Bathtubs; feedforward

[From Bill Powers (930119.2200)]

If I used all the ice and you used all the boiling water, and the
ice was just freezing, I think the bath would come to 84 F or 29
c -- pretty tepid. That's 200 pounds of ice and 800 pounds of
boiling water. Anybody check that out? Of course you don't know
how far below freezing the ice cubes were. One assumes sea level
and distilled water.

RE: feedforward in steering a car, and ignore this if I'm
repeating myself.

If you adjust the place on the road where you look, you can
anticipate the curves without feedforward. By looking at the road
just far enough ahead of the car, you will see a deviation in the
road before the car gets to the curve. This distance has to be
adjusted for the speed of the car, so higher-level control is
involved. With just the right distance, reacting to the
disturbance in the usual way will result in the commencement of a
steering effort just when it's needed. Try it: it works. Of
course there's no way to prove that anyone ever did it this way



Bill P.