Comparison of the Quality Criterion for PID and Predictive Controllers

The advent of predictive controllers such as Dynamic Matrix Control (DMC) has created a need to set new criterion for the performance of a controller. Traditionally the PID controller has been viewed as being reasonably well tuned if the system settled out with the amplitude of its cyclic behavior being attenuated by one quarter every full cycle. The ever present concern with the stability of the PID controller led people to focus heavily on the cyclic nature of the controller when developing tuning criteria. The movement of the manipulated variable has not been considered except in the context of stability. When comparing the performance of predictive controllers with PID controllers, it becomes apparent that the movement in the manipulated input should not be neglected for either type of controller.