
joint configuration a little bit, but this is unstable at best when
the user has the freedom to make suspension adjustments :P

Especially aggravating would be a joint system without redundant
constraints that is manipulated in such a way as to have redundant
constraints.  I'm not sure if this can ever really happen.

So, what I'm getting at, is there any way to modify WorldStep so that
it doesn't rely on the info from the joints about how many
unconstrained variables there are, and instead directly calculate it
from the constraint matrix?  Or is this just way too expensive?

Thanks everybody!

- Graham