EFFECT OF DISTURBANCES
Much of the differences in approaches to controller algorithms and tuning can be traced back to assumptions made about the type and importance of disturbances. Each method has merits based on the disturbance frequency, location, and time lag. Here we gain an understanding of how to reduce process variability from upsets originating from changes in raw materials, production rates, weather, operating conditions, or other loops. The knowledge provides the guidance on how to track down the origin and eliminate or at least reduce the size or speed of the disturbance.
The emphasis in the control literature is on setpoint response. When the ability to handle disturbances is studied, a ...