Industrial & Engineering Chemistry Research, Vol.38, No.10, 4113-4119, 1999
Partitioned error control
We propose a new two-degrees-of-freedom control structure. Two-degrees-of-freedom controllers are usually implemented when there are stringent requirements on both setpoint tracking and disturbance rejection. Two-degrees-of-freedom controllers are not new; however, the structure of our controller is novel and has several desirable features. It is also a model-based two-degrees-of-freedom controller, but is not quite the same as an internal model control controller. Under the perfect model assumption, the characteristic equations for the setpoint change and load disturbance are distinct and include the process model and the controller designed to handle each disturbance. This control structure allows for separate controllers to be designed to handle setpoint changes and load disturbances. Another desirable feature is that it allows for simple closed-loop determination of the process model.