PID Control

[efoote868]

In theory, you shouldn't need to cap I... when at rest, I is a constant (because the system will automagically set I itself). I gets bigger, and bigger, and then less and less gradually increase (increasing, concave down). If theres an overshoot, I gets smaller (because its subtracted).

Also, when tuning the PID, start with P, then I, then D. Its very helpful to drastically change the constants, for instance, when we were tuning our arm's PID, we started just incrementing P by just 2s.... when it was divided by 32? anyhow, relatively no change. When we began testing, we didn't notice any change in the robot, sometimes even a change for the worse (giving us a false assumption that what we're doing was bad...)

(back to the original post)

There probably wouldn't be a frightful amount of oscillation, have you ever rode a Segway? If you tuned it to perfection, there would always be oscillation. It would probably be to your advantage, however, to have a nearly balanced robot to begin with, with a very low center of gravity.

If I was building a self balancing robot, I would use a PID loop, and then use some sort of cap for the I... for instance, if the robot is moving at its maximum speed, then I can no longer increase, only decrease, or remain constant.

Hope this helps!