Nice article on PID controllers:
And another one:
This is probably for any one who is makeing a robot and needs a clossed loo=
p control ciruit for speed control.
IE instead of telling a speed control or an H bridge you want this much pow=
er, you creat the control and tell it what rpm (ground speed) you want and =
through PID control(Probably just PI from what I understand about motors), =
it matches it on the fly regardless if of voltage (like using two different=
batteries or if batteries are starting to loose current, or other irregula=
Try Live.com - your fast, personalized homepage with all the things you car=
e about in one place.