John Payson wrote:
>
> How do PID-based systems deal with unknown changing characteristics?  For
> example, suppose a robot is supposed to pick up and manipulate objects of
> varying mass, center of gravity, and possibly "inertial oddness" (e.g. a
> closed vessel half-filled with liquid).  From what I understand of PID
> systems, they usually require that the system be tuned for a particular
> amount of intertia, while some circumstances (like the above) require that
> the system work with highly variable (and unknown) inertial effects.

Woah! Good one John! The real world rears it's ugly head and the models,
well, break. That's the real answer. The model is not reality, and we
all know that there's no rules in a knife fight. Just when you think
you're in control, Butch is going to kick you south of the border.

And if you did get him, Sundance would shoot you anyway. -- Tom