[ODE] Differentials and such

[Tom De Muer]

> "Tom De Muer" <tom.demuer at skynet.be> skreiv:
> > I think I have not expressed myself very clearly :-/   What I mean is
that
> > after you set the torque to the wheels, your wheels will have some
speed.
> > That speed needs to get feeded back to the engine to determine it's new
RPM.
>
> Yes, but what if... you jump, and in the air the engine goes back to
> idle. OR you suddenly downshift... i.e. engine braking and
> engine/drivetrain inertia isn't fed back to the wheels again. This would
> be very difficult in ODE in my opinion, as you'd only be able to feed
> the torque one way per timestep... you could alternate, but I doubt it
> would work very well.

This is how I do it now is when you have engine braking: set Vel to 0.0 and
set FMax as the torque created by the engine braking.  You are right that
the inertia of the engine/drivetrain is not taken into account then.  What
are the thoughts on this: propel a flywheel with the engine and use the
generated torque of that one to propel the transmission?

> What would be really great would be a differential joint! Or rather,
> just some way to set the pinion input FMax and Vel (or just add torque
> to it), which keeps the relationship in angle like this:
> pinion=ratio*(w1+w2)/2 where w1 and w2 is the angle of the wheels (angle
> can be rotational velocity instead). Does anyone know how the Amotor
> finds out how much torque it needs to set the desired speed? Guess I'll
> have to take a deep dive into the ODE sources, any hints and ideas are
> appreciated!

While you are busy: a double whishbone joint would be nice too ;o)
Currently I'm thinking of building such a joint but the constraints seem
impossible to put in a clean formula.  I would be very interesting in your
progress on a differential joint :)  A proper differiential like a limited
slip differiential would be awesome too!

Cheers!
Tom

> -- 
> Amund Børsand <amund £ offroad . no>
>