ABSTRACT
In the water-heater experiment of Chapter 5, we saw the PID controller proposed as a way to correct for a standing error. It is a useful device that industry applies to a variety of problems. With the derivative (or phase advance) action of the “D” term added to the proportional “P” term, many second-order systems can be brought to stability. The integral “I” term means that the drive will continue to increase until the error has been driven to zero-or until the limit of maximum drive is reached.
