Depending on the controlled variable and how fast or slow it changes, every control system must have a controller that provides a signal to the final control element. Keep in mind that the controller is the decision maker that sends a signal to a final control element based on two things: the desired set-point and a current situation of a variable to be controlled.

Discuss the four control modes (on-off, proportional, proportional-integral, and proportional-integral-derivative) in terms of advantages, disadvantages, and characteristics providing examples for each scenario.