If you poke a system, does it return to equilibrium or blow up? A stable system settles; an unstable one oscillates wildly or accelerates to destruction. Damping: Think of a door closer. Underdamped: The door swings back and forth before closing. Overdamped: The door takes forever to close.
At its heart, control theory is about making a system (the ) behave the way you want (the Reference ) by using a Controller . Fundamentals of Control Theory: An Intuitive Ap...
Your desired state (e.g., "Set speed to 65 mph"). If you poke a system, does it return
"The Present." The harder you are from the goal, the harder you push. If the error is big, the response is big. Underdamped: The door swings back and forth before closing
You set a timer on a toaster. It toasts for 2 minutes regardless of whether the bread is frozen or already burnt. No feedback.
"The Past." If you’ve been slightly off the goal for a long time, this adds up the "history" of the error and gives an extra nudge to eliminate steady-state offset.